Prakash Sawarkar: Kernel 3.8 Released, how to Compile in Redhat, CenOS and Fedora..

Kernel 3.8 Released, how to Compile in Redhat, CentOS and Fedora.

Sunday, 19 April 2009

Reducing.. Kernel Page cache, Inode and dentry caches.

Kernel 2.6 never provide a mechanism to have the kernel drop the page cache and/or inode and dentry caches on command, which can help free up a lot of memory.

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 free-able, the user should run "sync" first in order to make sure all cached objects are freed.

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