我知道 Linux 使用未使用的 RAM 来缓存某些文件。但我想知道它实际上缓存了哪些文件!如果你看一下free
:
Gesamt Belegt Frei Gemeinsam Puffer Cached
Speicher: 5,8G 3,7G 2,1G 0B 259M 1,7G
-/+ Puffer/Cache: 1,8G 4,0G
Auslagerungsdatei: 4,0G 0B 4,0G
它说我的 RAM 中有 1.7 GB 被用作缓存。我知道这不是有害行为,但我很好奇 Linux 认为哪些文件值得缓存。是否有命令/文件可以显示缓存的文件?
答案1
如果我没记错的话,Linux 内核缓存具体页面文件的缓存,即不是整个文件都加载到页面缓存中。您可以使用一个工具来确定一些文件的内容在页面缓存中fincore
来自linux-ftools
项目。虽然它不会显示磁盘上的所有缓存文件,但它可以让您大致了解加载到页面缓存中的内容。
一个例子(引自该项目的网站):
root@xxxxxx:/var/lib/mysql/blogindex# fincore --pages=false --summarize --only-cached *
stats for CLUSTER_LOG_2010_05_21.MYI: file size=93840384 , total pages=22910 , cached pages=1 , cached size=4096, cached perc=0.004365
stats for CLUSTER_LOG_2010_05_22.MYI: file size=417792 , total pages=102 , cached pages=1 , cached size=4096, cached perc=0.980392
stats for CLUSTER_LOG_2010_05_23.MYI: file size=826368 , total pages=201 , cached pages=1 , cached size=4096, cached perc=0.497512
stats for CLUSTER_LOG_2010_05_24.MYI: file size=192512 , total pages=47 , cached pages=1 , cached size=4096, cached perc=2.127660
stats for CLUSTER_LOG_2010_06_03.MYI: file size=345088 , total pages=84 , cached pages=43 , cached size=176128, cached perc=51.190476
stats for CLUSTER_LOG_2010_06_04.MYD: file size=1478552 , total pages=360 , cached pages=97 , cached size=397312, cached perc=26.944444
stats for CLUSTER_LOG_2010_06_04.MYI: file size=205824 , total pages=50 , cached pages=29 , cached size=118784, cached perc=58.000000
stats for COMMENT_CONTENT_2010_06_03.MYI: file size=100051968 , total pages=24426 , cached pages=10253 , cached size=41996288, cached perc=41.975764
stats for COMMENT_CONTENT_2010_06_04.MYD: file size=716369644 , total pages=174894 , cached pages=79821 , cached size=326946816, cached perc=45.639645
stats for COMMENT_CONTENT_2010_06_04.MYI: file size=56832000 , total pages=13875 , cached pages=5365 , cached size=21975040, cached perc=38.666667
stats for FEED_CONTENT_2010_06_03.MYI: file size=1001518080 , total pages=244511 , cached pages=98975 , cached size=405401600, cached perc=40.478751
stats for FEED_CONTENT_2010_06_04.MYD: file size=9206385684 , total pages=2247652 , cached pages=1018661 , cached size=4172435456, cached perc=45.321117
stats for FEED_CONTENT_2010_06_04.MYI: file size=638005248 , total pages=155763 , cached pages=52912 , cached size=216727552, cached perc=33.969556
stats for FEED_CONTENT_2010_06_04.frm: file size=9840 , total pages=2 , cached pages=3 , cached size=12288, cached perc=150.000000
stats for PERMALINK_CONTENT_2010_06_03.MYI: file size=1035290624 , total pages=252756 , cached pages=108563 , cached size=444674048, cached perc=42.951700
stats for PERMALINK_CONTENT_2010_06_04.MYD: file size=55619712720 , total pages=13579031 , cached pages=6590322 , cached size=26993958912, cached perc=48.533080
stats for PERMALINK_CONTENT_2010_06_04.MYI: file size=659397632 , total pages=160985 , cached pages=54304 , cached size=222429184, cached perc=33.732335
stats for PERMALINK_CONTENT_2010_06_04.frm: file size=10156 , total pages=2 , cached pages=3 , cached size=12288, cached perc=150.000000
---
total cached size: 32847278080
上面的命令列出了一些在页面缓存中存储了一些页面的*.MYD、*.MYI 和*.frm 文件。
如果你确实想找出页面缓存中至少有 1 页的所有文件,这可能会有效(未经测试,会产生大量输出并且可能需要很长时间才能运行):
cd /
find . -type f | xargs fincore --pages=false --summarize --only-cached