Subject: Re: [Patch V3 0/3] Enable irqs when waiting for rwlocks
From: Petr Tesarik <ptesarik@suse.cz>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Robin Holt <holt@sgi.com>, Andrew Morton <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, tee@sgi.com,
       mingo@elte.hu, linux-arch@vger.kernel.org
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References: <20081104122405.046233722@attica.americas.sgi.com>
	 <20081202161311.ae3376cb.akpm@linux-foundation.org>
	 <20081203113744.GE8970@sgi.com>  <1228307117.9673.232.camel@twins>
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Organization: SUSE LINUX
Date: Wed, 03 Dec 2008 13:36:38 +0100
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Peter Zijlstra píše v St 03. 12. 2008 v 13:25 +0100:
> On Wed, 2008-12-03 at 05:37 -0600, Robin Holt wrote:
> > > It's a bit regrettable to have different architectures behaving in
> > > different ways.  It would be interesting to toss an x86_64
> > > implementation into the grinder, see if it causes any problems, see if
> > > it produces any tangible benefits.  Then other architectures might
> > > follow.  Or not, depending on the results ;)
> > 
> > I personally expect SGI to work on this for x86_64 in the future.
> > Once we actually start testing systems with 128 and above cpus, I
> > would expect to see these performance issues needing to be addressed.
> > Until then, it is just a theoretical.
> 
> Personally I consider this a ugly hack and would love to see people
> solve the actual problem and move away from rwlock_t, its utter rubbish.

Me too, but we don't have that clean and nice solution today, but what
we _do_ have today are the machines which break badly when interrupts
are disabled for the whole duration of taking a rwlock_t. :(

Feel free to rewrite all users of rwlock_t. I'll appreciate it, oh so
very much.

Petr

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