\u5f53\u5728Linux\u4e0b\u9891\u7e41\u5b58\u53d6\u6587\u4ef6\u540e\uff0c\u7269\u7406\u5185\u5b58\u4f1a\u5f88\u5feb\u88ab\u7528\u5149\uff0c\u5f53\u7a0b\u5e8f\u7ed3\u675f\u540e\uff0c\u5185\u5b58\u4e0d\u4f1a\u88ab\u6b63\u5e38\u91ca\u653e\uff0c\u800c\u662f\u4e00\u76f4\u4f5c\u4e3acaching\u3002\u8fd9\u4e2a\u95ee\u9898\uff0c\u8c8c\u4f3c\u6709\u4e0d\u5c11\u4eba\u5728\u95ee\uff0c\u4e0d\u8fc7\u90fd\u6ca1\u6709\u770b\u5230\u6709\u4ec0\u4e48\u5f88\u597d\u89e3\u51b3\u7684\u529e\u6cd5\u3002\u90a3\u4e48<\/p>\n
\u6211\u6765\u8c08\u8c08\u8fd9\u4e2a\u95ee\u9898\u3002<\/p>\n
\u4e00\u3001\u901a\u5e38\u60c5\u51b5<\/p>\n
\u5148\u6765\u8bf4\u8bf4free\u547d\u4ee4\uff1a<\/p>\n
[root@server ]# free -m<\/p>\n
total used free shared buffers cached<\/p>\n
Mem: 249 163 86 0 10 94<\/p>\n
-\/+ buffers\/cache: 58 191<\/p>\n
Swap: 511 0 511<\/p>\n
\u5176\u4e2d\uff1a<\/p>\n
total \u5185\u5b58\u603b\u6570<\/p>\n
used \u5df2\u7ecf\u4f7f\u7528\u7684\u5185\u5b58\u6570<\/p>\n
free \u7a7a\u95f2\u7684\u5185\u5b58\u6570<\/p>\n
shared \u591a\u4e2a\u8fdb\u7a0b\u5171\u4eab\u7684\u5185\u5b58\u603b\u989d<\/p>\n
buffers Buffer Cache\u548ccached Page Cache \u78c1\u76d8\u7f13\u5b58\u7684\u5927\u5c0f<\/p>\n
-buffers\/cache \u7684\u5185\u5b58\u6570:used \u2013 buffers \u2013 cached<\/p>\n
+buffers\/cache \u7684\u5185\u5b58\u6570:free + buffers + cached<\/p>\n
\u53ef\u7528\u7684memory=free memory+buffers+cached\u3002<\/p>\n
\u6709\u4e86\u8fd9\u4e2a\u57fa\u7840\u540e\uff0c\u53ef\u4ee5\u5f97\u77e5\uff0c\u6211\u73b0\u5728used\u4e3a163MB\uff0cfree\u4e3a86MB\uff0cbuffer\u548ccached\u5206\u522b\u4e3a10MB\uff0c94MB\u3002<\/p>\n
\u90a3\u4e48\u6211\u4eec\u6765\u770b\u770b,\u5982\u679c\u6211\u6267\u884c\u590d\u5236\u6587\u4ef6,\u5185\u5b58\u4f1a\u53d1\u751f\u4ec0\u4e48\u53d8\u5316.<\/p>\n
[root@server ]# cp -r \/etc ~\/test\/<\/p>\n
[root@server ]# free -m<\/p>\n
total used free shared buffers cached<\/p>\n
Mem: 249 244 4 0 8 174<\/p>\n
-\/+ buffers\/cache: 62 187<\/p>\n
Swap: 511 0 511<\/p>\n
\u5728\u6211\u547d\u4ee4\u6267\u884c\u7ed3\u675f\u540e\uff0cused\u4e3a244MB\uff0cfree\u4e3a4MB\uff0cbuffers\u4e3a8MB\uff0ccached\u4e3a174MB\uff0c\u5929\u5450\uff0c\u90fd\u88abcached\u5403\u6389\u4e86\u3002\u522b\u7d27\u5f20\uff0c\u8fd9\u662f\u4e3a\u4e86\u63d0\u9ad8\u6587\u4ef6\u8bfb\u53d6\u6548\u7387\u7684\u505a\u6cd5\u3002<\/p>\n
\u4e3a\u4e86\u63d0\u9ad8\u78c1\u76d8\u5b58\u53d6\u6548\u7387\uff0cLinux\u505a\u4e86\u4e00\u4e9b\u7cbe\u5fc3\u7684\u8bbe\u8ba1\uff0c\u9664\u4e86\u5bf9dentry\u8fdb\u884c\u7f13\u5b58\uff08\u7528\u4e8eVFS\uff0c\u52a0\u901f\u6587\u4ef6\u8def\u5f84\u540d\u5230inode\u7684\u8f6c\u6362\uff09\uff0c\u8fd8\u91c7\u53d6\u4e86\u4e24\u79cd\u4e3b\u8981Cache\u65b9\u5f0f\uff1aBuffer Cache\u548cPage Cache\u3002\u524d\u8005\u9488\u5bf9\u78c1<\/p>\n
