From: Andi Kleen <andi@firstfloor.org>
To: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <js1304@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
andi@firstfloor.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH] mm: introduce numa_zero_pfn
Date: Wed, 12 Dec 2012 21:15:29 +0100 [thread overview]
Message-ID: <20121212201529.GD16230@one.firstfloor.org> (raw)
In-Reply-To: <0000013b90beeb93-87f65a09-0cc3-419f-be26-5271148cb947-000000@email.amazonses.com>
> I would expect a processor to fetch the zero page cachelines from the l3
> cache from other sockets avoiding memory transactions altogether. The zero
> page is likely in use somewhere so no typically no memory accesses should
> occur in a system.
It depends on how effectively the workload uses the caches. If something
is a cache pig of the L3 cache, then even shareable cache lines may need
to be refetched regularly.
But if your workloads spends a significant part of its time reading
from zero page read only data there is something wrong with the workload.
I would do some data profiling first to really prove that is the case.
-Andi
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next prev parent reply other threads:[~2012-12-12 20:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-12 17:03 [PATCH] mm: introduce numa_zero_pfn Joonsoo Kim
2012-12-12 18:09 ` Kirill A. Shutemov
2012-12-12 20:12 ` Christoph Lameter
2012-12-12 20:15 ` Andi Kleen [this message]
2012-12-17 13:58 ` JoonSoo Kim
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