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Date: Thu, 12 Aug 2004 11:09:24 +0200
From: Andi Kleen <ak@suse.de>
Subject: Re: clear_user_highpage()
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To: "David S. Miller" <davem@redhat.com>
Cc: torvalds@osdl.org, linux-arch@vger.kernel.org
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On Wed, 11 Aug 2004 19:45:45 -0700
"David S. Miller" <davem@redhat.com> wrote:

> On Thu, 12 Aug 2004 04:08:25 +0200
> Andi Kleen <ak@suse.de> wrote:
> 
> > I discovered this the hard way on Opteron too. At some point
> > I was doing clear_page using cache bypassing write combining stores.
> > That was done because it was faster in microbenchmarks that just
> > tested the function. But on actual macro benchmarks it was quite
> > bad because the applications were eating cache misses all the time.
> 
> Do these cache-bypassing stores use the L2 cache on a hit?

No, they invalidate the cache.

-Andi