\u76d8\u5757\u7684\u8bfb\u5199\uff0c\u540e\u8005\u9488\u5bf9\u6587\u4ef6inode\u7684\u8bfb\u5199\u3002\u8fd9\u4e9bCache\u6709\u6548\u7f29\u77ed\u4e86 I\/O\u7cfb\u7edf\u8c03\u7528\uff08\u6bd4\u5982read\uff0cwrite\uff0cgetdents\uff09\u7684\u65f6\u95f4\u3002<\/p>\n
\u90a3\u4e48\u6709\u4eba\u8bf4\u8fc7\u6bb5\u65f6\u95f4\uff0clinux\u4f1a\u81ea\u52a8\u91ca\u653e\u6389\u6240\u7528\u7684\u5185\u5b58\u3002\u7b49\u5f85\u4e00\u6bb5\u65f6\u95f4\u540e\uff0c\u6211\u4eec\u4f7f\u7528free\u518d\u6765\u8bd5\u8bd5\uff0c\u770b\u770b\u662f\u5426\u6709\u91ca\u653e\uff1f<\/p>\n
[root@server]# free -m<\/p>\n
total used free shared buffers cached<\/p>\n
Mem: 249 244 5 0 8 174<\/p>\n
-\/+ buffers\/cache: 61 188<\/p>\n
Swap: 511 0 511<\/p>\n
\u4f3c\u4e4e\u6ca1\u6709\u4efb\u4f55\u53d8\u5316\u3002\uff08\u5b9e\u9645\u60c5\u51b5\u4e0b\uff0c\u5185\u5b58\u7684\u7ba1\u7406\u8fd8\u4e0eSwap\u6709\u5173\uff09<\/p>\n
\u90a3\u4e48\u6211\u80fd\u5426\u624b\u52a8\u91ca\u653e\u6389\u8fd9\u4e9b\u5185\u5b58\u5462\uff1f\u56de\u7b54\u662f\u53ef\u4ee5\u7684\uff01<\/p>\n
\u4e8c\u3001\u624b\u52a8\u91ca\u653e\u7f13\u5b58<\/p>\n
\/proc\u662f\u4e00\u4e2a\u865a\u62df\u6587\u4ef6\u7cfb\u7edf\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u5bf9\u5b83\u7684\u8bfb\u5199\u64cd\u4f5c\u505a\u4e3a\u4e0ekernel\u5b9e\u4f53\u95f4\u8fdb\u884c\u901a\u4fe1\u7684\u4e00\u79cd\u624b\u6bb5\u3002\u4e5f\u5c31\u662f\u8bf4\u53ef\u4ee5\u901a\u8fc7\u4fee\u6539\/proc\u4e2d\u7684\u6587\u4ef6\uff0c\u6765\u5bf9\u5f53\u524dkernel\u7684\u884c\u4e3a\u505a\u51fa\u8c03\u6574\u3002\u90a3\u4e48\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u8c03<\/p>\n
\u6574\/proc\/sys\/vm\/drop_caches\u6765\u91ca\u653e\u5185\u5b58\u3002\u64cd\u4f5c\u5982\u4e0b\uff1a<\/p>\n
[root@server]# cat \/proc\/sys\/vm\/drop_caches<\/p>\n
0<\/p>\n
\u9996\u5148\uff0c\/proc\/sys\/vm\/drop_caches\u7684\u503c\uff0c\u9ed8\u8ba4\u4e3a0\u3002<\/p>\n
[root@server]# sync<\/p>\n
\u624b\u52a8\u6267\u884csync\u547d\u4ee4
\n\/\/ \u63cf\u8ff0\uff1async \u547d\u4ee4\u8fd0\u884c sync \u5b50\u4f8b\u7a0b\u3002\u5982\u679c\u5fc5\u987b\u505c\u6b62\u7cfb\u7edf\uff0c\u5219\u8fd0\u884csync \u547d\u4ee4\u4ee5\u786e\u4fdd\u6587\u4ef6\u7cfb\u7edf\u7684\u5b8c\u6574\u6027\u3002sync \u547d\u4ee4\u5c06\u6240\u6709\u672a\u5199\u7684\u7cfb\u7edf\u7f13\u51b2\u533a\u5199\u5230\u78c1\u76d8\u4e2d\uff0c\u5305\u542b\u5df2\u4fee\u6539\u7684 i-node\u3001\u5df2\u5ef6\u8fdf\u7684\u5757 I\/O \u548c\u8bfb\u5199\u6620\u5c04\u6587\u4ef6,\u5426\u5219\u5728\u91ca\u653e\u7f13\u5b58\u7684\u8fc7\u7a0b\u4e2d\uff0c\u53ef\u80fd\u4f1a\u4e22\u5931\u672a\u4fdd\u5b58\u7684\u6587\u4ef6<\/p>\n
