給大家介紹個好玩的工具--vmtouch，可以查看某個文件在內存的使用。下面是摘錄其網站，有興趣的童鞋可以自己研究下

下載源碼wget?http://hoytech.com/vmtouch/vmtouch.c

編譯gcc -Wall -O3 -o vmtouch vmtouch.c

cp vmtouch /usr/local/bin/

Example 1

How much of the /bin/ directory is currently in cache?

$ vmtouch /bin/ Files: 92 Directories: 1 Resident Pages: 348/1307 1M/5M 26.6% Elapsed: 0.003426 seconds

Example 2

How much of?big-dataset.txt?is currently in memory?

$ vmtouch -v big-dataset.txt big-dataset.txt [ ] 0/42116 Files: 1 Directories: 0 Resident Pages: 0/42116 0/164M 0% Elapsed: 0.005182 seconds None of it. Now let's bring part of it into memory with?tail: $ tail -n 10000 big-dataset.txt > /dev/null Now how much? $ vmtouch -v big-dataset.txt big-dataset.txt [ oOOOOOOO] 4950/42116 Files: 1 Directories: 0 Resident Pages: 4950/42116 19M/164M 11.8% Elapsed: 0.006706 seconds?vmtouch?tells us that 4950 pages at the end of the file are now resident in memory.

Example 3

Let's bring the rest of?big-dataset.txt?into memory (pressing enter a few times to illustrate the animated progress bar you will see on your terminal):

$ vmtouch -vt big-dataset.txt big-dataset.txt [OOo oOOOOOOO] 6887/42116 [OOOOOOOOo oOOOOOOO] 10631/42116 [OOOOOOOOOOOOOOo oOOOOOOO] 15351/42116 [OOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 19719/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 24183/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 28615/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 31415/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 36775/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOo oOOOOOOO] 39431/42116 [OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO] 42116/42116 Files: 1 Directories: 0 Touched Pages: 42116 (164M) Elapsed: 12.107 seconds

Example 4

We have 3 big datasets,?a.txt,?b.txt, and?c.txt?but only 2 of them will fit in memory at once. If we have?a.txt?and?b.txt?in memory but would now like to work withb.txt?and?c.txt, we could just start loading up?c.txt?but then our system would evict pages from both?a.txt?(which we want) and?b.txt?(which we don't want).

So let's give the system a hint and?evict?a.txt?from memory, making room for?c.txt:

$ vmtouch -ve a.txt Evicting a.txt Files: 1 Directories: 0 Evicted Pages: 42116 (164M) Elapsed: 0.076824 seconds

Example 5

Daemonise?and?lock?all files in a directory into physical memory:

vmtouch -dl /var/www/htdocs/critical/

本文轉自 taojin1240 51CTO博客，原文鏈接：http://blog.51cto.com/taotao1240/743249，如需轉載請自行聯系原作者

總結

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