Re: [PATCH] don't use ld.bias

[jbarnes@sgi.com (Jesse Barnes)]

On Mon, Jul 21, 2003 at 05:15:39PM -0700, Chen, Kenneth W wrote:
> > Patch to fix spin_lock to not use ld.bias since it causes a bunch of
> bus
> > activity that hurts scalability when a lock is contended.
> 
> It's dangerous to say something without knowing the whole context, but I
> can't resist asking why not fix the contended lock area instead?  Sounds
> like you have some serious contention.

Maybe I shouldn't have said 'contended'.  This causes problems even when
a lock is nearly uncontended.  I agree that fixing lock contention is a
good idea, but as I read this code, it'll only make the very best case
(totally uncontended) only a little better than if the ld.bias were just
an ld and it makes the average and contended cases _much_ worse.

I can get some data if you're not convinced by reading the code :)

Thanks,
Jesse