From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: KVM Processor cache size
Date: Mon, 02 Aug 2010 17:23:21 -0500
Message-ID: <4C574559.40509@codemonkey.ws>
References: <AANLkTiks1uN+saWo-roToqHLDHbTD5ZvX6U-ZvYk7=qq@mail.gmail.com> <4C56BF6F.9040402@amd.com> <4C56CCFB.204@redhat.com>
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Cc: Andre Przywara <andre.przywara@amd.com>,
	Ricardo Martins <ricardo.martins.br@gmail.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
To: Ulrich Drepper <drepper@redhat.com>
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On 08/02/2010 08:49 AM, Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
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> On 08/02/2010 05:51 AM, Andre Przywara wrote:
>   =20
>> Do you have a use case for the cache size or is this just out of cur=
iosity?
>>     =20
> 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=
=20
migration with -cpu host too if we don't guarantee these values remain=20
stable across migration...

Regards,

Anthony Liguori

>    Even the synthetic
> CPU provided by qemu should have a more realistic value.
>
> - --=20
> =E2=9E=A7 Ulrich Drepper =E2=9E=A7 Red Hat, Inc. =E2=9E=A7 444 Castro=
 St =E2=9E=A7 Mountain View, CA =E2=9D=96
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>   =20