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

From: Mallick, Asit K <asit.k.mallick_at_intel.com>
Date: 2003-07-23 14:40:02
It does make sense to not use the ld.bias in the spinlock, it will make
more cacheline bouncing in a larger SMP system.
Thanks,
Asit


> -----Original Message-----
> From: Jesse Barnes [mailto:jbarnes@sgi.com] 
> Sent: Tuesday, July 22, 2003 6:12 AM
> To: Chen, Kenneth W
> Cc: linux-ia64@vger.kernel.org; davidm@hpl.hp.com
> Subject: Re: [PATCH] don't use ld.bias
> 
> 
> 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
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Received on Wed Jul 23 00:40:21 2003

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