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Subject: Re: [patch 2/2] x86,pat Convert memtype_lock into an rw_lock.
From: Peter Zijlstra <peterz@infradead.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, "holt@sgi.com" <holt@sgi.com>,
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Date: Wed, 24 Mar 2010 12:32:27 +0100
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On Wed, 2010-03-17 at 16:19 -0800, Suresh Siddha wrote:
> On Wed, 2010-03-17 at 12:51 -0700, H. Peter Anvin wrote:
> > Well, as you know :) tglx and I are on the road ... I'll try to get to it on Friday before I take off again.
> 
> Also I talked to Thomas about this rwlock conversion and he referred to
> RT issues with rwlock. And the best is to avoid this using RCU.

Its not just RT, even for mainline rwlock_t is a massive pain and often
is no better (actually worse) than a spinlock due to the massive
cacheline bouncing it introduces.