linux-kernel - Re: [Patch V3 0/3] Enable irqs when waiting for rwlocks

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Message-Id: <1228307798.1009.1.camel@nathan.suse.cz>
Date:	Wed, 03 Dec 2008 13:36:38 +0100
From:	Petr Tesarik <ptesarik@...e.cz>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Robin Holt <holt@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org,
	tee@....com, mingo@...e.hu, linux-arch@...r.kernel.org
Subject: Re: [Patch V3 0/3] Enable irqs when waiting for rwlocks

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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