Linux下清理內(nèi)存和Cache方法 /proc/sys/vm/drop_caches
頻繁的文件訪問會(huì)導(dǎo)致系統(tǒng)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內(nèi)存減少到幾十兆辛燥，系統(tǒng)運(yùn)行緩慢
運(yùn)行sync將dirty的內(nèi)容寫回硬盤
$sync
通過修改proc系統(tǒng)的drop_caches清理free的cache
$echo 3 > /proc/sys/vm/drop_caches
drop_caches的詳細(xì)文檔如下：
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 添加如下選項(xiàng)后就不會(huì)內(nèi)存持續(xù)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
