tkh’s blog

New Kernel Feature

May 4, 2006 on 1:54 pm | In Computer, Linux | No Comments

I stumbled on the KernelNewbies Wiki about a new feature in kernel 2.6.16:

Add /proc/sys/vm/drop_caches. Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free. This is mainly useful for benchmarking, for getting consistent results between filesystem benchmarks without rebooting. 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.

It’s sweet.