{"id":37282,"date":"2025-12-29T14:55:42","date_gmt":"2025-12-29T07:55:42","guid":{"rendered":"https:\/\/interdata.vn\/blog\/?p=37282"},"modified":"2025-12-29T14:55:42","modified_gmt":"2025-12-29T07:55:42","slug":"cache-hit-va-cache-miss-la-gi","status":"publish","type":"post","link":"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/","title":{"rendered":"Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec? T\u1ed5ng quan ki\u1ebfn th\u1ee9c \u0111\u1ea7y \u0111\u1ee7, d\u1ec5 hi\u1ec3u"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">N\u1ed8I DUNG<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cache-la-gi\" >Cache l\u00e0 g\u00ec?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cache-nam-o-dau-trong-he-thong\" >Cache n\u1eb1m \u1edf \u0111\u00e2u trong h\u1ec7 th\u1ed1ng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Vi-sao-cache-giup-tang-toc-do-xu-ly\" >V\u00ec sao cache gi\u00fap t\u0103ng t\u1ed1c \u0111\u1ed9 x\u1eed l\u00fd?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cache-Hit-la-gi\" >Cache Hit l\u00e0 g\u00ec?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Quy-trinh-dien-ra\" >Quy tr\u00ecnh di\u1ec5n ra<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Vi-du-minh-hoa-Analogy\" >V\u00ed d\u1ee5 minh h\u1ecda (Analogy)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cache-Miss-la-gi\" >Cache Miss l\u00e0 g\u00ec?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Quy-trinh-dien-ra-2\" >Quy tr\u00ecnh di\u1ec5n ra<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Nguyen-nhan-pho-bien-dan-den-Cache-Miss\" >Nguy\u00ean nh\u00e2n ph\u1ed5 bi\u1ebfn d\u1eabn \u0111\u1ebfn Cache Miss<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Vi-du-minh-hoa\" >V\u00ed d\u1ee5 minh h\u1ecda<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Phan-biet-Cache-Hit-va-Cache-Miss\" >Ph\u00e2n bi\u1ec7t Cache Hit v\u00e0 Cache Miss<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Phan-loai-cac-dang-Cache-Miss-Mo-hinh-3C\" >Ph\u00e2n lo\u1ea1i c\u00e1c d\u1ea1ng Cache Miss (M\u00f4 h\u00ecnh 3C)<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#1-Compulsory-Miss-Miss-bat-buoc-Cold-Miss\" >1. Compulsory Miss (Miss b\u1eaft bu\u1ed9c \/ Cold Miss)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#2-Capacity-Miss-Miss-do-dung-luong\" >2. Capacity Miss (Miss do dung l\u01b0\u1ee3ng)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#3-Conflict-Miss-Miss-do-xung-dot\" >3. Conflict Miss (Miss do xung \u0111\u1ed9t)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cach-tinh-Cache-Hit-Cache-Hit-Ratio\" >C\u00e1ch t\u00ednh Cache Hit (Cache Hit Ratio)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cach-tinh-Cache-Miss-Cache-Miss-Ratio\" >C\u00e1ch t\u00ednh Cache Miss (Cache Miss Ratio)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Tong-quan-ve-y-nghia-Cache-Hit-va-Cache-Miss\" >T\u1ed5ng quan v\u1ec1 \u00fd ngh\u0129a Cache Hit v\u00e0 Cache Miss<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-19\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Ti-le-Cache-Hit-va-Cache-Miss-ly-tuong-va-toc-do-tai-trang\" >T\u1ec9 l\u1ec7 Cache Hit v\u00e0 Cache Miss l\u00fd t\u01b0\u1edfng v\u00e0 t\u1ed1c \u0111\u1ed9 t\u1ea3i trang<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-20\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Vi-sao-ti-le-Cache-Hit-va-Cache-Miss-ly-tuong-lai-quan-trong\" >V\u00ec sao t\u1ec9 l\u1ec7 Cache Hit v\u00e0 Cache Miss l\u00fd t\u01b0\u1edfng l\u1ea1i quan tr\u1ecdng?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-21\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Anh-huong-cua-Cache-Hit-va-Cache-Miss-den-toc-do-tai-trang\" >\u1ea2nh h\u01b0\u1edfng c\u1ee7a Cache Hit v\u00e0 Cache Miss \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 t\u1ea3i trang<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-22\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Khi-nao-Cache-Hit-cao-nhung-he-thong-van-cham\" >Khi n\u00e0o Cache Hit cao nh\u01b0ng h\u1ec7 th\u1ed1ng v\u1eabn ch\u1eadm?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-23\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#1-Cache-Layer-dat-sai-vi-tri-hoac-do-tre-mang-Network-Latency\" >1. Cache Layer \u0111\u1eb7t sai v\u1ecb tr\u00ed ho\u1eb7c \u0111\u1ed9 tr\u1ec5 m\u1ea1ng (Network Latency)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-24\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#2-Van-de-tuan-tu-hoa-du-lieu-Serialization-Overhead\" >2. V\u1ea5n \u0111\u1ec1 tu\u1ea7n t\u1ef1 h\u00f3a d\u1eef li\u1ec7u (Serialization Overhead)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-25\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#3-Cache-Stampede-Hieu-ung-dam-dong\" >3. Cache Stampede (Hi\u1ec7u \u1ee9ng \u0111\u00e1m \u0111\u00f4ng)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-26\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cach-cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao\" >C\u00e1ch c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t cache khi t\u1ec9 l\u1ec7 Cache Miss cao<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-27\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#1-Tang-dung-luong-bo-nho-cache\" >1. T\u0103ng dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb cache<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-28\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#2-Ap-dung-cache-dong-Dynamic-Caching\" >2. \u00c1p d\u1ee5ng cache \u0111\u1ed9ng (Dynamic Caching)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-29\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#3-Dieu-chinh-va-toi-uu-cau-hinh-cache\" >3. \u0110i\u1ec1u ch\u1ec9nh v\u00e0 t\u1ed1i \u01b0u c\u1ea5u h\u00ecnh cache<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-30\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#4-Toi-uu-hoa-he-thong-Content-Delivery-Network-CDN\" >4. T\u1ed1i \u01b0u h\u00f3a h\u1ec7 th\u1ed1ng Content Delivery Network (CDN)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-31\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#5-Ra-soat-va-khac-phuc-loi-trong-cau-hinh-cache\" >5. R\u00e0 so\u00e1t v\u00e0 kh\u1eafc ph\u1ee5c l\u1ed7i trong c\u1ea5u h\u00ecnh cache<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-32\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#6-Chon-cong-cu-cache-phu-hop-voi-he-thong\" >6. Ch\u1ecdn c\u00f4ng c\u1ee5 cache ph\u00f9 h\u1ee3p v\u1edbi h\u1ec7 th\u1ed1ng<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-33\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#7-Toi-uu-ma-nguon-va-cau-truc-website\" >7. T\u1ed1i \u01b0u m\u00e3 ngu\u1ed3n v\u00e0 c\u1ea5u tr\u00fac website<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-34\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#8-Ap-dung-cac-ky-thuat-cache-nang-cao\" >8. \u00c1p d\u1ee5ng c\u00e1c k\u1ef9 thu\u1eadt cache n\u00e2ng cao<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-35\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Cac-van-de-thuong-gap-khi-trien-khai-Cache-trong-he-thong\" >C\u00e1c v\u1ea5n \u0111\u1ec1 th\u01b0\u1eddng g\u1eb7p khi tri\u1ec3n khai Cache trong h\u1ec7 th\u1ed1ng<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-36\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Bai-toan-dong-bo-du-lieu-Cache-Invalidation\" >B\u00e0i to\u00e1n \u0111\u1ed3ng b\u1ed9 d\u1eef li\u1ec7u (Cache Invalidation)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-37\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Gioi-han-dung-luong-bo-nho-cache\" >Gi\u1edbi h\u1ea1n dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb cache<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-38\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Chi-phi-quan-ly-va-bao-tri-he-thong-cache\" >Chi ph\u00ed qu\u1ea3n l\u00fd v\u00e0 b\u1ea3o tr\u00ec h\u1ec7 th\u1ed1ng cache<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-39\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Mot-so-thuat-toan-thay-the-Cache-pho-bien-Cache-Replacement-Policies\" >M\u1ed9t s\u1ed1 thu\u1eadt to\u00e1n thay th\u1ebf Cache ph\u1ed5 bi\u1ebfn (Cache Replacement Policies)<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-40\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#1-LRU-Least-Recently-Used-%E2%80%93-It-duoc-su-dung-gan-day-nhat\" >1. LRU (Least Recently Used) &#8211; \u00cdt \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng g\u1ea7n \u0111\u00e2y nh\u1ea5t<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-41\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#2-FIFO-First-In-First-Out-%E2%80%93-Vao-truoc-ra-truoc\" >2. FIFO (First In First Out) &#8211; V\u00e0o tr\u01b0\u1edbc ra tr\u01b0\u1edbc<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-42\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#3-LFU-Least-Frequently-Used-%E2%80%93-It-duoc-su-dung-thuong-xuyen-nhat\" >3. LFU (Least Frequently Used) &#8211; \u00cdt \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng th\u01b0\u1eddng xuy\u00ean nh\u1ea5t<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-43\" href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/#Ket-luan\" >K\u1ebft lu\u1eadn<\/a><\/li><\/ul><\/nav><\/div>\n<p>Khi website ho\u1eb7c h\u1ec7 th\u1ed1ng x\u1eed l\u00fd d\u1eef li\u1ec7u ng\u00e0y c\u00e0ng l\u1edbn, t\u1ed1c \u0111\u1ed9 ph\u1ea3n h\u1ed3i tr\u1edf th\u00e0nh y\u1ebfu t\u1ed1 then ch\u1ed1t \u1ea3nh h\u01b0\u1edfng tr\u1ef1c ti\u1ebfp \u0111\u1ebfn <a href=\"https:\/\/interdata.vn\/blog\/ux-la-gi\/\">tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng<\/a> v\u00e0 hi\u1ec7u su\u1ea5t v\u1eadn h\u00e0nh. M\u1ed9t trong nh\u1eefng k\u1ef9 thu\u1eadt quan tr\u1ecdng gi\u00fap t\u0103ng t\u1ed1c h\u1ec7 th\u1ed1ng ch\u00ednh l\u00e0 cache. Tuy nhi\u00ean, vi\u1ec7c cache c\u00f3 th\u1ef1c s\u1ef1 ph\u00e1t huy hi\u1ec7u qu\u1ea3 hay kh\u00f4ng l\u1ea1i ph\u1ee5 thu\u1ed9c nhi\u1ec1u v\u00e0o hai kh\u00e1i ni\u1ec7m c\u1ed1t l\u00f5i: Cache Hit v\u00e0 Cache Miss.