How to clear memory cache in Linux [duplicate]

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Is there any command that by using I can clean the cache in RHEL?

I used this command:

sync; echo 3 > /proc/sys/vm/drop_caches

but it didn't work.

What's wrong with having something cached? It could speed up access to the cached data. — ott--, Dec 15 '12 at 14:43
There are many reasons why the cache wouldn’t be cleared. If the file is in use or if the cache size is due to tmpfs or ramfs. I have blogged about different possibilities of cache here. — Joe, Nov 18 '14 at 15:58
@ott--: simple, if you want to run high level performance tests (run version X of A against version X+1 of A to measure differences), how do you eliminate the file system cache from your testing? Because if you don't you'll skew your tests. You could by rebooting, but flushing the cache is certainly another option. — 0xC0000022L, Oct 20 '16 at 13:23

Renan · Accepted Answer · 2012-12-15 16:27:50Z

up vote 11 down vote accepted

Try sync; echo 1 > /proc/sys/vm/drop_caches.

Renan

13.5k64771

answered Dec 15 '12 at 16:06

Len

199212

sudo sh -c "echo 1 > /proc/sys/vm/drop_caches" – Kruser Dec 22 '17 at 8:34

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slash5toaster · Answer 2 · 2013-11-27 13:54:36Z

Depending on what you want to do you can use 1,2 or 3

drop_caches

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 not freeable, the user should run 'sync' first.

marked as duplicate by derobert, Satō Katsura, countermode, GAD3R, roaima Feb 22 '17 at 10:37