{"id":1975,"date":"2019-08-31T15:23:20","date_gmt":"2019-08-31T08:23:20","guid":{"rendered":"https:\/\/tino.vn\/?post_type=ht_kb&#038;p=1975"},"modified":"2020-02-28T17:05:22","modified_gmt":"2020-02-28T10:05:22","slug":"cach-doc-thong-so-ram-qua-lenh-free","status":"publish","type":"ht_kb","link":"https:\/\/tino.vn\/blog\/docs\/cach-doc-thong-so-ram-qua-lenh-free\/","title":{"rendered":"C\u00e1ch \u0111\u1ecdc th\u00f4ng s\u1ed1 ram qua l\u1ec7nh free"},"content":{"rendered":"<p><iframe loading=\"lazy\" src=\"\/\/www.youtube.com\/embed\/Qerxg_dw3RE\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>\u0110\u1ec3 xem l\u01b0\u1ee3ng RAM \u0111\u00e3 s\u1eed d\u1ee5ng ch\u00fang ta c\u00f3 r\u1ea5t nhi\u1ec1u l\u1ec7nh kh\u00e1c nhau nh\u01b0:<\/p>\n<pre>free -m (T\u00ednh dung l\u01b0\u1ee3ng theo MB)\r\nfree (T\u00ednh dung l\u01b0\u1ee3ng theo KB)<\/pre>\n<pre>cat \/proc\/meminfo<\/pre>\n<pre>top<\/pre>\n<pre>vmstat -s<\/pre>\n<p>Ch\u1eb3ng h\u1ea1n m\u1ed9t v\u00ed d\u1ee5 \u0111\u1ed1i v\u1edbi l\u1ec7nh free:<\/p>\n<pre>free -m\r\n\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0total\u00a0 \u00a0 \u00a0used \u00a0 \u00a0 \u00a0free\u00a0 \u00a0 \u00a0 shared \u00a0 \u00a0 \u00a0buff\/cache \u00a0 \u00a0 \u00a0available\r\nMem: \u00a0 \u00a0       1838\u00a0 \u00a0\u00a0  553 \u00a0 \u00a0  \u00a0494 \u00a0 \u00a0  \u00a0 \u00a0\u00a011 \u00a0 \u00a0  \u00a0 \u00a0789 \u00a0 \u00a0  \u00a0 \u00a0   \u00a01074\r\nSwap: \u00a0 \u00a0     \u00a04095 \u00a0 \u00a0   0 \u00a0 \u00a0  \u00a0 4095<\/pre>\n<ol>\n<li><strong>total<\/strong> Hi\u1ec3n th\u1ecb t\u1ed5ng dung l\u01b0\u1ee3ng RAM c\u00f3 .<\/li>\n<li><strong>used<\/strong> Hi\u1ec3n th\u1ecb RAM \u0111\u00e3 s\u1eed d\u1ee5ng.<\/li>\n<li><strong>free<\/strong> Hi\u1ec3n th\u1ecb ram c\u00f2n tr\u1ed1ng.<\/li>\n<li><strong>shared<\/strong> hi\u1ec3n th\u1ecb ram s\u1eed d\u1ee5ng d\u00e0nh cho d\u1ecbch v\u1ee5 ramdisk<\/li>\n<li><strong>buffers<\/strong> hi\u1ec3n th\u1ecb ram s\u1eed d\u1ee5ng b\u1edfi<strong> kernel buffers<\/strong>.<\/li>\n<li><strong>cached<\/strong> Ram s\u1eed d\u1ee5ng b\u1edfi page cache v\u00e0 slabs(Cached and Slab available in \/proc\/meminfo).<\/li>\n<li><strong>buffers\/cache<\/strong>\u00a0 hi\u1ec3n th\u1ecb t\u1ed5ng dung l\u01b0\u1ee3ng buffers v\u00e0 cache.<\/li>\n<\/ol>\n<pre>Th\u1ef1c t\u1ebf th\u00ec: Total = used + free + buff\/cache.<\/pre>\n<p>Tuy nhi\u00ean, th\u00f4ng s\u1ed1\u00a0MemFree tr\u1ea3 v\u1ec1 kh\u00f4ng ph\u1ea3i l\u00e0 l\u01b0\u1ee3ng b\u1ed9 nh\u1edb h\u1ec7 th\u1ed1ng c\u00f2n tr\u1ed1ng.