<\/p>\n<p>Trong b\u00e0i vi\u1ebft n\u00e0y, ch\u00fang ta s\u1ebd c\u00f9ng t\u00ecm hi\u1ec3u <a href=\"https:\/\/interdata.vn\/blog\/cache-hit-va-cache-miss-la-gi\/\"><strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong><\/a>, c\u00e1ch ch\u00fang \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 t\u1ea3i trang, hi\u1ec7u n\u0103ng h\u1ec7 th\u1ed1ng v\u00e0 v\u00ec sao vi\u1ec7c t\u1ed1i \u01b0u t\u1ec9 l\u1ec7 hit\/miss l\u1ea1i \u0111\u00f3ng vai tr\u00f2 quan tr\u1ecdng trong c\u00e1c h\u1ec7 th\u1ed1ng web hi\u1ec7n \u0111\u1ea1i.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cache-la-gi\"><\/span>Cache l\u00e0 g\u00ec?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><strong>Cache<\/strong> (b\u1ed9 nh\u1edb \u0111\u1ec7m) l\u00e0 m\u1ed9t v\u00f9ng l\u01b0u tr\u1eef d\u1eef li\u1ec7u t\u1ea1m th\u1eddi, Cache th\u01b0\u1eddng c\u00f3 t\u1ed1c \u0111\u1ed9 truy xu\u1ea5t nhanh h\u01a1n b\u1ed9 nh\u1edb c\u1ea5p th\u1ea5p, gi\u00fap <a href=\"https:\/\/interdata.vn\/blog\/cpu-server\/\">CPU<\/a> ho\u1eb7c c\u00e1c \u1ee9ng d\u1ee5ng l\u1ea5y \u0111\u01b0\u1ee3c d\u1eef li\u1ec7u c\u1ea7n thi\u1ebft m\u00e0 kh\u00f4ng ph\u1ea3i t\u1ed1n c\u00f4ng t\u00ecm ki\u1ebfm \u1edf n\u01a1i l\u01b0u tr\u1eef g\u1ed1c (v\u1ed1n c\u00f3 t\u1ed1c \u0111\u1ed9 ch\u1eadm h\u01a1n).<\/p>\n<p>Nhi\u1ec1u b\u1ea1n sinh vi\u00ean IT hay c\u00e1c Junior Developer th\u01b0\u1eddng b\u1ecf qua b\u01b0\u1edbc n\u00e0y v\u00e0 nh\u1ea3y ngay v\u00e0o code, d\u1eabn \u0111\u1ebfn vi\u1ec7c t\u01b0 duy h\u1ec7 th\u1ed1ng b\u1ecb h\u1ed5ng.<\/p>\n<figure id=\"attachment_37283\" aria-describedby=\"caption-attachment-37283\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37283\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-la-gi.jpg\" alt=\"Cache l\u00e0 g\u00ec\" width=\"800\" height=\"500\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-la-gi.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-la-gi-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-la-gi-768x480.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-37283\" class=\"wp-caption-text\">Cache l\u00e0 g\u00ec?<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"Cache-nam-o-dau-trong-he-thong\"><\/span>Cache n\u1eb1m \u1edf \u0111\u00e2u trong h\u1ec7 th\u1ed1ng?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Trong ki\u1ebfn tr\u00fac m\u00e1y t\u00ednh v\u00e0 thi\u1ebft k\u1ebf h\u1ec7 th\u1ed1ng hi\u1ec7n \u0111\u1ea1i, Cache kh\u00f4ng ch\u1ec9 n\u1eb1m \u1edf m\u1ed9t ch\u1ed7. Ch\u00fang hi\u1ec7n di\u1ec7n \u1edf kh\u1eafp m\u1ecdi n\u01a1i, t\u1ea1o th\u00e0nh c\u00e1c l\u1edbp (layers) \u0111\u1ec3 h\u1ed7 tr\u1ee3 l\u1eabn nhau:<\/p>\n<ul>\n<li><strong>Hardware Cache (CPU Cache):<\/strong> \u0110\u00e2y l\u00e0 lo\u1ea1i cache nhanh nh\u1ea5t v\u00e0 \u0111\u1eaft \u0111\u1ecf nh\u1ea5t. Ch\u00fang n\u1eb1m ngay trong ho\u1eb7c r\u1ea5t g\u1ea7n CPU (L1, L2, L3 Cache). Nhi\u1ec7m v\u1ee5 c\u1ee7a ch\u00fang l\u00e0 l\u01b0u tr\u1eef c\u00e1c l\u1ec7nh v\u00e0 d\u1eef li\u1ec7u m\u00e0 CPU th\u01b0\u1eddng xuy\u00ean s\u1eed d\u1ee5ng \u0111\u1ec3 gi\u1ea3m thi\u1ec3u th\u1eddi gian ch\u1edd \u0111\u1ee3i t\u1eeb <a href=\"https:\/\/interdata.vn\/blog\/ram-server\/\">RAM<\/a>.<\/li>\n<li><strong>Browser Cache:<\/strong> Khi b\u1ea1n l\u01b0\u1edbt web, tr\u00ecnh duy\u1ec7t (Chrome, Firefox) s\u1ebd l\u01b0u l\u1ea1i c\u00e1c file t\u0129nh nh\u01b0 h\u00ecnh \u1ea3nh, CSS, JavaScript v\u00e0o \u1ed5 c\u1ee9ng m\u00e1y t\u00ednh. L\u1ea7n sau b\u1ea1n v\u00e0o l\u1ea1i trang web \u0111\u00f3, tr\u00ecnh duy\u1ec7t s\u1ebd t\u1ea3i t\u1eeb \u1ed5 c\u1ee9ng thay v\u00ec t\u1ea3i l\u1ea1i t\u1eeb server.<\/li>\n<li><strong>CDN (<a href=\"https:\/\/interdata.vn\/blog\/cdn-la-gi\/\">Content Delivery Network<\/a>):<\/strong> \u0110\u00e2y l\u00e0 h\u1ec7 th\u1ed1ng cache ph\u00e2n t\u00e1n tr\u00ean to\u00e0n c\u1ea7u. V\u00ed d\u1ee5 server g\u1ed1c c\u1ee7a b\u1ea1n \u1edf Vi\u1ec7t Nam, nh\u01b0ng ng\u01b0\u1eddi d\u00f9ng \u1edf M\u1ef9 truy c\u1eadp v\u00e0o. CDN s\u1ebd cache n\u1ed9i dung t\u1ea1i server \u1edf M\u1ef9 \u0111\u1ec3 ng\u01b0\u1eddi d\u00f9ng t\u1ea3i nhanh h\u01a1n.<\/li>\n<li><strong>Application\/Database Cache:<\/strong> C\u00e1c c\u00f4ng ngh\u1ec7 nh\u01b0 Redis hay Memcached th\u01b0\u1eddng \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 l\u01b0u k\u1ebft qu\u1ea3 c\u1ee7a c\u00e1c c\u00e2u truy v\u1ea5n database ph\u1ee9c t\u1ea1p. Thay v\u00ec m\u1ed7i l\u1ea7n f5 trang web l\u00e0 m\u1ed9t l\u1ea7n query database, \u1ee9ng d\u1ee5ng s\u1ebd l\u1ea5y k\u1ebft qu\u1ea3 t\u1eeb Redis.<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Vi-sao-cache-giup-tang-toc-do-xu-ly\"><\/span>V\u00ec sao cache gi\u00fap t\u0103ng t\u1ed1c \u0111\u1ed9 x\u1eed l\u00fd?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Nguy\u00ean l\u00fd c\u01a1 b\u1ea3n c\u1ee7a cache d\u1ef1a tr\u00ean s\u1ef1 ch\u00eanh l\u1ec7ch v\u1ec1 t\u1ed1c \u0111\u1ed9 gi\u1eefa c\u00e1c lo\u1ea1i b\u1ed9 nh\u1edb.<\/p>\n<p>B\u1ea1n h\u00e3y t\u01b0\u1edfng t\u01b0\u1ee3ng CPU l\u00e0 m\u1ed9t \u0111\u1ea7u b\u1ebfp si\u00eau h\u1ea1ng, c\u00f3 th\u1ec3 th\u00e1i rau trong 1 gi\u00e2y. Nh\u01b0ng t\u1ee7 l\u1ea1nh (\u1ed5 c\u1ee9ng HDD\/SSD) l\u1ea1i n\u1eb1m \u1edf t\u1ea7ng d\u01b0\u1edbi. M\u1ed7i l\u1ea7n c\u1ea7n l\u1ea5y m\u1ed9t qu\u1ea3 tr\u1ee9ng, \u0111\u1ea7u b\u1ebfp ph\u1ea3i ch\u1ea1y xu\u1ed1ng t\u1ea7ng, m\u1ea5t 10 ph\u00fat. D\u00f9 \u0111\u1ea7u b\u1ebfp c\u00f3 gi\u1ecfi \u0111\u1ebfn \u0111\u00e2u, th\u1eddi gian n\u1ea5u \u0103n v\u1eabn s\u1ebd r\u1ea5t l\u00e2u do th\u1eddi gian di chuy\u1ec3n.<\/p>\n<p>Cache ch\u00ednh l\u00e0 m\u1ed9t chi\u1ebfc b\u00e0n nh\u1ecf \u0111\u1eb7t ngay c\u1ea1nh b\u1ebfp. \u0110\u1ea7u b\u1ebfp s\u1ebd \u0111\u1ec3 nh\u1eefng nguy\u00ean li\u1ec7u hay d\u00f9ng nh\u1ea5t (mu\u1ed1i, ti\u00eau, h\u00e0nh) ngay tr\u00ean b\u00e0n. Khi c\u1ea7n, \u00f4ng ch\u1ec9 m\u1ea5t 0.1 gi\u00e2y \u0111\u1ec3 v\u1edbi tay l\u1ea5y. H\u1ec7 th\u1ed1ng m\u00e1y t\u00ednh c\u0169ng ho\u1ea1t \u0111\u1ed9ng y nh\u01b0 v\u1eady. Cache gi\u00fap thu h\u1eb9p kho\u1ea3ng c\u00e1ch gi\u1eefa b\u1ed9 x\u1eed l\u00fd t\u1ed1c \u0111\u1ed9 cao v\u00e0 n\u01a1i l\u01b0u tr\u1eef d\u1eef li\u1ec7u t\u1ed1c \u0111\u1ed9 th\u1ea5p.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cache-Hit-la-gi\"><\/span>Cache Hit l\u00e0 g\u00ec?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><strong>Cache Hit<\/strong> x\u1ea3y ra khi h\u1ec7 th\u1ed1ng (CPU, tr\u00ecnh duy\u1ec7t, ho\u1eb7c \u1ee9ng d\u1ee5ng) g\u1eedi y\u00eau c\u1ea7u truy xu\u1ea5t m\u1ed9t d\u1eef li\u1ec7u c\u1ee5 th\u1ec3 v\u00e0 t\u00ecm th\u1ea5y d\u1eef li\u1ec7u \u0111\u00f3 ngay trong b\u1ed9 nh\u1edb Cache. L\u00fac n\u00e0y, d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c tr\u1ea3 v\u1ec1 ngay l\u1eadp t\u1ee9c m\u00e0 kh\u00f4ng c\u1ea7n truy v\u1ea5n xu\u1ed1ng b\u1ed9 nh\u1edb c\u1ea5p th\u1ea5p h\u01a1n (nh\u01b0 RAM hay \u1ed4 c\u1ee9ng).<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Quy-trinh-dien-ra\"><\/span>Quy tr\u00ecnh di\u1ec5n ra<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u1ed9t chu tr\u00ecnh Cache Hit \u0111i\u1ec3n h\u00ecnh di\u1ec5n ra theo c\u00e1c b\u01b0\u1edbc sau:<\/p>\n<ol>\n<li><strong>Y\u00eau c\u1ea7u:<\/strong> CPU (ho\u1eb7c Client) g\u1eedi t\u00edn hi\u1ec7u c\u1ea7n \u0111\u1ecdc d\u1eef li\u1ec7u t\u1ea1i \u0111\u1ecba ch\u1ec9 X.<\/li>\n<li><strong>Ki\u1ec3m tra (Lookup):<\/strong> B\u1ed9 \u0111i\u1ec1u khi\u1ec3n Cache (Cache Controller) qu\u00e9t nhanh trong b\u1ea3ng ch\u1ec9 m\u1ee5c c\u1ee7a Cache \u0111\u1ec3 xem \u0111\u1ecba ch\u1ec9 X c\u00f3 \u0111ang \u0111\u01b0\u1ee3c l\u01b0u hay kh\u00f4ng.<\/li>\n<li><strong>X\u00e1c nh\u1eadn (Hit):<\/strong> H\u1ec7 th\u1ed1ng x\u00e1c nh\u1eadn &#8220;C\u00f3 d\u1eef li\u1ec7u X \u1edf \u0111\u00e2y&#8221;.<\/li>\n<li><strong>Ph\u1ea3n h\u1ed3i:<\/strong> D\u1eef li\u1ec7u t\u1eeb Cache \u0111\u01b0\u1ee3c truy\u1ec1n tr\u1ef1c ti\u1ebfp cho CPU.<\/li>\n<\/ol>\n<p>Quy tr\u00ecnh n\u00e0y di\u1ec5n ra c\u1ef1c k\u1ef3 nhanh, th\u01b0\u1eddng ch\u1ec9 m\u1ea5t v\u00e0i nano gi\u00e2y (ns) \u0111\u1ed1i v\u1edbi CPU Cache.<\/p>\n<figure id=\"attachment_37284\" aria-describedby=\"caption-attachment-37284\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37284\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Hit-la-gi.jpg\" alt=\"Cache Hit l\u00e0 g\u00ec\" width=\"800\" height=\"500\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Hit-la-gi.