From: Anthony Liguori <anthony@codemonkey.ws>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Andre Przywara <andre.przywara@amd.com>,
Ricardo Martins <ricardo.martins.br@gmail.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: KVM Processor cache size
Date: Mon, 02 Aug 2010 17:23:21 -0500 [thread overview]
Message-ID: <4C574559.40509@codemonkey.ws> (raw)
In-Reply-To: <4C56CCFB.204@redhat.com>
On 08/02/2010 08:49 AM, Ulrich Drepper wrote:
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> On 08/02/2010 05:51 AM, Andre Przywara wrote:
>
>> Do you have a use case for the cache size or is this just out of curiosity?
>>
> glibc uses the cache size information returned by cpuid to perform
> optimizations. For instance, copy operations which would pollute too
> much of the cache because they are large will use non-temporal
> instructions. There are real performance benefits.
I imagine that there would be real performance problems from doing live
migration with -cpu host too if we don't guarantee these values remain
stable across migration...
Regards,
Anthony Liguori
> Even the synthetic
> CPU provided by qemu should have a more realistic value.
>
> - --
> ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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> --
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next prev parent reply other threads:[~2010-08-02 22:23 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-02 11:45 KVM Processor cache size Ricardo Martins
2010-08-02 12:51 ` Andre Przywara
2010-08-02 13:08 ` Avi Kivity
2010-08-02 22:22 ` Anthony Liguori
2010-08-02 22:35 ` Andre Przywara
2010-08-02 23:38 ` Anthony Liguori
2010-08-03 5:38 ` Avi Kivity
2010-08-03 5:33 ` Avi Kivity
2010-08-02 22:25 ` Anthony Liguori
2010-08-02 22:54 ` Andre Przywara
2010-08-02 23:40 ` Anthony Liguori
2010-08-03 5:41 ` Avi Kivity
2010-08-02 13:49 ` Ulrich Drepper
2010-08-02 18:38 ` Ricardo Martins
2010-08-02 22:24 ` Andre Przywara
2010-08-02 22:15 ` Andre Przywara
2010-08-02 22:23 ` Anthony Liguori [this message]
2010-08-02 22:42 ` Andre Przywara
2010-08-02 23:36 ` Anthony Liguori
2010-08-03 6:25 ` Dor Laor
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