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Message-Id: <1173854614.19022.14.camel@localhost.localdomain>
Date: Wed, 14 Mar 2007 17:43:34 +1100
From: Rusty Russell <rusty@...tcorp.com.au>
To: Andi Kleen <ak@....de>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>,
lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Introduce load_TLS to the "for" loop.
On Tue, 2007-03-13 at 21:55 +0100, Andi Kleen wrote:
> On Tue, Mar 13, 2007 at 10:31:27AM -0700, Jeremy Fitzhardinge wrote:
> > Andi Kleen wrote:
> > > On Tue, Mar 13, 2007 at 05:39:36PM +1100, Rusty Russell wrote:
> > >
> > >> GCC (4.1 at least) unrolls it anyway, but I can't believe this code
> > >>
> > >
> > > Are you sure? Normally it doesn't unroll without -funroll-loops which
> > > the kernel does normally not set. Especially not with -Os builds.
> > >
> >
> > Does it matter either way in this case?
>
> It's in the middle of the context switch.
Well, the rest of __switch_to isn't "0PTIM1Z3D!!!" like this.
But even so, that's no excuse for crap code. If it had used memcpy, we
wouldn't be wasting cycles on this discussion.
Rusty.
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