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Hit-la-gi-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Hit-la-gi-768x480.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-37284\" class=\"wp-caption-text\">Cache Hit l\u00e0 g\u00ec?<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"Vi-du-minh-hoa-Analogy\"><\/span>V\u00ed d\u1ee5 minh h\u1ecda (Analogy)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>H\u00e3y quay l\u1ea1i v\u00ed d\u1ee5 v\u1ec1 ng\u01b0\u1eddi \u0111\u1ea7u b\u1ebfp.<\/p>\n<p>\u0110\u1ea7u b\u1ebfp c\u1ea7n &#8220;mu\u1ed1i&#8221; \u0111\u1ec3 n\u00eam canh. \u00d4ng nh\u00ecn ngay v\u00e0o chi\u1ebfc b\u00e0n nh\u1ecf b\u00ean c\u1ea1nh (Cache) v\u00e0 th\u1ea5y l\u1ecd mu\u1ed1i \u0111ang n\u1eb1m \u0111\u00f3. \u00d4ng c\u1ea7m l\u1ea5y v\u00e0 n\u00eam ngay. Qu\u00e1 tr\u00ecnh n\u00e0y di\u1ec5n ra t\u1ee9c th\u00ec, kh\u00f4ng l\u00e0m gi\u00e1n \u0111o\u1ea1n vi\u1ec7c n\u1ea5u n\u01b0\u1edbng. \u0110\u00e2y ch\u00ednh l\u00e0 m\u1ed9t pha <strong>Cache Hit<\/strong>.<\/p>\n<p>Trong th\u1ef1c t\u1ebf l\u1eadp tr\u00ecnh web:<\/p>\n<p>M\u1ed9t ng\u01b0\u1eddi d\u00f9ng truy c\u1eadp v\u00e0o b\u00e0i vi\u1ebft A tr\u00ean website c\u1ee7a b\u1ea1n. H\u1ec7 th\u1ed1ng ki\u1ec3m tra Redis v\u00e0 th\u1ea5y n\u1ed9i dung b\u00e0i vi\u1ebft A \u0111\u00e3 \u0111\u01b0\u1ee3c l\u01b0u s\u1eb5n. Website hi\u1ec3n th\u1ecb n\u1ed9i dung cho ng\u01b0\u1eddi d\u00f9ng ch\u1ec9 trong 50ms. \u0110\u00f3 l\u00e0 Cache Hit. Hi\u1ec3u r\u00f5 k\u1ecbch b\u1ea3n n\u00e0y l\u00e0 b\u01b0\u1edbc \u0111\u1ea7u ti\u00ean \u0111\u1ec3 n\u1eafm b\u1eaft <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong>.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cache-Miss-la-gi\"><\/span>Cache Miss l\u00e0 g\u00ec?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><strong>Cache Miss<\/strong> x\u1ea3y ra khi h\u1ec7 th\u1ed1ng t\u00ecm ki\u1ebfm d\u1eef li\u1ec7u trong b\u1ed9 nh\u1edb Cache nh\u01b0ng kh\u00f4ng th\u1ea5y. Khi \u0111\u00f3, h\u1ec7 th\u1ed1ng b\u1eaft bu\u1ed9c ph\u1ea3i t\u00ecm ki\u1ebfm d\u1eef li\u1ec7u \u1edf b\u1ed9 nh\u1edb ch\u00ednh (RAM) ho\u1eb7c b\u1ed9 nh\u1edb l\u01b0u tr\u1eef (HDD\/SSD). Sau khi t\u00ecm th\u1ea5y, d\u1eef li\u1ec7u n\u00e0y th\u01b0\u1eddng s\u1ebd \u0111\u01b0\u1ee3c sao ch\u00e9p v\u00e0o Cache \u0111\u1ec3 ph\u1ee5c v\u1ee5 cho c\u00e1c l\u1ea7n truy c\u1eadp sau.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Quy-trinh-dien-ra-2\"><\/span>Quy tr\u00ecnh di\u1ec5n ra<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Quy tr\u00ecnh c\u1ee7a m\u1ed9t pha Cache Miss ph\u1ee9c t\u1ea1p v\u00e0 t\u1ed1n th\u1eddi gian h\u01a1n nhi\u1ec1u:<\/p>\n<ol>\n<li><strong>Y\u00eau c\u1ea7u:<\/strong> CPU g\u1eedi y\u00eau c\u1ea7u \u0111\u1ecdc d\u1eef li\u1ec7u t\u1ea1i \u0111\u1ecba ch\u1ec9 Y.<\/li>\n<li><strong>Ki\u1ec3m tra (Lookup):<\/strong> B\u1ed9 \u0111i\u1ec1u khi\u1ec3n Cache qu\u00e9t v\u00e0 tr\u1ea3 v\u1ec1 k\u1ebft qu\u1ea3 &#8220;Kh\u00f4ng t\u00ecm th\u1ea5y&#8221;.<\/li>\n<li><strong>Truy xu\u1ea5t (Fetch):<\/strong> Y\u00eau c\u1ea7u \u0111\u01b0\u1ee3c chuy\u1ec3n ti\u1ebfp xu\u1ed1ng b\u1ed9 nh\u1edb c\u1ea5p th\u1ea5p h\u01a1n (RAM).<\/li>\n<li><strong>Sao ch\u00e9p (Allocate):<\/strong> D\u1eef li\u1ec7u Y \u0111\u01b0\u1ee3c t\u00ecm th\u1ea5y \u1edf RAM, sau \u0111\u00f3 \u0111\u01b0\u1ee3c g\u1eedi cho CPU, \u0111\u1ed3ng th\u1eddi m\u1ed9t b\u1ea3n sao c\u1ee7a Y \u0111\u01b0\u1ee3c ghi v\u00e0o Cache.<\/li>\n<li><strong>Ho\u00e0n t\u1ea5t:<\/strong> CPU nh\u1eadn d\u1eef li\u1ec7u v\u00e0 ti\u1ebfp t\u1ee5c x\u1eed l\u00fd.<\/li>\n<\/ol>\n<p>T\u1ea1i \u0111\u00e2y xu\u1ea5t hi\u1ec7n kh\u00e1i ni\u1ec7m <strong>Cache Penalty<\/strong> (ho\u1eb7c Miss Penalty). \u0110\u00e2y l\u00e0 kho\u1ea3ng th\u1eddi gian b\u1ecb tr\u1ec5 th\u00eam do h\u1ec7 th\u1ed1ng ph\u1ea3i &#8220;\u0111i \u0111\u01b0\u1eddng v\u00f2ng&#8221; xu\u1ed1ng b\u1ed9 nh\u1edb th\u1ea5p h\u01a1n \u0111\u1ec3 l\u1ea5y d\u1eef li\u1ec7u, c\u1ed9ng v\u1edbi th\u1eddi gian ghi d\u1eef li\u1ec7u \u0111\u00f3 v\u00e0o Cache.<\/p>\n<figure id=\"attachment_37285\" aria-describedby=\"caption-attachment-37285\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37285\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Miss-la-gi.png\" alt=\"Cache Miss l\u00e0 g\u00ec\" width=\"800\" height=\"383\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Miss-la-gi.png 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Miss-la-gi-300x144.png 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cache-Miss-la-gi-768x368.png 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-37285\" class=\"wp-caption-text\">Cache Miss l\u00e0 g\u00ec?<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"Nguyen-nhan-pho-bien-dan-den-Cache-Miss\"><\/span>Nguy\u00ean nh\u00e2n ph\u1ed5 bi\u1ebfn d\u1eabn \u0111\u1ebfn Cache Miss<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Cache Miss c\u00f3 th\u1ec3 x\u1ea3y ra v\u00ec nhi\u1ec1u l\u00fd do kh\u00e1c nhau, trong \u0111\u00f3 th\u01b0\u1eddng g\u1eb7p nh\u1ea5t g\u1ed3m:<\/p>\n<ul>\n<li><strong>D\u1eef li\u1ec7u ch\u01b0a t\u1eebng t\u1ed3n t\u1ea1i trong cache<\/strong>: Tr\u01b0\u1eddng h\u1ee3p n\u00e0y xu\u1ea5t hi\u1ec7n khi m\u1ed9t y\u00eau c\u1ea7u \u0111\u01b0\u1ee3c g\u1eedi \u0111i l\u1ea7n \u0111\u1ea7u ti\u00ean, khi\u1ebfn h\u1ec7 th\u1ed1ng ch\u01b0a c\u00f3 s\u1eb5n d\u1eef li\u1ec7u \u0111\u1ec3 ph\u1ee5c v\u1ee5 t\u1eeb cache.<\/li>\n<li><strong>D\u1eef li\u1ec7u b\u1ecb lo\u1ea1i b\u1ecf ho\u1eb7c b\u1ecb ghi \u0111\u00e8<\/strong>: Khi dung l\u01b0\u1ee3ng cache \u0111\u1ea1t gi\u1edbi h\u1ea1n, h\u1ec7 th\u1ed1ng s\u1ebd x\u00f3a c\u00e1c d\u1eef li\u1ec7u c\u0169 \u0111\u1ec3 d\u00e0nh ch\u1ed7 cho d\u1eef li\u1ec7u m\u1edbi, d\u1eabn \u0111\u1ebfn cache Miss n\u1ebfu d\u1eef li\u1ec7u c\u1ea7n truy xu\u1ea5t \u0111\u00e3 b\u1ecb lo\u1ea1i b\u1ecf.<\/li>\n<li><strong>D\u1eef li\u1ec7u trong cache \u0111\u00e3 h\u1ebft h\u1ea1n<\/strong>: M\u1ed7i b\u1ea3n ghi cache \u0111\u1ec1u c\u00f3 th\u1eddi gian s\u1ed1ng (TTL) nh\u1ea5t \u0111\u1ecbnh. Khi th\u1eddi gian n\u00e0y k\u1ebft th\u00fac, cache s\u1ebd b\u1ecb v\u00f4 hi\u1ec7u v\u00e0 h\u1ec7 th\u1ed1ng bu\u1ed9c ph\u1ea3i t\u1ea3i l\u1ea1i d\u1eef li\u1ec7u t\u1eeb ngu\u1ed3n g\u1ed1c.<\/li>\n<li><strong>C\u1ea5u tr\u00fac ho\u1eb7c phi\u00ean b\u1ea3n d\u1eef li\u1ec7u thay \u0111\u1ed5i<\/strong>: Khi d\u1eef li\u1ec7u ngu\u1ed3n \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt ho\u1eb7c thay \u0111\u1ed5i c\u1ea5u tr\u00fac, c\u00e1c b\u1ea3n cache c\u0169 kh\u00f4ng c\u00f2n ch\u00ednh x\u00e1c v\u00e0 s\u1ebd b\u1ecb x\u00f3a \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o d\u1eef li\u1ec7u tr\u1ea3 v\u1ec1 lu\u00f4n \u0111\u00fang.<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"Vi-du-minh-hoa\"><\/span>V\u00ed d\u1ee5 minh h\u1ecda<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>V\u1eabn l\u00e0 ng\u01b0\u1eddi \u0111\u1ea7u b\u1ebfp n\u1ecd. L\u1ea7n n\u00e0y \u00f4ng c\u1ea7n &#8220;Saffron&#8221; (nh\u1ee5y hoa ngh\u1ec7 t\u00e2y) \u0111\u1ec3 n\u1ea5u m\u00f3n \u0111\u1eb7c bi\u1ec7t. \u00d4ng t\u00ecm tr\u00ean b\u00e0n nh\u1ecf (Cache) nh\u01b0ng kh\u00f4ng th\u1ea5y. \u00d4ng bu\u1ed9c ph\u1ea3i ng\u1eebng n\u1ea5u, \u0111i thang b\u1ed9 xu\u1ed1ng t\u1ea7ng h\u1ea7m, m\u1edf t\u1ee7 l\u1ea1nh (RAM\/Disk) \u0111\u1ec3 t\u00ecm h\u1ed9p Saffron. Sau \u0111\u00f3 \u00f4ng mang h\u1ed9p Saffron l\u00ean, l\u1ea5y m\u1ed9t \u00edt \u0111\u1ec3 d\u00f9ng, v\u00e0 ti\u1ec7n tay \u0111\u1ec3 h\u1ed9p Saffron l\u00ean b\u00e0n nh\u1ecf (Cache) v\u00ec ngh\u0129 r\u1eb1ng l\u00e1t n\u1eefa c\u00f3 th\u1ec3 d\u00f9ng l\u1ea1i.<\/p>\n<p>Qu\u1ea3ng th\u1eddi gian \u00f4ng \u0111i xu\u1ed1ng v\u00e0 \u0111i l\u00ean ch\u00ednh l\u00e0 \u0111\u1ed9 tr\u1ec5 (Latency). \u0110\u00e2y l\u00e0 v\u00ed d\u1ee5 \u0111i\u1ec3n h\u00ecnh gi\u00fap b\u1ea1n h\u00ecnh dung <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong> trong \u0111\u1eddi s\u1ed1ng.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Phan-biet-Cache-Hit-va-Cache-Miss\"><\/span>Ph\u00e2n bi\u1ec7t Cache Hit v\u00e0 Cache Miss<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u0110\u1ec3 gi\u00fap b\u1ea1n c\u00f3 c\u00e1i nh\u00ecn t\u1ed5ng quan v\u00e0 d\u1ec5 so s\u00e1nh khi t\u00ecm hi\u1ec3u <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong>, InterData \u0111\u00e3 t\u1ed5ng h\u1ee3p b\u1ea3ng d\u01b0\u1edbi \u0111\u00e2y. Vi\u1ec7c ph\u00e2n bi\u1ec7t r\u00f5 r\u00e0ng hai tr\u1ea1ng th\u00e1i n\u00e0y gi\u00fap b\u1ea1n \u0111\u01b0a ra c\u00e1c quy\u1ebft \u0111\u1ecbnh t\u1ed1i \u01b0u h\u1ec7 th\u1ed1ng ch\u00ednh x\u00e1c h\u01a1n.<\/p>\n<table style=\"width: 100%; border-collapse: collapse; font-family: Arial, sans-serif; font-size: 14px; line-height: 1.6; border-radius: 12px; overflow: hidden;\">\n<thead>\n<tr>\n<th style=\"padding: 14px; color: #ffffff; background: linear-gradient(135deg, #0c40f4, #077ffa, #0497fc); text-align: center;\">Ti\u00eau ch\u00ed<\/th>\n<th style=\"padding: 14px; color: #ffffff; background: linear-gradient(135deg, #0c40f4, #077ffa, #0497fc); text-align: center;\">Cache Hit<\/th>\n<th style=\"padding: 14px; color: #ffffff; background: linear-gradient(135deg, #0c40f4, #077ffa, #0497fc); text-align: center;\">Cache Miss<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"background: #f9fbff;\">\n<td style=\"padding: 12px; font-weight: bold;\">Tr\u1ea1ng th\u00e1i d\u1eef li\u1ec7u<\/td>\n<td style=\"padding: 12px;\">D\u1eef li\u1ec7u <strong>\u0110\u00c3 C\u00d3<\/strong> s\u1eb5n trong b\u1ed9 nh\u1edb \u0111\u1ec7m (Cache).