<\/p>\n<p>B\u1edfi v\u00ec Total memory \u1edf Linux \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng Active memory + Inactive memory (kh\u00f4ng t\u00ednh\u00a0Swap). V\u1ea5n \u0111\u1ec1 \u1edf ch\u1ed7 Inactive memory,\u00a0l\u00e0 v\u00f9ng nh\u1edb khi ta run 1 process v\u00e0 t\u1eaft \u0111i, system s\u1ebd cache l\u1ea1i v\u00f9ng nh\u1edb n\u00e0y \u0111\u1ec3 khi g\u1ecdi l\u1ea1i process n\u00e0y l\u1ea7n n\u1eefa, n\u00f3 s\u1ebd s\u1eed d\u1ee5ng v\u00f9ng nh\u1edb inactive\u00a0n\u00e0y ngay l\u1eadp t\u1ee9c thay v\u00ec ph\u1ea3i c\u1ea5p ph\u00e1t l\u1ea1i. N\u00ean khi ta m\u1edf c\u00e0ng nhi\u1ec1u process, sau \u0111\u00f3 t\u1eaft \u0111i, inactive memory c\u00e0ng chi\u1ebfm nhi\u1ec1u(k\u1ef9 thu\u1eadt Disk Caching c\u1ee7a Linux)<\/p>\n<p>Khi m\u1edf l\u00ean 1 process m\u1edbi, n\u1ebfu h\u1ec7 th\u1ed1ng thi\u1ebfu RAM th\u00ec Linux s\u1ebd t\u1ef1 \u0111\u1ed9ng chuy\u1ec3n v\u00f9ng b\u1ed9 nh\u1edb Inactive v\u00e0o Swap v\u00e0 d\u00e0nh to\u00e0n b\u1ed9 memory cho active process. Nh\u01b0 v\u1eady, h\u1ec7 th\u1ed1ng kh\u00f4ng b\u1ecb qu\u00e1 t\u1ea3i.<\/p>\n<p>K\u1ebft lu\u1eadn, d\u1ea5u hi\u1ec7u \u0111\u1ec3 nh\u1eadn bi\u1ebft h\u1ec7 th\u1ed1ng c\u00f3 \u0111ang thi\u1ebfu RAM hay kh\u00f4ng \u0111\u00f3 l\u00e0 b\u1ea1n h\u00e3y nh\u00ecn v\u00e0o Swap, n\u1ebfu Swap s\u1eed d\u1ee5ng nhi\u1ec1u ch\u1ee9ng t\u1ecf \u0111ang b\u1ecb thi\u1ebfu RAM, l\u00fac n\u00e0y c\u1ea7n n\u00e2ng c\u1ea5p b\u1ed9 nh\u1edb cho VPS\/Server.<\/p>\n<p>Trong tr\u01b0\u1eddng h\u1ee3p kh\u00f4ng c\u00f3 swap, c\u00e1c b\u1ea1n h\u00e3y s\u1eed d\u1ee5ng l\u1ec7nh\u00a0<code>free -h<\/code>\u00a0v\u00e0 nh\u00ecn v\u00e0o d\u00f2ng<code>-\/+ buffers\/cache<\/code>\u00a0\u0111\u1ec3 xem h\u1ec7 th\u1ed1ng \u0111ang th\u1ef1c s\u1ef1 free bao nhi\u00eau memory.<\/p>\n<p><strong>\u0110\u1ed1i v\u1edbi CentOS 6<\/strong><\/p>\n<p><a href=\"https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h.png\" data-featherlight=\"image\"><img decoding=\"async\" class=\"aligncenter wp-image-2310 size-full\" src=\"https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h.png\" sizes=\"(max-width: 1040px) 100vw, 1040px\" srcset=\"https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h.png 1040w, https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/1_Cent6-free-h-300x35.png 300w, https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/1_Cent6-free-h-768x91.png 768w, https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h-665x79.png 665w, https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h-60x7.png 60w, https:\/\/tino.vn\/blog\/wp-content\/uploads\/2019\/08\/Cent6-free-h-150x18.png 150w\" alt=\"\" width=\"1040\" height=\"123\" title=\"\"><\/a><br \/>\nH\u1ec7 th\u1ed1ng c\u00f3 t\u1ed5ng c\u1ed9ng 996MB RAM, m\u1edbi d\u00f9ng 193MB (19.37%) v\u00e0 c\u00f2n tr\u1ed1ng 802MB. Swap 2GB ch\u01b0a \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ebfn.