Re: [rfc][patch] queued spinlocks (i386)

From: Andrew Morton
Date: Sat Mar 24 2007 - 17:42:16 EST


> On Fri, 23 Mar 2007 11:32:44 +0100 Nick Piggin <npiggin@xxxxxxx> wrote:
>
> I'm not as concerned about the contended performance of spinlocks
>

The contended case matters. Back in 2.5.something I screwed up the debug
version of one of the locks (rwlock, iirc) - it was simply missing a
cpu_relax(), and some people's benchmarks halved.

> This was just something I had in mind when the hardware lock
> starvation issue came up

It looks like a good way to address the lru_lock starvation/capture
problem. But I think I'd be more comfortable if we were to introduce it as
a new lock type, rather than as a reimplementation of the existing
spin_lock(). Initially, at least.
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