<\/td>\n<td style=\"padding: 12px;\">D\u1eef li\u1ec7u <strong>KH\u00d4NG C\u00d3<\/strong> trong Cache.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding: 12px; font-weight: bold;\">Ngu\u1ed3n l\u1ea5y d\u1eef li\u1ec7u<\/td>\n<td style=\"padding: 12px;\">L\u1ea5y tr\u1ef1c ti\u1ebfp t\u1eeb Cache (L1\/L2\/L3, Redis, CDN&#8230;).<\/td>\n<td style=\"padding: 12px;\">Ph\u1ea3i l\u1ea5y t\u1eeb b\u1ed9 nh\u1edb ch\u00ednh (RAM) ho\u1eb7c \u1ed5 c\u1ee9ng (HDD\/SSD).<\/td>\n<\/tr>\n<tr style=\"background: #f9fbff;\">\n<td style=\"padding: 12px; font-weight: bold;\">T\u1ed1c \u0111\u1ed9 ph\u1ea3n h\u1ed3i<\/td>\n<td style=\"padding: 12px;\">C\u1ef1c nhanh (Low Latency).<\/td>\n<td style=\"padding: 12px;\">Ch\u1eadm h\u01a1n \u0111\u00e1ng k\u1ec3 (High Latency) do Cache Penalty.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding: 12px; font-weight: bold;\">T\u00e1c \u0111\u1ed9ng \u0111\u1ebfn Server<\/td>\n<td style=\"padding: 12px;\">Gi\u1ea3m t\u1ea3i cho Server g\u1ed1c\/Database.<\/td>\n<td style=\"padding: 12px;\">T\u0103ng t\u1ea3i x\u1eed l\u00fd cho Server\/Database v\u00ec ph\u1ea3i truy v\u1ea5n l\u1ea1i.<\/td>\n<\/tr>\n<tr style=\"background: #f9fbff;\">\n<td style=\"padding: 12px; font-weight: bold;\">H\u00e0nh \u0111\u1ed9ng ti\u1ebfp theo<\/td>\n<td style=\"padding: 12px;\">CPU\/User nh\u1eadn d\u1eef li\u1ec7u v\u00e0 x\u1eed l\u00fd ngay.<\/td>\n<td style=\"padding: 12px;\">H\u1ec7 th\u1ed1ng fetch d\u1eef li\u1ec7u t\u1eeb ngu\u1ed3n g\u1ed1c, l\u01b0u v\u00e0o Cache r\u1ed3i m\u1edbi tr\u1ea3 v\u1ec1.<\/td>\n<\/tr>\n<tr>\n<td style=\"padding: 12px; font-weight: bold;\">Hi\u1ec7u n\u0103ng h\u1ec7 th\u1ed1ng<\/td>\n<td style=\"padding: 12px;\">T\u0103ng hi\u1ec7u n\u0103ng t\u1ed5ng th\u1ec3.<\/td>\n<td style=\"padding: 12px;\">Qu\u00e1 nhi\u1ec1u Miss s\u1ebd l\u00e0m gi\u1ea3m hi\u1ec7u n\u0103ng nghi\u00eam tr\u1ecdng.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Nh\u00ecn v\u00e0o b\u1ea3ng tr\u00ean, b\u1ea1n c\u00f3 th\u1ec3 th\u1ea5y m\u1ee5c ti\u00eau t\u1ed1i th\u01b0\u1ee3ng c\u1ee7a m\u1ecdi k\u1ef9 s\u01b0 h\u1ec7 th\u1ed1ng l\u00e0 t\u1ed1i \u0111a h\u00f3a Cache Hit v\u00e0 gi\u1ea3m thi\u1ec3u Cache Miss. Tuy nhi\u00ean, \u0111\u1ec3 l\u00e0m \u0111\u01b0\u1ee3c \u0111i\u1ec1u \u0111\u00f3, b\u1ea1n ph\u1ea3i bi\u1ebft nguy\u00ean nh\u00e2n g\u00e2y ra Cache Miss l\u00e0 g\u00ec.<\/p>\n<figure id=\"attachment_37286\" aria-describedby=\"caption-attachment-37286\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37286\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Phan-biet-Cache-Hit-va-Cache-Miss.webp\" alt=\"Ph\u00e2n bi\u1ec7t Cache Hit v\u00e0 Cache Miss\" width=\"700\" height=\"376\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Phan-biet-Cache-Hit-va-Cache-Miss.webp 700w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Phan-biet-Cache-Hit-va-Cache-Miss-300x161.webp 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-37286\" class=\"wp-caption-text\">Ph\u00e2n bi\u1ec7t Cache Hit v\u00e0 Cache Miss<\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"Phan-loai-cac-dang-Cache-Miss-Mo-hinh-3C\"><\/span>Ph\u00e2n lo\u1ea1i c\u00e1c d\u1ea1ng Cache Miss (M\u00f4 h\u00ecnh 3C)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Trong khoa h\u1ecdc m\u00e1y t\u00ednh, khi nghi\u00ean c\u1ee9u s\u00e2u v\u1ec1 ch\u1ee7 \u0111\u1ec1 <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong>, c\u00e1c k\u1ef9 s\u01b0 th\u01b0\u1eddng s\u1eed d\u1ee5ng m\u00f4 h\u00ecnh &#8220;3C&#8221; \u0111\u1ec3 ph\u00e2n lo\u1ea1i nguy\u00ean nh\u00e2n g\u00e2y ra Cache Miss. Vi\u1ec7c x\u00e1c \u0111\u1ecbnh \u0111\u00fang lo\u1ea1i Miss s\u1ebd gi\u00fap b\u1ea1n c\u00f3 ph\u01b0\u01a1ng \u00e1n kh\u1eafc ph\u1ee5c (&#8220;thu\u1ed1c ch\u1eefa&#8221;) ph\u00f9 h\u1ee3p.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"1-Compulsory-Miss-Miss-bat-buoc-Cold-Miss\"><\/span>1. Compulsory Miss (Miss b\u1eaft bu\u1ed9c \/ Cold Miss)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 lo\u1ea1i Miss x\u1ea3y ra \u1edf l\u1ea7n \u0111\u1ea7u ti\u00ean b\u1ea1n truy c\u1eadp v\u00e0o m\u1ed9t kh\u1ed1i d\u1eef li\u1ec7u. Khi b\u1ea1n v\u1eeba kh\u1edfi \u0111\u1ed9ng m\u00e1y t\u00ednh ho\u1eb7c v\u1eeba b\u1eadt m\u1ed9t \u1ee9ng d\u1ee5ng, b\u1ed9 nh\u1edb Cache ho\u00e0n to\u00e0n tr\u1ed1ng r\u1ed7ng (Cold Cache).<br \/>\nDo Cache ch\u01b0a c\u00f3 g\u00ec, n\u00ean ch\u1eafc ch\u1eafn l\u1ea7n truy c\u1eadp \u0111\u1ea7u ti\u00ean s\u1ebd l\u00e0 Cache Miss.<\/p>\n<ul>\n<li><strong>V\u00ed d\u1ee5:<\/strong> B\u1ea1n v\u1eeba deploy m\u1ed9t website m\u1edbi l\u00ean server c\u1ee7a InterData. Ng\u01b0\u1eddi d\u00f9ng \u0111\u1ea7u ti\u00ean truy c\u1eadp v\u00e0o trang ch\u1ee7 s\u1ebd g\u1eb7p t\u00ecnh tr\u1ea1ng load ch\u1eadm h\u01a1n m\u1ed9t ch\u00fat v\u00ec l\u00fac n\u00e0y Cache ch\u01b0a \u0111\u01b0\u1ee3c h\u00ecnh th\u00e0nh.<\/li>\n<li><strong>Gi\u1ea3i ph\u00e1p:<\/strong> Kh\u00f4ng th\u1ec3 lo\u1ea1i b\u1ecf ho\u00e0n to\u00e0n, nh\u01b0ng c\u00f3 th\u1ec3 gi\u1ea3m thi\u1ec3u t\u00e1c \u0111\u1ed9ng b\u1eb1ng k\u1ef9 thu\u1eadt &#8220;Cache Warming&#8221; (l\u00e0m n\u00f3ng Cache) &#8211; t\u1ee9c l\u00e0 ch\u1ee7 \u0111\u1ed9ng ch\u1ea1y script \u0111\u1ec3 load d\u1eef li\u1ec7u v\u00e0o Cache tr\u01b0\u1edbc khi m\u1edf cho ng\u01b0\u1eddi d\u00f9ng th\u1eadt truy c\u1eadp.<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"2-Capacity-Miss-Miss-do-dung-luong\"><\/span>2. Capacity Miss (Miss do dung l\u01b0\u1ee3ng)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Lo\u1ea1i Miss n\u00e0y x\u1ea3y ra khi b\u1ed9 nh\u1edb Cache \u0111\u00e3 b\u1ecb \u0111\u1ea7y. Cache c\u00f3 dung l\u01b0\u1ee3ng gi\u1edbi h\u1ea1n (v\u00ed d\u1ee5 L1 Cache ch\u1ec9 v\u00e0i ch\u1ee5c KB, Redis c\u00f3 th\u1ec3 v\u00e0i GB). Khi Cache \u0111\u1ea7y, \u0111\u1ec3 n\u1ea1p d\u1eef li\u1ec7u m\u1edbi v\u00e0o, h\u1ec7 th\u1ed1ng bu\u1ed9c ph\u1ea3i x\u00f3a b\u1edbt d\u1eef li\u1ec7u c\u0169. N\u1ebfu sau \u0111\u00f3 CPU l\u1ea1i c\u1ea7n \u0111\u1ebfn d\u1eef li\u1ec7u v\u1eeba b\u1ecb x\u00f3a, Cache Miss s\u1ebd x\u1ea3y ra.<\/p>\n<ul>\n<li><strong>V\u00ed d\u1ee5:<\/strong> C\u00e1i b\u00e0n c\u1ee7a \u0111\u1ea7u b\u1ebfp ch\u1ec9 \u0111\u1ec3 \u0111\u01b0\u1ee3c 5 l\u1ecd gia v\u1ecb. \u00d4ng c\u1ea7n d\u00f9ng l\u1ecd th\u1ee9 6, n\u00ean bu\u1ed9c ph\u1ea3i c\u1ea5t l\u1ecd th\u1ee9 1 \u0111i. L\u00e1t sau \u00f4ng l\u1ea1i c\u1ea7n l\u1ecd th\u1ee9 1, nh\u01b0ng n\u00f3 kh\u00f4ng c\u00f2n tr\u00ean b\u00e0n n\u1eefa.<\/li>\n<li><strong>Gi\u1ea3i ph\u00e1p:<\/strong> T\u0103ng dung l\u01b0\u1ee3ng Cache (n\u1ebfu c\u00f3 th\u1ec3) ho\u1eb7c t\u1ed1i \u01b0u h\u00f3a <a href=\"https:\/\/interdata.vn\/blog\/thuat-toan-algorithm\/\">thu\u1eadt to\u00e1n<\/a> thay th\u1ebf Cache (Cache Replacement Policy) \u0111\u1ec3 gi\u1eef l\u1ea1i nh\u1eefng d\u1eef li\u1ec7u quan tr\u1ecdng nh\u1ea5t.<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"3-Conflict-Miss-Miss-do-xung-dot\"><\/span>3. Conflict Miss (Miss do xung \u0111\u1ed9t)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 lo\u1ea1i Miss ph\u1ee9c t\u1ea1p nh\u1ea5t, th\u01b0\u1eddng x\u1ea3y ra trong c\u00e1c ki\u1ebfn tr\u00fac ph\u1ea7n c\u1ee9ng s\u1eed d\u1ee5ng k\u1ef9 thu\u1eadt \u00e1nh x\u1ea1 tr\u1ef1c ti\u1ebfp (Direct Mapped Cache) ho\u1eb7c t\u1eadp k\u1ebft h\u1ee3p (Set Associative Cache).<\/p>\n<p>Hi\u1ec3u \u0111\u01a1n gi\u1ea3n, b\u1ed9 nh\u1edb Cache \u0111\u01b0\u1ee3c chia th\u00e0nh c\u00e1c &#8220;ng\u0103n&#8221;. Quy t\u1eafc \u00e1nh x\u1ea1 quy \u0111\u1ecbnh r\u1eb1ng d\u1eef li\u1ec7u A ch\u1ec9 \u0111\u01b0\u1ee3c ph\u00e9p n\u1eb1m \u1edf ng\u0103n s\u1ed1 1. N\u1ebfu d\u1eef li\u1ec7u B c\u0169ng \u0111\u01b0\u1ee3c quy \u0111\u1ecbnh n\u1eb1m \u1edf ng\u0103n s\u1ed1 1, th\u00ec khi n\u1ea1p B v\u00e0o, A s\u1ebd b\u1ecb \u0111\u00e1 ra, d\u00f9 c\u00e1c ng\u0103n kh\u00e1c (2, 3, 4&#8230;) v\u1eabn c\u00f2n tr\u1ed1ng. Khi CPU quay l\u1ea1i t\u00ecm A, s\u1ebd x\u1ea3y ra Conflict Miss.<\/p>\n<ul>\n<li><strong>V\u00ed d\u1ee5:<\/strong> Trong b\u00e3i gi\u1eef xe, v\u00e9 xe c\u1ee7a b\u1ea1n quy \u0111\u1ecbnh b\u1ea1n ch\u1ec9 \u0111\u01b0\u1ee3c \u0111\u1ed7 \u1edf \u00f4 s\u1ed1 10. D\u00f9 b\u00e3i xe c\u00f2n tr\u1ed1ng 99 ch\u1ed7 kh\u00e1c, nh\u01b0ng n\u1ebfu \u00f4 s\u1ed1 10 \u0111\u00e3 c\u00f3 xe \u0111\u1ed7, b\u1ea1n kh\u00f4ng \u0111\u01b0\u1ee3c v\u00e0o.<\/li>\n<li><strong>Gi\u1ea3i ph\u00e1p:<\/strong> Thay \u0111\u1ed5i c\u1ea5u tr\u00fac Cache sang d\u1ea1ng Fully Associative (li\u00ean k\u1ebft \u0111\u1ea7y \u0111\u1ee7) ho\u1eb7c t\u0103ng \u0111\u1ed9 k\u1ebft h\u1ee3p (Associativity), nh\u01b0ng \u0111i\u1ec1u n\u00e0y ph\u1ee5 thu\u1ed9c v\u00e0o thi\u1ebft k\u1ebf ph\u1ea7n c\u1ee9ng.<\/li>\n<\/ul>\n<p>Vi\u1ec7c ph\u00e2n t\u00edch m\u00f4 h\u00ecnh 3C gi\u00fap c\u00e1c l\u1eadp tr\u00ecnh vi\u00ean hi\u1ec3u s\u00e2u s\u1eafc b\u1ea3n ch\u1ea5t <strong>Cache Hit v\u00e0 Cache Miss<\/strong>, t\u1eeb \u0111\u00f3 kh\u00f4ng \u0111\u1ed5 l\u1ed7i b\u1eeba b\u00e3i cho &#8220;m\u1ea1ng lag&#8221; hay &#8220;server y\u1ebfu&#8221;.