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Re: [Qemu-devel] [PATCH] resent: x86/cpuid: propagate further CPUID leaf
Re: [Qemu-devel] [PATCH] resent: x86/cpuid: propagate further CPUID leafs when -cpu host
Tue, 25 May 2010 10:27:58 +0300
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On 05/25/2010 01:10 AM, Anthony Liguori wrote:
On 05/21/2010 02:50 AM, Andre Przywara wrote:
-cpu host currently only propagates the CPU's family/model/stepping,
the brand name and the feature bits.
Add a whitelist of safe CPUID leafs to let the guest see the actual
CPU's cache details and other things.
Signed-off-by: Andre Przywara<address@hidden>
The problem I can see is that this greatly increases the chances of
problems with live migration since we don't migrate the cpuid state.
-cpu host is already problematic for live migration.
Are you talking about the state maintained by the cpuid instruction?
Yes, we need to migrate those bits.
What's the benefit of exposing this information to the guest?
Some algorithms adjust themselves based on the cache size. If you have
several passes over a large data set, it's often better to run each set
of passes on a subset of the dataset that fits in cache, then stitch the
error compiling committee.c: too many arguments to function