通過free命令可以檢視系統記憶體使用情況：

free -m
              total        used        free      shared  buff/cache   available
Mem:           7983        2427        5155          26         400        5272
Swap:          8191          21        8170

buff/cache為快取部分，在統計memory佔用情況時，需要注意這一個值。通過以下命令可以釋放快取：

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.

上面方法需要使用者具有root許可權，如果不是root，但有sudo許可權，可以通過sysctl命令進行設定：

$sync
$sudo sysctl -w vm.drop_caches=3
$sudo sysctl -w vm.drop_caches=0 #恢復預設cache策略

使用這樣的cache策略後，進行信用證的壓力測試，Linux下該程序的記憶體佔用率不再隨時間繼續上升。