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cach-tinh-Cache-Hit-Cache-Hit-Ratio\"><\/span>C\u00e1ch t\u00ednh Cache Hit (Cache Hit Ratio)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>T\u1ec9 l\u1ec7 cache hit \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1eb1ng c\u00e1ch l\u1ea5y s\u1ed1 l\u1ea7n h\u1ec7 th\u1ed1ng truy xu\u1ea5t d\u1eef li\u1ec7u th\u00e0nh c\u00f4ng t\u1eeb b\u1ed9 nh\u1edb cache chia cho t\u1ed5ng s\u1ed1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u, bao g\u1ed3m c\u1ea3 cache hit v\u00e0 cache miss.<\/p>\n<p><strong>C\u00f4ng th\u1ee9c<\/strong>: <strong>Cache Hit = S\u1ed1 l\u1ea7n Hit \/ (S\u1ed1 l\u1ea7n Hit + S\u1ed1 l\u1ea7n Miss)<\/strong><\/p>\n<p><strong>V\u00ed d\u1ee5<\/strong>: Gi\u1ea3 s\u1eed trong m\u1ed9t kho\u1ea3ng th\u1eddi gian nh\u1ea5t \u0111\u1ecbnh, h\u1ec7 th\u1ed1ng ghi nh\u1eadn 80 l\u1ea7n truy xu\u1ea5t d\u1eef li\u1ec7u th\u00e0nh c\u00f4ng t\u1eeb cache (cache hit) v\u00e0 20 l\u1ea7n kh\u00f4ng t\u00ecm th\u1ea5y d\u1eef li\u1ec7u trong cache (cache miss). Khi \u0111\u00f3, t\u1ec9 l\u1ec7 cache hit \u0111\u01b0\u1ee3c t\u00ednh nh\u01b0 sau:<\/p>\n<p><strong>Cache Hit = 80 \/ (80 + 20) = 80%<\/strong><\/p>\n<p><strong>Gi\u1ea3i th\u00edch<\/strong>: Cache hit \u0111\u1ea1t 80% c\u00f3 ngh\u0129a l\u00e0 80% y\u00eau c\u1ea7u d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u1ee5c v\u1ee5 tr\u1ef1c ti\u1ebfp t\u1eeb b\u1ed9 nh\u1edb cache, gi\u00fap h\u1ec7 th\u1ed1ng kh\u00f4ng c\u1ea7n truy xu\u1ea5t l\u1ea1i t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cach-tinh-Cache-Miss-Cache-Miss-Ratio\"><\/span>C\u00e1ch t\u00ednh Cache Miss (Cache Miss Ratio)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>T\u1ec9 l\u1ec7 cache miss \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng c\u00e1ch l\u1ea5y s\u1ed1 l\u1ea7n d\u1eef li\u1ec7u kh\u00f4ng t\u1ed3n t\u1ea1i trong cache (cache miss) chia cho t\u1ed5ng s\u1ed1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u.<\/p>\n<p><strong>C\u00f4ng th\u1ee9c<\/strong>: <strong>Cache Miss = S\u1ed1 l\u1ea7n Miss \/ (S\u1ed1 l\u1ea7n Hit + S\u1ed1 l\u1ea7n Miss)<\/strong><\/p>\n<p><strong>V\u00ed d\u1ee5<\/strong>: Trong c\u00f9ng kho\u1ea3ng th\u1eddi gian tr\u00ean, n\u1ebfu c\u00f3 20 l\u1ea7n d\u1eef li\u1ec7u kh\u00f4ng \u0111\u01b0\u1ee3c t\u00ecm th\u1ea5y trong cache (cache miss) v\u00e0 80 l\u1ea7n \u0111\u01b0\u1ee3c ph\u1ee5c v\u1ee5 t\u1eeb cache (cache hit), th\u00ec t\u1ec9 l\u1ec7 cache miss s\u1ebd \u0111\u01b0\u1ee3c t\u00ednh nh\u01b0 sau:<\/p>\n<p><strong>Cache Miss = 20 \/ (80 + 20) = 20%<\/strong><\/p>\n<p><strong>Gi\u1ea3i th\u00edch<\/strong>: T\u1ec9 l\u1ec7 miss l\u00e0 20%, \u0111\u1ed3ng ngh\u0129a v\u1edbi vi\u1ec7c 20% y\u00eau c\u1ea7u d\u1eef li\u1ec7u kh\u00f4ng th\u1ec3 x\u1eed l\u00fd t\u1eeb cache v\u00e0 bu\u1ed9c h\u1ec7 th\u1ed1ng ph\u1ea3i l\u1ea5y d\u1eef li\u1ec7u tr\u1ef1c ti\u1ebfp t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Tong-quan-ve-y-nghia-Cache-Hit-va-Cache-Miss\"><\/span>T\u1ed5ng quan v\u1ec1 \u00fd ngh\u0129a Cache Hit v\u00e0 Cache Miss<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<ul>\n<li><strong>Cache hit<\/strong> ph\u1ea3n \u00e1nh m\u1ee9c \u0111\u1ed9 hi\u1ec7u qu\u1ea3 c\u1ee7a h\u1ec7 th\u1ed1ng cache trong vi\u1ec7c ph\u1ee5c v\u1ee5 d\u1eef li\u1ec7u nhanh ch\u00f3ng.<\/li>\n<li><strong>Cache miss<\/strong> cho th\u1ea5y m\u1ee9c \u0111\u1ed9 h\u1ec7 th\u1ed1ng ph\u1ea3i ph\u1ee5 thu\u1ed9c v\u00e0o m\u00e1y ch\u1ee7 g\u1ed1c khi cache kh\u00f4ng \u0111\u00e1p \u1ee9ng \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u.<\/li>\n<\/ul>\n<p>Trong th\u1ef1c t\u1ebf, n\u1ebfu \u0111\u00e3 bi\u1ebft t\u1ec9 l\u1ec7 cache hit, b\u1ea1n c\u00f3 th\u1ec3 d\u1ec5 d\u00e0ng suy ra t\u1ec9 l\u1ec7 cache miss b\u1eb1ng c\u00e1ch:<\/p>\n<p>Cache Miss = 1 \u2013 Cache Hit (v\u00ec t\u1ed5ng t\u1ec9 l\u1ec7 hit v\u00e0 miss lu\u00f4n b\u1eb1ng 100%)<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Ti-le-Cache-Hit-va-Cache-Miss-ly-tuong-va-toc-do-tai-trang\"><\/span>T\u1ec9 l\u1ec7 Cache Hit v\u00e0 Cache Miss l\u00fd t\u01b0\u1edfng v\u00e0 t\u1ed1c \u0111\u1ed9 t\u1ea3i trang<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>T\u1ec9 l\u1ec7 cache hit v\u00e0 cache miss l\u00fd t\u01b0\u1edfng s\u1ebd kh\u00e1c nhau t\u00f9y theo <strong>lo\u1ea1i website<\/strong> v\u00e0 <strong>c\u1ea5u h\u00ecnh h\u1ec7 th\u1ed1ng<\/strong>, tuy nhi\u00ean th\u01b0\u1eddng c\u00f3 c\u00e1c m\u1ee9c tham kh\u1ea3o nh\u01b0 sau:<\/p>\n<ul>\n<li><strong>T\u1ec9 l\u1ec7 cache hit l\u00fd t\u01b0\u1edfng:<\/strong> Kho\u1ea3ng <strong>95% \u2013 99% (m\u1ee9c n\u00e0y mang t\u00ednh tham kh\u1ea3o v\u1edbi web content t\u0129nh)<\/strong> y\u00eau c\u1ea7u d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c ph\u1ee5c v\u1ee5 tr\u1ef1c ti\u1ebfp t\u1eeb cache m\u00e0 kh\u00f4ng c\u1ea7n truy xu\u1ea5t l\u1ea1i m\u00e1y ch\u1ee7 g\u1ed1c. M\u1ee9c hit cao cho th\u1ea5y cache \u0111ang ho\u1ea1t \u0111\u1ed9ng hi\u1ec7u qu\u1ea3, gi\u00fap t\u0103ng t\u1ed1c \u0111\u1ed9 t\u1ea3i trang v\u00e0 gi\u1ea3m t\u1ea3i cho server, t\u1eeb \u0111\u00f3 c\u1ea3i thi\u1ec7n tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng.<\/li>\n<li><strong>T\u1ec9 l\u1ec7 cache miss l\u00fd t\u01b0\u1edfng:<\/strong> Kho\u1ea3ng <strong>1% \u2013 5%<\/strong> y\u00eau c\u1ea7u kh\u00f4ng th\u1ec3 l\u1ea5y t\u1eeb cache v\u00e0 ph\u1ea3i truy xu\u1ea5t t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c. T\u1ec9 l\u1ec7 miss th\u1ea5p ph\u1ea3n \u00e1nh vi\u1ec7c d\u1eef li\u1ec7u \u0111\u00e3 \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef h\u1ee3p l\u00fd trong cache, gi\u00fap gi\u1ea3m \u0111\u1ed9 tr\u1ec5 khi ng\u01b0\u1eddi d\u00f9ng truy c\u1eadp l\u1ea1i n\u1ed9i dung quen thu\u1ed9c.<\/li>\n<\/ul>\n<p>Tuy nhi\u00ean, cache hit cao kh\u00f4ng \u0111\u1ed3ng ngh\u0129a lu\u00f4n t\u1ed1i \u01b0u. N\u1ebfu t\u1ec9 l\u1ec7 hit qu\u00e1 cao nh\u01b0ng kh\u00f4ng \u0111\u01b0\u1ee3c ki\u1ec3m so\u00e1t t\u1ed1t, h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 g\u1eb7p t\u00ecnh tr\u1ea1ng <strong>d\u1eef li\u1ec7u ch\u1eadm \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt<\/strong>. Ng\u01b0\u1ee3c l\u1ea1i, cache miss cao cho th\u1ea5y cache ch\u01b0a ph\u00e1t huy hi\u1ec7u qu\u1ea3, khi\u1ebfn th\u1eddi gian t\u1ea3i trang t\u0103ng v\u00e0 ti\u00eau t\u1ed1n th\u00eam t\u00e0i nguy\u00ean m\u00e1y ch\u1ee7, t\u1eeb \u0111\u00f3 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn hi\u1ec7u su\u1ea5t t\u1ed5ng th\u1ec3 c\u1ee7a website.<\/p>\n<figure id=\"attachment_37287\" aria-describedby=\"caption-attachment-37287\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37287\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Y-nghia-Cache-Hit-va-Cache-Miss.jpg\" alt=\"\u00dd ngh\u0129a Cache Hit v\u00e0 Cache Miss\" width=\"800\" height=\"500\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Y-nghia-Cache-Hit-va-Cache-Miss.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Y-nghia-Cache-Hit-va-Cache-Miss-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Y-nghia-Cache-Hit-va-Cache-Miss-768x480.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-37287\" class=\"wp-caption-text\">\u00dd ngh\u0129a Cache Hit v\u00e0 Cache Miss<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"Vi-sao-ti-le-Cache-Hit-va-Cache-Miss-ly-tuong-lai-quan-trong\"><\/span>V\u00ec sao t\u1ec9 l\u1ec7 Cache Hit v\u00e0 Cache Miss l\u00fd t\u01b0\u1edfng l\u1ea1i quan tr\u1ecdng?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Vi\u1ec7c duy tr\u00ec <strong>cache hit cao v\u00e0 cache miss th\u1ea5p<\/strong> gi\u00fap:<\/p>\n<ul>\n<li>T\u0103ng t\u1ed1c \u0111\u1ed9 t\u1ea3i trang<\/li>\n<li>Gi\u1ea3m t\u00e0i nguy\u00ean ti\u00eau th\u1ee5 c\u1ee7a m\u00e1y ch\u1ee7<\/li>\n<li>N\u00e2ng cao hi\u1ec7u su\u1ea5t t\u1ed5ng th\u1ec3 c\u1ee7a h\u1ec7 th\u1ed1ng<\/li>\n<\/ul>\n<p>D\u00f9 v\u1eady, v\u1edbi c\u00e1c website c\u00f3 <strong>n\u1ed9i dung thay \u0111\u1ed5i th\u01b0\u1eddng xuy\u00ean<\/strong> ho\u1eb7c ch\u1ee9a nhi\u1ec1u d\u1eef li\u1ec7u \u0111\u1ed9ng, vi\u1ec7c \u0111\u1ea1t cache hit 100% l\u00e0 <strong>kh\u00f4ng kh\u1ea3 thi v\u00e0 c\u0169ng kh\u00f4ng c\u1ea7n thi\u1ebft<\/strong>.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Anh-huong-cua-Cache-Hit-va-Cache-Miss-den-toc-do-tai-trang\"><\/span>\u1ea2nh h\u01b0\u1edfng c\u1ee7a Cache Hit v\u00e0 Cache Miss \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 t\u1ea3i trang<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul>\n<li><strong>Cache hit cao (95% \u2013 99%)<\/strong> gi\u00fap c\u1ea3i thi\u1ec7n t\u1ed1c \u0111\u1ed9 t\u1ea3i trang do d\u1eef li\u1ec7u \u0111\u00e3 s\u1eb5n c\u00f3 trong cache v\u00e0 kh\u00f4ng c\u1ea7n truy xu\u1ea5t l\u1ea1i t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c. \u0110i\u1ec1u n\u00e0y h\u1ed7 tr\u1ee3 c\u1ea3i thi\u1ec7n <strong><a href=\"https:\/\/interdata.vn\/blog\/nhan-cpu-la-gi\/\">Core<\/a> Web Vitals<\/strong>, \u0111\u1eb7c bi\u1ec7t l\u00e0 ch\u1ec9 s\u1ed1 <strong>LCP (Largest Contentful Paint)<\/strong>, qua \u0111\u00f3 n\u00e2ng cao tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 h\u1ed7 tr\u1ee3 SEO t\u1ed1t h\u01a1n.