Re: Wierd context-switching issue on Xeon patch for 7.4.1

More data....

On a dual xeon with HTT enabled:

I tried increasing the NUM_SPINS to 1000 and it works better.

NUM_SPINLOCKS    CS    ID    pgbench

100        250K    59%    230 TPS
1000        125K    55%    228 TPS

This is certainly heading in the right direction ? Although it looks
like it is highly dependent on the system you are running on.

--dc--



On Wed, 2004-04-21 at 22:53, Josh Berkus wrote:
> Tom,
>
> > As far as I can tell, this does reduce the rate of semop's
> > significantly, but it does so by bringing the overall processing rate
> > to a crawl :-(.  I see 97% CPU idle time when using this patch.
> > I believe what is happening is that the select() delay in s_lock.c is
> > being hit frequently because the spin loop isn't allowed to run long
> > enough to let the other processor get out of the spinlock.
>
> Also, I tested it on production data, and it reduces the CSes by about 40%.
> An improvement, but not a magic bullet.
--
Dave Cramer
519 939 0336
ICQ # 14675561