[root@server]# echo 3 > \/proc\/sys\/vm\/drop_caches<\/p>\n
[root@server]# cat \/proc\/sys\/vm\/drop_caches<\/p>\n
3<\/p>\n
\u5c06\/proc\/sys\/vm\/drop_caches\u503c\u8bbe\u4e3a3<\/p>\n
[root@server]# free -m<\/p>\n
total used free shared buffers cached<\/p>\n
Mem: 249 66 182 0 0 11<\/p>\n
-\/+ buffers\/cache: 55 194<\/p>\n
Swap: 511 0 511<\/p>\n
\u518d\u6765\u8fd0\u884cfree\u547d\u4ee4\uff0c\u4f1a\u53d1\u73b0\u73b0\u5728\u7684used\u4e3a66MB\uff0cfree\u4e3a182MB\uff0cbuffers\u4e3a0MB\uff0ccached\u4e3a11MB\u3002\u90a3\u4e48\u6709\u6548\u7684\u91ca\u653e\u4e86buffer\u548ccache\u3002<\/p>\n
\u67e5\u770b\u5185\u5b58\u6761\u6570\u547d\u4ee4\uff1a
\ndmidecode | grep -A16 “Memory Device$”<\/p>\n
\u25ce \u6709\u5173\/proc\/sys\/vm\/drop_caches\u7684\u7528\u6cd5\u5728\u4e0b\u9762\u8fdb\u884c\u4e86\u8bf4\u660e<\/p>\n
\/proc\/sys\/vm\/drop_caches (since Linux 2.6.16)<\/p>\n
0 \u2013 \u4e0d\u91ca\u653e
\n1 \u2013 \u91ca\u653e\u9875\u7f13\u5b58
\n2 \u2013 \u91ca\u653edentries\u548cinodes
\n3 \u2013 \u91ca\u653e\u6240\u6709\u7f13\u5b58<\/p>\n
\/\/\u8f6c\u8f7d\u81ea\u7f51\u7edc\u535a\u5ba2,\u5982\u679c\u4fb5\u72af\u60a8\u7684\u6743\u76ca,\u8bf7\u8054\u7cfb\u5c0f\u7f16\u5220\u9664.<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5f53\u5728Linux\u4e0b\u9891\u7e41\u5b58\u53d6\u6587\u4ef6\u540e\uff0c\u7269\u7406\u5185\u5b58\u4f1a\u5f88\u5feb\u88ab\u7528\u5149\uff0c\u5f53\u7a0b\u5e8f\u7ed3\u675f\u540e\uff0c\u5185\u5b58\u4e0d\u4f1a\u88ab\u6b63\u5e38\u91ca\u653e\uff0c\u800c\u662f\u4e00\u76f4\u4f5c\u4e3acachi … \u9605\u8bfb\u66f4\u591a<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[49],"tags":[259,260],"class_list":["post-669","post","type-post","status-publish","format-standard","hentry","category-linux","tag-linux","tag-260"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/669","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/comments?post=669"}],"version-history":[{"count":2,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/669\/revisions"}],"predecessor-version":[{"id":671,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/posts\/669\/revisions\/671"}],"wp:attachment":[{"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/media?parent=669"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/categories?post=669"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cn.hostease.com\/xueyuan\/wp-json\/wp\/v2\/tags?post=669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}