<\/li>\n<li><strong>Cache miss cao (t\u1eeb 10% tr\u1edf l\u00ean)<\/strong> l\u00e0m t\u0103ng \u0111\u1ed9 tr\u1ec5 v\u00ec h\u1ec7 th\u1ed1ng ph\u1ea3i l\u1ea5y d\u1eef li\u1ec7u t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c. \u0110i\u1ec1u n\u00e0y kh\u00f4ng ch\u1ec9 khi\u1ebfn trang t\u1ea3i ch\u1eadm h\u01a1n m\u00e0 c\u00f2n l\u00e0m t\u0103ng t\u1ea3i m\u00e1y ch\u1ee7, ti\u00eau t\u1ed1n t\u00e0i nguy\u00ean v\u00e0 c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn <strong>t\u1ef7 l\u1ec7 tho\u00e1t trang (bounce rate) cao<\/strong>.<\/li>\n<\/ul>\n<p><strong>T\u00f3m l\u1ea1i:<\/strong><\/p>\n<ul>\n<li><strong>T\u1ec9 l\u1ec7 cache hit cao<\/strong> gi\u00fap c\u1ea3i thi\u1ec7n t\u1ed1c \u0111\u1ed9 t\u1ea3i trang, n\u00e2ng cao tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 h\u1ed7 tr\u1ee3 t\u1ed1t cho Core Web Vitals c\u0169ng nh\u01b0 SEO.<\/li>\n<li><strong>T\u1ec9 l\u1ec7 cache miss th\u1ea5p<\/strong> gi\u00fap gi\u1ea3m t\u1ea3i cho m\u00e1y ch\u1ee7 v\u00e0 duy tr\u00ec hi\u1ec7u su\u1ea5t \u1ed5n \u0111\u1ecbnh cho website.<\/li>\n<li><strong>Vi\u1ec7c t\u1ed1i \u01b0u cache hit v\u00e0 cache miss<\/strong> l\u00e0 m\u1ed9t y\u1ebfu t\u1ed1 quan tr\u1ecdng \u0111\u1ec3 t\u0103ng t\u1ed1c website, c\u1ea3i thi\u1ec7n hi\u1ec7u n\u0103ng h\u1ec7 th\u1ed1ng v\u00e0 \u0111\u1ea1t k\u1ebft qu\u1ea3 SEO b\u1ec1n v\u1eefng.<\/li>\n<\/ul>\n<h2><span class=\"ez-toc-section\" id=\"Khi-nao-Cache-Hit-cao-nhung-he-thong-van-cham\"><\/span>Khi n\u00e0o Cache Hit cao nh\u01b0ng h\u1ec7 th\u1ed1ng v\u1eabn ch\u1eadm?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u0110\u00e2y l\u00e0 m\u1ed9t c\u00e2u h\u1ecfi &#8220;n\u00e2ng cao&#8221; m\u00e0 \u00edt t\u00e0i li\u1ec7u c\u01a1 b\u1ea3n v\u1ec1 <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong> \u0111\u1ec1 c\u1eadp \u0111\u1ebfn. Nhi\u1ec1u Developer v\u1ed7 ng\u1ef1c t\u1ef1 h\u00e0o khi th\u1ea5y ch\u1ec9 s\u1ed1 Cache Hit Ratio \u0111\u1ea1t 99%, nh\u01b0ng ng\u01b0\u1eddi d\u00f9ng v\u1eabn than phi\u1ec1n web load ch\u1eadm. T\u1ea1i sao v\u1eady?<\/p>\n<h3><span class=\"ez-toc-section\" id=\"1-Cache-Layer-dat-sai-vi-tri-hoac-do-tre-mang-Network-Latency\"><\/span>1. Cache Layer \u0111\u1eb7t sai v\u1ecb tr\u00ed ho\u1eb7c \u0111\u1ed9 tr\u1ec5 m\u1ea1ng (Network Latency)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Gi\u1ea3 s\u1eed b\u1ea1n d\u00f9ng Redis l\u00e0m cache, nh\u01b0ng Redis server l\u1ea1i \u0111\u1eb7t \u1edf M\u1ef9 trong khi Web server v\u00e0 ng\u01b0\u1eddi d\u00f9ng \u1edf Vi\u1ec7t Nam. D\u00f9 Cache Hit x\u1ea3y ra (t\u00ecm th\u1ea5y d\u1eef li\u1ec7u trong Redis), nh\u01b0ng th\u1eddi gian \u0111\u1ec3 g\u00f3i tin \u0111i t\u1eeb M\u1ef9 v\u1ec1 Vi\u1ec7t Nam m\u1ea5t t\u1edbi 200ms. Trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y, vi\u1ec7c \u0111\u1ecdc tr\u1ef1c ti\u1ebfp t\u1eeb database n\u1ed9i b\u1ed9 c\u00f3 khi c\u00f2n nhanh h\u01a1n.<\/p>\n<p><strong>B\u00e0i h\u1ecdc:<\/strong> Cache ph\u1ea3i \u0111\u1eb7t c\u00e0ng g\u1ea7n n\u01a1i x\u1eed l\u00fd (Compute Unit) c\u00e0ng t\u1ed1t.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"2-Van-de-tuan-tu-hoa-du-lieu-Serialization-Overhead\"><\/span>2. V\u1ea5n \u0111\u1ec1 tu\u1ea7n t\u1ef1 h\u00f3a d\u1eef li\u1ec7u (Serialization Overhead)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Khi l\u01b0u object v\u00e0o Cache (nh\u01b0 Redis), b\u1ea1n ph\u1ea3i bi\u1ebfn \u0111\u1ed5i n\u00f3 th\u00e0nh chu\u1ed7i (JSON, Protobuf&#8230;). Khi l\u1ea5y ra, b\u1ea1n ph\u1ea3i gi\u1ea3i m\u00e3 (Deserialize) ng\u01b0\u1ee3c l\u1ea1i. N\u1ebfu object c\u1ee7a b\u1ea1n qu\u00e1 l\u1edbn (v\u00ed d\u1ee5 m\u1ed9t danh s\u00e1ch 10.000 s\u1ea3n ph\u1ea9m), th\u1eddi gian CPU d\u00f9ng \u0111\u1ec3 \u0111\u00f3ng g\u00f3i v\u00e0 gi\u1ea3i n\u00e9n d\u1eef li\u1ec7u n\u00e0y c\u00f3 th\u1ec3 c\u00f2n l\u00e2u h\u01a1n c\u1ea3 th\u1eddi gian query database.<\/p>\n<p><strong>B\u00e0i h\u1ecdc:<\/strong> Ch\u1ec9 cache nh\u1eefng g\u00ec th\u1ef1c s\u1ef1 c\u1ea7n thi\u1ebft, tr\u00e1nh cache c\u00e1c object qu\u00e1 kh\u1ed5 (Big Keys).<\/p>\n<h3><span class=\"ez-toc-section\" id=\"3-Cache-Stampede-Hieu-ung-dam-dong\"><\/span>3. Cache Stampede (Hi\u1ec7u \u1ee9ng \u0111\u00e1m \u0111\u00f4ng)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 hi\u1ec7n t\u01b0\u1ee3ng khi m\u1ed9t key cache quan tr\u1ecdng (v\u00ed d\u1ee5: th\u00f4ng tin trang ch\u1ee7) b\u1ecb h\u1ebft h\u1ea1n (expire) \u0111\u00fang l\u00fac c\u00f3 h\u00e0ng ngh\u00ecn user \u0111ang truy c\u1eadp.<\/p>\n<p>T\u1ea5t c\u1ea3 h\u00e0ng ngh\u00ecn request n\u00e0y \u0111\u1ec1u nh\u1eadn k\u1ebft qu\u1ea3 Cache Miss c\u00f9ng m\u1ed9t l\u00fac. Ch\u00fang \u0111\u1ed3ng lo\u1ea1t lao xu\u1ed1ng Database \u0111\u1ec3 l\u1ea5y d\u1eef li\u1ec7u, khi\u1ebfn Database b\u1ecb qu\u00e1 t\u1ea3i v\u00e0 s\u1eadp ngay l\u1eadp t\u1ee9c (d\u00f9 tr\u01b0\u1edbc \u0111\u00f3 1 gi\u00e2y m\u1ecdi th\u1ee9 v\u1eabn m\u01b0\u1ee3t).<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cach-cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao\"><\/span>C\u00e1ch c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t cache khi t\u1ec9 l\u1ec7 Cache Miss cao<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Khi cache Miss x\u1ea3y ra v\u1edbi t\u1ea7n su\u1ea5t l\u1edbn, website s\u1ebd b\u1ecb \u1ea3nh h\u01b0\u1edfng r\u00f5 r\u1ec7t v\u1ec1 hi\u1ec7u su\u1ea5t do h\u1ec7 th\u1ed1ng ph\u1ea3i li\u00ean t\u1ee5c truy xu\u1ea5t d\u1eef li\u1ec7u t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c thay v\u00ec s\u1eed d\u1ee5ng d\u1eef li\u1ec7u \u0111\u00e3 l\u01b0u s\u1eb5n trong cache. \u0110i\u1ec1u n\u00e0y l\u00e0m t\u0103ng \u0111\u1ed9 tr\u1ec5, ti\u00eau t\u1ed1n t\u00e0i nguy\u00ean v\u00e0 khi\u1ebfn tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng k\u00e9m \u0111i.<\/p>\n<p>D\u01b0\u1edbi \u0111\u00e2y l\u00e0 c\u00e1c ph\u01b0\u01a1ng ph\u00e1p ph\u1ed5 bi\u1ebfn gi\u00fap c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t cache v\u00e0 gi\u1ea3m cache Miss, t\u1eeb \u0111\u00f3 t\u0103ng t\u1ed1c \u0111\u1ed9 t\u1ea3i trang v\u00e0 t\u1ed1i \u01b0u tr\u1ea3i nghi\u1ec7m t\u1ed5ng th\u1ec3.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"1-Tang-dung-luong-bo-nho-cache\"><\/span>1. T\u0103ng dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>Khi k\u00edch th\u01b0\u1edbc cache qu\u00e1 nh\u1ecf, h\u1ec7 th\u1ed1ng ch\u1ec9 c\u00f3 th\u1ec3 l\u01b0u tr\u1eef m\u1ed9t ph\u1ea7n d\u1eef li\u1ec7u h\u1ea1n ch\u1ebf. \u0110i\u1ec1u n\u00e0y khi\u1ebfn nhi\u1ec1u y\u00eau c\u1ea7u kh\u00f4ng \u0111\u01b0\u1ee3c ph\u1ee5c v\u1ee5 t\u1eeb cache v\u00e0 bu\u1ed9c ph\u1ea3i truy xu\u1ea5t l\u1ea1i t\u1eeb m\u00e1y ch\u1ee7 g\u1ed1c, l\u00e0m gia t\u0103ng cache Miss.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>M\u1edf r\u1ed9ng dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb cache \u0111\u1ec3 l\u01b0u tr\u1eef \u0111\u01b0\u1ee3c nhi\u1ec1u d\u1eef li\u1ec7u h\u01a1n. Khi cache ch\u1ee9a nhi\u1ec1u n\u1ed9i dung h\u01a1n, kh\u1ea3 n\u0103ng \u0111\u00e1p \u1ee9ng c\u00e1c y\u00eau c\u1ea7u l\u1eb7p l\u1ea1i s\u1ebd cao h\u01a1n, t\u1eeb \u0111\u00f3 gi\u1ea3m cache Miss.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>N\u1ebfu h\u1ec7 th\u1ed1ng cache hi\u1ec7n t\u1ea1i ch\u1ec9 l\u01b0u \u0111\u01b0\u1ee3c d\u1eef li\u1ec7u c\u1ee7a 1.000 trang, vi\u1ec7c m\u1edf r\u1ed9ng dung l\u01b0\u1ee3ng l\u00ean 5.000 trang s\u1ebd gi\u00fap gi\u1eef l\u1ea1i nhi\u1ec1u n\u1ed9i dung h\u01a1n trong cache v\u00e0 gi\u1ea3m \u0111\u00e1ng k\u1ec3 s\u1ed1 l\u1ea7n cache Miss.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"2-Ap-dung-cache-dong-Dynamic-Caching\"><\/span>2. \u00c1p d\u1ee5ng cache \u0111\u1ed9ng (Dynamic Caching)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>C\u00e1c website c\u00f3 n\u1ed9i dung thay \u0111\u1ed5i th\u01b0\u1eddng xuy\u00ean th\u01b0\u1eddng g\u1eb7p kh\u00f3 kh\u0103n khi cache theo c\u00e1ch truy\u1ec1n th\u1ed1ng, d\u1eabn \u0111\u1ebfn t\u1ec9 l\u1ec7 cache Miss cao.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>S\u1eed d\u1ee5ng cache \u0111\u1ed9ng, cho ph\u00e9p l\u01b0u tr\u1eef c\u00e1c ph\u1ea7n d\u1eef li\u1ec7u thay \u0111\u1ed5i th\u01b0\u1eddng xuy\u00ean nh\u01b0ng v\u1eabn c\u00f3 c\u01a1 ch\u1ebf l\u00e0m m\u1edbi \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o t\u00ednh c\u1eadp nh\u1eadt. M\u1ed9t s\u1ed1 n\u1ed9i dung nh\u01b0 k\u1ebft qu\u1ea3 t\u00ecm ki\u1ebfm ho\u1eb7c trang c\u00f3 d\u1eef li\u1ec7u c\u1eadp nh\u1eadt li\u00ean t\u1ee5c v\u1eabn c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c cache theo c\u00e1ch n\u00e0y.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>Tri\u1ec3n khai Edge caching tr\u00ean CDN \u0111\u1ec3 l\u01b0u tr\u1eef n\u1ed9i dung t\u0129nh t\u1ea1i c\u00e1c m\u00e1y ch\u1ee7 g\u1ea7n ng\u01b0\u1eddi d\u00f9ng, t\u1eeb \u0111\u00f3 gi\u1ea3m s\u1ed1 y\u00eau c\u1ea7u d\u1eef li\u1ec7u \u0111\u1ed9ng ph\u1ea3i g\u1eedi v\u1ec1 m\u00e1y ch\u1ee7 ch\u00ednh.<\/p>\n<figure id=\"attachment_37288\" aria-describedby=\"caption-attachment-37288\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-37288\" src=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao.jpg\" alt=\"C\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t cache khi t\u1ec9 l\u1ec7 Cache Miss cao\" width=\"800\" height=\"500\" title=\"\" srcset=\"https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao.jpg 800w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao-300x188.jpg 300w, https:\/\/interdata.vn\/blog\/wp-content\/uploads\/2025\/12\/Cai-thien-hieu-suat-cache-khi-ti-le-Cache-Miss-cao-768x480.