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Re: [PATCH v5 4/5] x86: use mb() around clflush

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH v5 4/5] x86: use mb() around clflush
Date 2016-01-28 19:30 +0100
Message-ID <qVZur-7o4-15@gated-at.bofh.it> (permalink)
References <qVYf0-6zx-21@gated-at.bofh.it> <qVYf1-6zx-41@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Jan 28, 2016 at 07:02:51PM +0200, Michael S. Tsirkin wrote:
> commit f8e617f4582995f7c25ef25b4167213120ad122b ("sched/idle/x86:
> Optimize unnecessary mwait_idle() resched IPIs") adds
> memory barriers around clflush, but this seems wrong
> for UP since barrier() has no effect on clflush.
> We really want mfence so switch to mb() instead.
> 
> Cc: Mike Galbraith <bitbucket@online.de>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

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Thread

[PATCH v5 0/5] x86: faster smp_mb()+documentation tweaks "Michael S. Tsirkin" <mst@redhat.com> - 2016-01-28 18:10 +0100
  [PATCH v5 5/5] x86: drop mfence in favor of lock+addl "Michael S. Tsirkin" <mst@redhat.com> - 2016-01-28 18:10 +0100
  [PATCH v5 4/5] x86: use mb() around clflush "Michael S. Tsirkin" <mst@redhat.com> - 2016-01-28 18:10 +0100
    Re: [PATCH v5 4/5] x86: use mb() around clflush Peter Zijlstra <peterz@infradead.org> - 2016-01-28 19:30 +0100
    [tip:locking/core] locking/x86: Use mb() around clflush() "tip-bot for Michael S. Tsirkin" <tipbot@zytor.com> - 2016-01-29 12:40 +0100
  [PATCH v5 1/5] x86: add cc clobber for addl "Michael S. Tsirkin" <mst@redhat.com> - 2016-01-28 18:10 +0100
    [tip:locking/core] locking/x86: Add cc clobber for ADDL "tip-bot for Michael S. Tsirkin" <tipbot@zytor.com> - 2016-01-29 12:40 +0100
  [PATCH v5 2/5] x86: drop a comment left over from X86_OOSTORE "Michael S. Tsirkin" <mst@redhat.com> - 2016-01-28 18:10 +0100
    [tip:locking/core] locking/x86:   Drop a comment left over from X86_OOSTORE "tip-bot for Michael S. Tsirkin" <tipbot@zytor.com> - 2016-01-29 12:40 +0100

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