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SubjectRe: [tip:x86/asm] x86/xor: Make virtualization friendly
On 01/25/2013 02:43 AM, tip-bot for Jan Beulich wrote:
> Commit-ID: 05fbf4d6fc6a3c0c3e63b77979c9311596716d10
> Gitweb: http://git.kernel.org/tip/05fbf4d6fc6a3c0c3e63b77979c9311596716d10
> Author: Jan Beulich <JBeulich@suse.com>
> AuthorDate: Fri, 2 Nov 2012 14:21:23 +0000
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Fri, 25 Jan 2013 09:23:51 +0100
>
> x86/xor: Make virtualization friendly
>
> In virtualized environments, the CR0.TS management needed here
> can be a lot slower than anticipated by the original authors of
> this code, which particularly means that in such cases forcing
> the use of SSE- (or MMX-) based implementations is not desirable
> - actual measurements should always be done in that case.
>
> For consistency, pull into the shared (32- and 64-bit) header
> not only the inclusion of the generic code, but also that of the
> AVX variants.
>

This patch is wrong and should be dropped. I verified it with the KVM
people that they do NOT want this change. It is a Xen-specific problem.

-hpa




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