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-37288\" class=\"wp-caption-text\">C\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t cache khi t\u1ec9 l\u1ec7 Cache Miss cao<\/figcaption><\/figure>\n<h3><span class=\"ez-toc-section\" id=\"3-Dieu-chinh-va-toi-uu-cau-hinh-cache\"><\/span>3. \u0110i\u1ec1u ch\u1ec9nh v\u00e0 t\u1ed1i \u01b0u c\u1ea5u h\u00ecnh cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>C\u1ea5u h\u00ecnh cache ch\u01b0a ph\u00f9 h\u1ee3p, ch\u1eb3ng h\u1ea1n nh\u01b0 th\u1eddi gian s\u1ed1ng (TTL) qu\u00e1 ng\u1eafn, c\u00f3 th\u1ec3 khi\u1ebfn d\u1eef li\u1ec7u b\u1ecb x\u00f3a kh\u1ecfi cache qu\u00e1 nhanh v\u00e0 l\u00e0m t\u0103ng cache Miss.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>Tinh ch\u1ec9nh c\u1ea5u h\u00ecnh cache b\u1eb1ng c\u00e1ch t\u0103ng TTL ho\u1eb7c \u0111i\u1ec1u ch\u1ec9nh c\u00e1ch l\u01b0u tr\u1eef d\u1eef li\u1ec7u. C\u00e1c d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c truy c\u1eadp th\u01b0\u1eddng xuy\u00ean n\u00ean \u0111\u01b0\u1ee3c gi\u1eef trong cache l\u00e2u h\u01a1n \u0111\u1ec3 gi\u1ea3m kh\u1ea3 n\u0103ng cache Miss.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>T\u0103ng TTL cho h\u00ecnh \u1ea3nh, CSS, JavaScript ho\u1eb7c c\u00e1c trang ph\u1ed5 bi\u1ebfn gi\u00fap d\u1eef li\u1ec7u kh\u00f4ng b\u1ecb lo\u1ea1i b\u1ecf s\u1edbm, t\u1eeb \u0111\u00f3 t\u0103ng kh\u1ea3 n\u0103ng \u0111\u01b0\u1ee3c ph\u1ee5c v\u1ee5 t\u1eeb cache khi ng\u01b0\u1eddi d\u00f9ng truy c\u1eadp l\u1ea1i.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"4-Toi-uu-hoa-he-thong-Content-Delivery-Network-CDN\"><\/span>4. T\u1ed1i \u01b0u h\u00f3a h\u1ec7 th\u1ed1ng Content Delivery Network (CDN)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>CDN gi\u00fap ph\u00e2n ph\u1ed1i n\u1ed9i dung t\u1eeb c\u00e1c m\u00e1y ch\u1ee7 \u0111\u1eb7t g\u1ea7n ng\u01b0\u1eddi d\u00f9ng h\u01a1n, nh\u1edd \u0111\u00f3 gi\u1ea3m \u0111\u1ed9 tr\u1ec5 v\u00e0 c\u1ea3i thi\u1ec7n t\u1ec9 l\u1ec7 cache Hit.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>T\u1ed1i \u01b0u c\u1ea5u h\u00ecnh CDN b\u1eb1ng c\u00e1ch t\u0103ng c\u01b0\u1eddng Edge caching v\u00e0 \u0111\u1ea3m b\u1ea3o n\u1ed9i dung \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef, ph\u00e2n ph\u1ed1i t\u1eeb c\u00e1c node g\u1ea7n ng\u01b0\u1eddi d\u00f9ng. \u0110i\u1ec1u n\u00e0y gi\u00fap gi\u1ea3m cache Miss v\u00e0 t\u0103ng t\u1ed1c \u0111\u1ed9 t\u1ea3i trang.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>S\u1eed d\u1ee5ng CDN \u0111\u1ec3 ph\u00e2n ph\u1ed1i c\u00e1c t\u00e0i nguy\u00ean t\u0129nh nh\u01b0 h\u00ecnh \u1ea3nh, CSS v\u00e0 JavaScript nh\u1eb1m gi\u1ea3m t\u1ea3i cho m\u00e1y ch\u1ee7 ch\u00ednh v\u00e0 c\u1ea3i thi\u1ec7n hi\u1ec7u qu\u1ea3 cache.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"5-Ra-soat-va-khac-phuc-loi-trong-cau-hinh-cache\"><\/span>5. R\u00e0 so\u00e1t v\u00e0 kh\u1eafc ph\u1ee5c l\u1ed7i trong c\u1ea5u h\u00ecnh cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>C\u00e1c l\u1ed7i c\u1ea5u h\u00ecnh c\u00f3 th\u1ec3 khi\u1ebfn cache kh\u00f4ng ho\u1ea1t \u0111\u1ed9ng \u0111\u00fang nh\u01b0 mong \u0111\u1ee3i, l\u00e0m t\u0103ng s\u1ed1 l\u01b0\u1ee3ng cache Miss.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>Ki\u1ec3m tra l\u1ea1i to\u00e0n b\u1ed9 c\u1ea5u h\u00ecnh cache, bao g\u1ed3m cache key, thi\u1ebft l\u1eadp header v\u00e0 c\u01a1 ch\u1ebf cache purging. \u0110\u1ea3m b\u1ea3o d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef ch\u00ednh x\u00e1c v\u00e0 kh\u00f4ng b\u1ecb m\u1ea5t khi c\u1ea7n s\u1eed d\u1ee5ng.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>\u0110\u1ea3m b\u1ea3o c\u00e1c HTTP header nh\u01b0 <code>Cache-Control<\/code> v\u00e0 <code>ETag<\/code> \u0111\u01b0\u1ee3c c\u1ea5u h\u00ecnh \u0111\u00fang \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh c\u00e1ch d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef, l\u00e0m m\u1edbi v\u00e0 t\u00e1i s\u1eed d\u1ee5ng trong cache.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"6-Chon-cong-cu-cache-phu-hop-voi-he-thong\"><\/span>6. Ch\u1ecdn c\u00f4ng c\u1ee5 cache ph\u00f9 h\u1ee3p v\u1edbi h\u1ec7 th\u1ed1ng<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>Vi\u1ec7c s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5 cache kh\u00f4ng ph\u00f9 h\u1ee3p v\u1edbi nhu c\u1ea7u th\u1ef1c t\u1ebf c\u1ee7a h\u1ec7 th\u1ed1ng c\u00f3 th\u1ec3 khi\u1ebfn hi\u1ec7u su\u1ea5t kh\u00f4ng \u0111\u1ea1t k\u1ef3 v\u1ecdng v\u00e0 l\u00e0m t\u0103ng cache Miss.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>L\u1ef1a ch\u1ecdn gi\u1ea3i ph\u00e1p cache ph\u00f9 h\u1ee3p v\u1edbi m\u00f4 h\u00ecnh website, ch\u1eb3ng h\u1ea1n nh\u01b0 Varnish, Memcached ho\u1eb7c Redis, nh\u1eb1m n\u00e2ng cao kh\u1ea3 n\u0103ng l\u01b0u tr\u1eef v\u00e0 ph\u00e2n ph\u1ed1i d\u1eef li\u1ec7u nhanh ch\u00f3ng.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>\u00c1p d\u1ee5ng Varnish Cache cho c\u00e1c website c\u00f3 l\u01b0u l\u01b0\u1ee3ng truy c\u1eadp l\u1edbn gi\u00fap t\u0103ng t\u1ed1c \u0111\u1ed9 ph\u1ea3n h\u1ed3i v\u00e0 gi\u1ea3m cache Miss hi\u1ec7u qu\u1ea3.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"7-Toi-uu-ma-nguon-va-cau-truc-website\"><\/span>7. T\u1ed1i \u01b0u m\u00e3 ngu\u1ed3n v\u00e0 c\u1ea5u tr\u00fac website<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>M\u00e3 ngu\u1ed3n ch\u01b0a \u0111\u01b0\u1ee3c t\u1ed1i \u01b0u c\u00f3 th\u1ec3 khi\u1ebfn t\u00e0i nguy\u00ean kh\u00f4ng \u0111\u01b0\u1ee3c cache hi\u1ec7u qu\u1ea3, l\u00e0m gi\u1ea3m kh\u1ea3 n\u0103ng t\u1eadn d\u1ee5ng cache.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>Tinh g\u1ecdn m\u00e3 ngu\u1ed3n, h\u1ea1n ch\u1ebf t\u00e0i nguy\u00ean \u0111\u1ed9ng kh\u00f4ng c\u1ea7n thi\u1ebft, gi\u1ea3m s\u1ed1 l\u01b0\u1ee3ng y\u00eau c\u1ea7u HTTP v\u00e0 \u0111\u1ea3m b\u1ea3o c\u00e1c t\u00e0i nguy\u00ean nh\u01b0 h\u00ecnh \u1ea3nh, CSS, JavaScript \u0111\u01b0\u1ee3c t\u1ea3i v\u00e0 cache h\u1ee3p l\u00fd.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>G\u1ed9p nhi\u1ec1u t\u1ec7p JavaScript v\u00e0 CSS th\u00e0nh m\u1ed9t t\u1ec7p duy nh\u1ea5t \u0111\u1ec3 gi\u1ea3m s\u1ed1 request HTTP v\u00e0 c\u1ea3i thi\u1ec7n kh\u1ea3 n\u0103ng cache.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"8-Ap-dung-cac-ky-thuat-cache-nang-cao\"><\/span>8. \u00c1p d\u1ee5ng c\u00e1c k\u1ef9 thu\u1eadt cache n\u00e2ng cao<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><strong>L\u00fd do: <\/strong>Trong m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p, c\u00e1c ph\u01b0\u01a1ng ph\u00e1p cache c\u01a1 b\u1ea3n kh\u00f4ng \u0111\u1ee7 \u0111\u1ec3 x\u1eed l\u00fd kh\u1ed1i l\u01b0\u1ee3ng d\u1eef li\u1ec7u l\u1edbn ho\u1eb7c c\u00e1c y\u00eau c\u1ea7u ph\u1ee9c t\u1ea1p \u0111\u00f2i h\u1ecfi \u0111\u1ed9 ch\u00ednh x\u00e1c cao.<\/p>\n<p><strong>C\u00e1ch th\u1ef1c hi\u1ec7n: <\/strong>Tri\u1ec3n khai c\u00e1c k\u1ef9 thu\u1eadt cache n\u00e2ng cao nh\u01b0 cache ph\u00e2n t\u00e1n ho\u1eb7c cache theo ng\u1eef c\u1ea3nh \u0111\u1ec3 x\u1eed l\u00fd t\u1ed1t h\u01a1n c\u00e1c y\u00eau c\u1ea7u ph\u1ee9c t\u1ea1p, t\u1eeb \u0111\u00f3 gi\u1ea3m cache Miss v\u00e0 c\u1ea3i thi\u1ec7n t\u1ed1c \u0111\u1ed9 t\u1ea3i trang.<\/p>\n<p><strong>V\u00ed d\u1ee5: <\/strong>Thi\u1ebft l\u1eadp h\u1ec7 th\u1ed1ng cache ph\u00e2n t\u00e1n \u0111\u1ec3 \u0111\u1ed3ng b\u1ed9 d\u1eef li\u1ec7u cache gi\u1eefa nhi\u1ec1u m\u00e1y ch\u1ee7, \u0111\u1ea3m b\u1ea3o d\u1eef li\u1ec7u lu\u00f4n s\u1eb5n s\u00e0ng khi c\u00f3 y\u00eau c\u1ea7u.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Cac-van-de-thuong-gap-khi-trien-khai-Cache-trong-he-thong\"><\/span>C\u00e1c v\u1ea5n \u0111\u1ec1 th\u01b0\u1eddng g\u1eb7p khi tri\u1ec3n khai Cache trong h\u1ec7 th\u1ed1ng<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"Bai-toan-dong-bo-du-lieu-Cache-Invalidation\"><\/span>B\u00e0i to\u00e1n \u0111\u1ed3ng b\u1ed9 d\u1eef li\u1ec7u (Cache Invalidation)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 m\u1ed9t trong nh\u1eefng th\u00e1ch th\u1ee9c l\u1edbn nh\u1ea5t khi s\u1eed d\u1ee5ng cache. N\u1ebfu d\u1eef li\u1ec7u g\u1ed1c \u0111\u00e3 thay \u0111\u1ed5i nh\u01b0ng cache kh\u00f4ng \u0111\u01b0\u1ee3c l\u00e0m m\u1edbi k\u1ecbp th\u1eddi, ng\u01b0\u1eddi d\u00f9ng c\u00f3 th\u1ec3 nh\u1eadn ph\u1ea3i th\u00f4ng tin c\u0169 ho\u1eb7c kh\u00f4ng ch\u00ednh x\u00e1c. \u0110\u1ec3 h\u1ea1n ch\u1ebf v\u1ea5n \u0111\u1ec1 n\u00e0y, h\u1ec7 th\u1ed1ng th\u01b0\u1eddng \u00e1p d\u1ee5ng c\u01a1 ch\u1ebf x\u00f3a cache c\u00f3 ch\u1ecdn l\u1ecdc ho\u1eb7c thi\u1ebft l\u1eadp th\u1eddi gian h\u1ebft h\u1ea1n (TTL) h\u1ee3p l\u00fd nh\u1eb1m \u0111\u1ea3m b\u1ea3o d\u1eef li\u1ec7u lu\u00f4n \u0111\u01b0\u1ee3c c\u1eadp nh\u1eadt.