通过free命令可以查看系统内存使用情况:
free -m
total used free shared buff/cache available
Mem: 7983 2427 5155 26 400 5272
Swap: 8191 21 8170
buff/cache为缓存部分,在统计memory占用情况时,需要注意这一个值。通过以下命令可以释放缓存:
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.
上面方法需要用户具有root权限,如果不是root,但有sudo权限,可以通过sysctl命令进行设置:
$sync
$sudo sysctl -w vm.drop_caches=3
$sudo sysctl -w vm.drop_caches=0 #恢复默认cache策略
使用这样的cache策略后,进行信用证的压力测试,Linux下该进程的内存占用率不再随时间继续上升。