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SubjectRe: [tip:x86/urgent] x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metal
On 04/10/2013 08:30 PM, tip-bot for Boris Ostrovsky wrote:
> Commit-ID: 511ba86e1d386f671084b5d0e6f110bb30b8eeb2
> Gitweb: http://git.kernel.org/tip/511ba86e1d386f671084b5d0e6f110bb30b8eeb2
> Author: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> AuthorDate: Sat, 23 Mar 2013 09:36:36 -0400
> Committer: H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Wed, 10 Apr 2013 11:25:10 -0700
>
> x86, mm: Patch out arch_flush_lazy_mmu_mode() when running on bare metal
>
> Invoking arch_flush_lazy_mmu_mode() results in calls to
> preempt_enable()/disable() which may have performance impact.
>
> Since lazy MMU is not used on bare metal we can patch away
> arch_flush_lazy_mmu_mode() so that it is never called in such
> environment.
>
> [ hpa: the previous patch "Fix vmalloc_fault oops during lazy MMU
> updates" may cause a minor performance regression on
> bare metal. This patch resolves that performance regression. It is
> somewhat unclear to me if this is a good -stable candidate. ]

I think this

https://lkml.org/lkml/2013/2/26/420

was also part of lazy mmu set of patches but is missing in the latest
batch of
commits.

-boris



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