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Gioi-han-dung-luong-bo-nho-cache\"><\/span>Gi\u1edbi h\u1ea1n dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Cache c\u00f3 dung l\u01b0\u1ee3ng c\u00e0ng l\u1edbn th\u00ec kh\u1ea3 n\u0103ng l\u01b0u tr\u1eef d\u1eef li\u1ec7u c\u00e0ng cao, nh\u01b0ng \u0111\u1ed3ng th\u1eddi c\u0169ng ti\u00eau t\u1ed1n nhi\u1ec1u t\u00e0i nguy\u00ean ph\u1ea7n c\u1ee9ng h\u01a1n. V\u00ec v\u1eady, doanh nghi\u1ec7p c\u1ea7n c\u00e2n \u0111\u1ed1i dung l\u01b0\u1ee3ng cache sao cho ph\u00f9 h\u1ee3p v\u1edbi quy m\u00f4 v\u00e0 nhu c\u1ea7u s\u1eed d\u1ee5ng c\u1ee7a h\u1ec7 th\u1ed1ng.<\/p>\n<p>M\u1ed9t c\u00e1ch ti\u1ebfp c\u1eadn ph\u1ed5 bi\u1ebfn l\u00e0 ch\u1ec9 cache c\u00e1c d\u1eef li\u1ec7u \u201cn\u00f3ng\u201d, t\u1ee9c nh\u1eefng n\u1ed9i dung \u0111\u01b0\u1ee3c truy c\u1eadp th\u01b0\u1eddng xuy\u00ean, thay v\u00ec l\u01b0u tr\u1eef to\u00e0n b\u1ed9 d\u1eef li\u1ec7u.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Chi-phi-quan-ly-va-bao-tri-he-thong-cache\"><\/span>Chi ph\u00ed qu\u1ea3n l\u00fd v\u00e0 b\u1ea3o tr\u00ec h\u1ec7 th\u1ed1ng cache<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>M\u1eb7c d\u00f9 cache mang l\u1ea1i l\u1ee3i \u00edch l\u1edbn v\u1ec1 hi\u1ec7u n\u0103ng, nh\u01b0ng vi\u1ec7c tri\u1ec3n khai, theo d\u00f5i v\u00e0 t\u1ed1i \u01b0u cache c\u0169ng ph\u00e1t sinh chi ph\u00ed k\u1ef9 thu\u1eadt nh\u1ea5t \u0111\u1ecbnh. C\u00e1c h\u1ec7 th\u1ed1ng cache ph\u1ee9c t\u1ea1p, ch\u1eb3ng h\u1ea1n nh\u01b0 cache ph\u00e2n t\u00e1n ho\u1eb7c nhi\u1ec1u t\u1ea7ng, th\u01b0\u1eddng y\u00eau c\u1ea7u c\u00f4ng c\u1ee5 qu\u1ea3n l\u00fd chuy\u00ean bi\u1ec7t c\u00f9ng \u0111\u1ed9i ng\u0169 k\u1ef9 thu\u1eadt c\u00f3 kinh nghi\u1ec7m \u0111\u1ec3 v\u1eadn h\u00e0nh hi\u1ec7u qu\u1ea3.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Mot-so-thuat-toan-thay-the-Cache-pho-bien-Cache-Replacement-Policies\"><\/span>M\u1ed9t s\u1ed1 thu\u1eadt to\u00e1n thay th\u1ebf Cache ph\u1ed5 bi\u1ebfn (Cache Replacement Policies)<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Khi dung l\u01b0\u1ee3ng Cache b\u1ecb \u0111\u1ea7y (Capacity Miss), h\u1ec7 th\u1ed1ng c\u1ea7n m\u1ed9t &#8220;ng\u01b0\u1eddi g\u00e1c c\u1ed5ng&#8221; th\u00f4ng minh \u0111\u1ec3 quy\u1ebft \u0111\u1ecbnh xem n\u00ean \u0111\u00e1 ai ra \u0111\u1ec3 nh\u01b0\u1eddng ch\u1ed7 cho ng\u01b0\u1eddi m\u1edbi. C\u00e1c thu\u1eadt to\u00e1n n\u00e0y quy\u1ebft \u0111\u1ecbnh tr\u1ef1c ti\u1ebfp \u0111\u1ebfn t\u1ef7 l\u1ec7 Cache Hit c\u1ee7a b\u1ea1n.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"1-LRU-Least-Recently-Used-%E2%80%93-It-duoc-su-dung-gan-day-nhat\"><\/span>1. LRU (Least Recently Used) &#8211; \u00cdt \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng g\u1ea7n \u0111\u00e2y nh\u1ea5t<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0110\u00e2y l\u00e0 thu\u1eadt to\u00e1n ph\u1ed5 bi\u1ebfn v\u00e0 hi\u1ec7u qu\u1ea3 nh\u1ea5t trong h\u1ea7u h\u1ebft c\u00e1c tr\u01b0\u1eddng h\u1ee3p th\u1ef1c t\u1ebf (Redis m\u1eb7c \u0111\u1ecbnh d\u00f9ng bi\u1ebfn th\u1ec3 c\u1ee7a c\u00e1i n\u00e0y). Nguy\u00ean t\u1eafc: &#8220;N\u1ebfu m\u1ed9t d\u1eef li\u1ec7u l\u00e2u r\u1ed3i kh\u00f4ng ai s\u1edd \u0111\u1ebfn, kh\u1ea3 n\u0103ng cao l\u00e0 trong t\u01b0\u01a1ng lai g\u1ea7n c\u0169ng kh\u00f4ng ai c\u1ea7n n\u00f3.&#8221; H\u1ec7 th\u1ed1ng s\u1ebd x\u00f3a nh\u1eefng d\u1eef li\u1ec7u c\u00f3 th\u1eddi gian truy c\u1eadp xa nh\u1ea5t trong qu\u00e1 kh\u1ee9.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"2-FIFO-First-In-First-Out-%E2%80%93-Vao-truoc-ra-truoc\"><\/span>2. FIFO (First In First Out) &#8211; V\u00e0o tr\u01b0\u1edbc ra tr\u01b0\u1edbc<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Nguy\u00ean t\u1eafc: &#8220;Ai v\u00e0o s\u1edbm th\u00ec ph\u1ea3i ra s\u1edbm.&#8221; Thu\u1eadt to\u00e1n n\u00e0y ho\u1ea1t \u0111\u1ed9ng nh\u01b0 m\u1ed9t h\u00e0ng \u0111\u1ee3i (Queue). D\u1eef li\u1ec7u \u0111\u01b0\u1ee3c n\u1ea1p v\u00e0o cache \u0111\u1ea7u ti\u00ean s\u1ebd b\u1ecb x\u00f3a \u0111\u1ea7u ti\u00ean khi cache \u0111\u1ea7y, b\u1ea5t k\u1ec3 d\u1eef li\u1ec7u \u0111\u00f3 c\u00f3 \u0111ang \u0111\u01b0\u1ee3c truy c\u1eadp nhi\u1ec1u hay kh\u00f4ng.<\/p>\n<p>Nh\u01b0\u1ee3c \u0111i\u1ec3m: R\u1ea5t k\u00e9m hi\u1ec7u qu\u1ea3 n\u1ebfu d\u1eef li\u1ec7u c\u0169 (nh\u01b0 trang ch\u1ee7) l\u1ea1i l\u00e0 d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c truy c\u1eadp th\u01b0\u1eddng xuy\u00ean nh\u1ea5t.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"3-LFU-Least-Frequently-Used-%E2%80%93-It-duoc-su-dung-thuong-xuyen-nhat\"><\/span>3. LFU (Least Frequently Used) &#8211; \u00cdt \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng th\u01b0\u1eddng xuy\u00ean nh\u1ea5t<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Nguy\u00ean t\u1eafc: &#8220;Ai \u00edt \u0111\u01b0\u1ee3c d\u00f9ng th\u00ec m\u1eddi ra ngo\u00e0i.&#8221; H\u1ec7 th\u1ed1ng s\u1ebd \u0111\u1ebfm s\u1ed1 l\u1ea7n truy c\u1eadp c\u1ee7a t\u1eebng block d\u1eef li\u1ec7u. Block n\u00e0o c\u00f3 s\u1ed1 l\u1ea7n truy c\u1eadp (counter) th\u1ea5p nh\u1ea5t s\u1ebd b\u1ecb x\u00f3a. Thu\u1eadt to\u00e1n n\u00e0y r\u1ea5t t\u1ed1t \u0111\u1ec3 gi\u1eef l\u1ea1i c\u00e1c d\u1eef li\u1ec7u &#8220;kinh \u0111i\u1ec3n&#8221; \u0111\u01b0\u1ee3c d\u00f9ng nhi\u1ec1u, nh\u01b0ng l\u1ea1i t\u1ed1n t\u00e0i nguy\u00ean \u0111\u1ec3 duy tr\u00ec b\u1ed9 \u0111\u1ebfm (counter) cho t\u1eebng d\u1eef li\u1ec7u.<\/p>\n<p>Khi t\u00ecm hi\u1ec3u <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong>, vi\u1ec7c bi\u1ebft th\u00eam v\u1ec1 LRU hay LFU s\u1ebd gi\u00fap b\u1ea1n c\u1ea5u h\u00ecnh c\u00e1c h\u1ec7 th\u1ed1ng nh\u01b0 Redis, Memcached chu\u1ea9n x\u00e1c h\u01a1n.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Ket-luan\"><\/span>K\u1ebft lu\u1eadn<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>H\u00e0nh tr\u00ecnh t\u00ecm hi\u1ec3u <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong> \u0111\u01b0a ch\u00fang ta \u0111i t\u1eeb nh\u1eefng kh\u00e1i ni\u1ec7m ph\u1ea7n c\u1ee9ng tr\u1eebu t\u01b0\u1ee3ng \u0111\u1ebfn c\u00e1c chi\u1ebfn l\u01b0\u1ee3c t\u1ed1i \u01b0u \u1ee9ng d\u1ee5ng th\u1ef1c t\u1ebf.<\/p>\n<p>Hi\u1ec3u r\u00f5 c\u01a1 ch\u1ebf ho\u1ea1t \u0111\u1ed9ng c\u1ee7a Cache Hit (t\u00ecm th\u1ea5y d\u1eef li\u1ec7u) v\u00e0 Cache Miss (kh\u00f4ng t\u00ecm th\u1ea5y) l\u00e0 n\u1ec1n t\u1ea3ng b\u1eaft bu\u1ed9c cho b\u1ea5t k\u1ef3 ai mu\u1ed1n theo \u0111u\u1ed5i con \u0111\u01b0\u1eddng l\u1eadp tr\u00ecnh chuy\u00ean nghi\u1ec7p hay qu\u1ea3n tr\u1ecb h\u1ec7 th\u1ed1ng (System Admin\/DevOps). M\u1ed9t t\u1ef7 l\u1ec7 Cache Hit cao \u0111\u1ed3ng ngh\u0129a v\u1edbi tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng m\u01b0\u1ee3t m\u00e0, chi ph\u00ed h\u1ea1 t\u1ea7ng th\u1ea5p v\u00e0 kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng h\u1ec7 th\u1ed1ng t\u1ed1t h\u01a1n.<\/p>\n<p>Tuy nhi\u00ean, \u0111\u1eebng qu\u00ean r\u1eb1ng Cache l\u00e0 m\u1ed9t con dao hai l\u01b0\u1ee1i. Vi\u1ec7c l\u1ea1m d\u1ee5ng cache m\u00e0 kh\u00f4ng hi\u1ec3u v\u1ec1 c\u00e1c thu\u1eadt to\u00e1n thay th\u1ebf hay v\u1ea5n \u0111\u1ec1 \u0111\u1ed3ng b\u1ed9 d\u1eef li\u1ec7u c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn vi\u1ec7c hi\u1ec3n th\u1ecb th\u00f4ng tin sai l\u1ec7ch cho ng\u01b0\u1eddi d\u00f9ng. H\u00e3y lu\u00f4n c\u00e2n b\u1eb1ng gi\u1eefa dung l\u01b0\u1ee3ng b\u1ed9 nh\u1edb, thu\u1eadt to\u00e1n t\u1ed1i \u01b0u v\u00e0 c\u1ea5u tr\u00fac h\u1ec7 th\u1ed1ng.<\/p>\n<p>Hy v\u1ecdng b\u00e0i vi\u1ebft n\u00e0y c\u1ee7a InterData \u0111\u00e3 gi\u00fap b\u1ea1n gi\u1ea3i t\u1ecfa m\u1ecdi th\u1eafc m\u1eafc xoay quanh ch\u1ee7 \u0111\u1ec1 <strong>Cache Hit v\u00e0 Cache Miss l\u00e0 g\u00ec<\/strong>. H\u00e3y \u00e1p d\u1ee5ng ngay nh\u1eefng ki\u1ebfn th\u1ee9c n\u00e0y v\u00e0o d\u1ef1 \u00e1n c\u1ee7a b\u1ea1n \u0111\u1ec3 c\u1ea3m nh\u1eadn s\u1ef1 kh\u00e1c bi\u1ec7t v\u1ec1 hi\u1ec7u n\u0103ng!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Khi website ho\u1eb7c h\u1ec7 th\u1ed1ng x\u1eed l\u00fd d\u1eef li\u1ec7u ng\u00e0y c\u00e0ng l\u1edbn, t\u1ed1c \u0111\u1ed9 ph\u1ea3n h\u1ed3i tr\u1edf th\u00e0nh y\u1ebfu t\u1ed1 then ch\u1ed1t \u1ea3nh h\u01b0\u1edfng tr\u1ef1c ti\u1ebfp \u0111\u1ebfn tr\u1ea3i nghi\u1ec7m ng\u01b0\u1eddi d\u00f9ng v\u00e0 hi\u1ec7u su\u1ea5t v\u1eadn h\u00e0nh. M\u1ed9t trong nh\u1eefng k\u1ef9 thu\u1eadt quan tr\u1ecdng gi\u00fap t\u0103ng t\u1ed1c h\u1ec7 th\u1ed1ng ch\u00ednh l\u00e0 cache. Tuy nhi\u00ean, vi\u1ec7c cache<\/p>\n","protected":false},"author":11,"featured_media":37289,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[],"class_list":["post-37282","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server"],"_links":{"self":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/37282","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/comments?post=37282"}],"version-history":[{"count":1,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/37282\/revisions"}],"predecessor-version":[{"id":37290,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/posts\/37282\/revisions\/37290"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media\/37289"}],"wp:attachment":[{"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/media?parent=37282"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/categories?post=37282"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/interdata.vn\/blog\/wp-json\/wp\/v2\/tags?post=37282"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}