Re: [MM] Make mm counters per cpu instead of atomic

Christoph Lameter
2009-11-24T15:18:41Z

On Tue, 24 Nov 2009, Zhang, Yanmin wrote:

> > True.... We need to find some alternative to per cpu data to scale mmap
> > sem then.
> I ran lots of benchmarks such like specjbb2005/hackbench/tbench/dbench/iozone
> /sysbench_oltp(mysql)/aim7 against percpu tree(based on 2.6.32-rc7) on a 4*8*2 logical
> cpu machine, and didn't find big result difference between with your patch and without
> your patch.

This affects loads that heavily use mmap_sem. You wont find too many
issues in tests that do not run processes with a large thread count and
cause lots of faults or uses of get_user_pages(). The tests you list are
not of that nature.