Linux下清理内存和Cache方法

频繁的文件访问会导致系统的Cache使用量大增

  $ free -m

  total used free shared buffers cached

  Mem: 3955 3926 28 0 55 3459

  -/+ buffers/cache: 411 3544

  Swap: 5726 0 5726

  free内存减少到几十兆,系统运行缓慢

  运行sync将dirty的内容写回硬盘

  $sync

  通过修改proc系统的drop_caches清理free的cache

  $echo 3 > /proc/sys/vm/drop_caches

  drop_caches的详细文档如下:

  Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.

  To free pagecache:

  * echo 1 > /proc/sys/vm/drop_caches

  To free dentries and inodes:

  * echo 2 > /proc/sys/vm/drop_caches

  To free pagecache, dentries and inodes:

  * echo 3 > /proc/sys/vm/drop_caches

  As this is a non-destructive operation, and dirty objects are notfreeable, the user should run "sync" first in order to make sure allcached objects are freed.

  This tunable was added in 2.6.16.

  修改/etc/sysctl.conf 添加如下选项后就不会内存持续增加

  vm.dirty_ratio = 1

  vm.dirty_background_ratio=1

  vm.dirty_writeback_centisecs=2

  vm.dirty_expire_centisecs=3

  vm.drop_caches=3

  vm.swappiness =100

  vm.vfs_cache_pressure=163

  vm.overcommit_memory=2

  vm.lowmem_reserve_ratio=32 32 8

  kern.maxvnodes=3

  上面的设置比较粗暴,使cache的作用基本无法发挥。需要根据机器的状况进行适当的调节寻找最佳的折衷。

  转载自:http://bbs.unixall.com/thread-1012-1-1.html

上一篇: c#中快捷键的设置(esc退出窗体)   下一篇: MHDD图解教程

提交疑问

回顶部