清理缓存

procsysvmdrop_caches清理缓存

1.使⽤⽅法

/proc/sys/vm/drop_caches默认是0

#echo1>/proc/sys/vm/drop_caches;freepagecache,u

#echo2>/proc/sys/vm/drop_caches;freedentriesandinodes

#echo3>/proc/sys/vm/drop_caches;freepagecache,dentriesandinodes

注意：使⽤之前需要先sync，将缓存刷到磁盘中。

2.实验

单位：MB

#free-m

totaludfreesharedbuff/cacheavailable

Mem:8791413

Swap:000

#cp/etc/*/mytest/

#free-m

totaludfreesharedbuff/cacheavailable

Mem:81011412

Swap:000

过⼀段时间：

#free-m

totaludfreesharedbuff/cacheavailable

Mem:81011412

Swap:0

#cat/proc/sys/vm/drop_caches

0

#sync

#echo3>/proc/sys/vm/drop_caches

#free-m

totaludfreesharedbuff/cacheavailable

Mem:8371413

Swap:

3.写个脚本做这个事情

#catcleanup_

#!/bin/sh

#drop_cachesforevery5mins

drop_caches(){

echo"Dropcaches."

sync

echo3>/proc/sys/vm/drop_caches&

return0

}

whiletrue;do

sleep300

drop_caches

done

exit0

4.结论

Linux内核默认保持drop_cache的值是0，不建议经常修改它。