<\/p>\n<p><strong>\u0110\u1ed1i v\u1edbi CentOS 7<\/strong><\/p>\n<p><a href=\"https:\/\/www.screencast.com\/t\/t18vTHaQblTP\" rel=\"nofollow noopener\" target=\"_blank\"><img decoding=\"async\" src=\"https:\/\/content.screencast.com\/users\/JohnGrayWorld\/folders\/Snagit\/media\/a9580432-7be7-45cc-bc6c-dd7c01a7f0ed\/08.31.2019-15.22.png?source=oembed\" alt=\"08.31.2019-15.22.01\" width=\"500\" height=\"80\" title=\"\"><\/a><br \/>\nH\u1ec7 th\u1ed1ng c\u00f3 t\u1ed5ng c\u1ed9ng 488MB RAM, s\u1eed d\u1ee5ng th\u1ef1c t\u1ebf ch\u1ec9 125MB. C\u00f2n tr\u1ed1ng 6MB v\u00e0 357MB (s\u1eed d\u1ee5ng l\u00e0m buff\/cache). Swap 1GB ch\u01b0a \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ebfn. \u0110i\u1ec1u b\u1ea1n c\u1ea7n quan t\u00e2m l\u00e0 l\u01b0\u1ee3ng RAM tr\u1ed1ng th\u1ef1c t\u1ebfm\u00e0 c\u00e1c \u1ee9ng d\u1ee5ng c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng (available) \u2013 286MB<\/p>\n<p>Nh\u01b0 v\u1eady, t\u00edn hi\u1ec7u \u0111\u1ec3 b\u1ea1n lo l\u1eafng l\u00e0 khi:<\/p>\n<ul>\n<li>Available memory ho\u1eb7c free c\u1ee7a -\/+ buffers\/cache ti\u1ebfn \u0111\u1ebfn 0<\/li>\n<li>M\u1ee9c s\u1eed d\u1ee5ng swap gia t\u0103ng<\/li>\n<\/ul>\n<p>\u0110\u1ed1i v\u1edbi tr\u01b0\u1eddng h\u1ee3p x\u1ea3y ra khi c\u00f3 d\u1ea5u hi\u1ec7u d\u00f9ng qu\u00e1 nhi\u1ec1u ram, b\u1ea1n n\u00ean ki\u1ec3m tra l\u1ea1i d\u1ecbch v\u1ee5 ho\u1eb7c c\u00f3 k\u1ebf ho\u1ea1ch n\u00e2ng c\u1ea5p Ram \u0111\u1ed1i v\u1edbi VPS c\u1ee7a m\u00ecnh. V\u1edbi c\u00e1c h\u1ec7 \u0111i\u1ec1u h\u00e0nh linux, m\u1ee9c \u0111\u1ed9 ra khuy\u00ean d\u00f9ng v\u1edbi b\u1ea5t k\u1ef3 m\u1ed9t VPS \u0111\u1ec3 ch\u1ea1y c\u00e1c d\u1ecbch v\u1ee5 website n\u00ean t\u1ed1i thi\u1ec3u l\u00e0 2GB.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u0110\u1ec3 xem l\u01b0\u1ee3ng RAM \u0111\u00e3 s\u1eed d\u1ee5ng ch\u00fang ta c\u00f3 r\u1ea5t nhi\u1ec1u l\u1ec7nh kh\u00e1c nhau nh\u01b0: free -m (T\u00ednh dung l\u01b0\u1ee3ng theo MB) free (T\u00ednh dung l\u01b0\u1ee3ng theo KB) cat \/proc\/meminfo top vmstat -s Ch\u1eb3ng h\u1ea1n m\u1ed9t v\u00ed d\u1ee5 \u0111\u1ed1i v\u1edbi l\u1ec7nh free: free -m \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0total\u00a0 \u00a0 \u00a0used [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":1977,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","format":"standard","meta":{"footnotes":""},"tags":[],"ht_kb_category":[17],"class_list":["post-1975","ht_kb","type-ht_kb","status-publish","format-standard","has-post-thumbnail","hentry","ht_kb_category-huong-dan-ve-cloud-vps"],"_links":{"self":[{"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/ht_kb\/1975","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/ht_kb"}],"about":[{"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/types\/ht_kb"}],"author":[{"embeddable":true,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/comments?post=1975"}],"version-history":[{"count":0,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/ht_kb\/1975\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/media\/1977"}],"wp:attachment":[{"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/media?parent=1975"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/tags?post=1975"},{"taxonomy":"ht_kb_category","embeddable":true,"href":"https:\/\/tino.vn\/blog\/wp-json\/wp\/v2\/ht_kb_category?post=1975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}