Re: [PATCH] x86: Add clflush before monitor for Intel 7400 series- v2

From: Ingo Molnar
Date: Mon Feb 09 2009 - 05:16:19 EST



* Pallipadi, Venkatesh <venkatesh.pallipadi@xxxxxxxxx> wrote:

> For Intel 7400 series CPUs, the recommendation is to use a clflush on the
> monitored address just before monitor and mwait pair [1]. This clflush makes sure
> that there are no false wakeups from mwait when the monitored address was recently
> written to.
>
> [1] "MONITOR/MWAIT Recommendations for Intel Xeon Processor 7400 series"
> section in specification update document of 7400 series
> http://download.intel.com/design/xeon/specupdt/32033601.pdf
>
> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
>
> ---
>
> Earlier patch:
> http://marc.info/?l=linux-kernel&m=122341330606025&w=2
>
> Current changes:
> Minor modification based on Peter's comment
>
> arch/x86/include/asm/cpufeature.h | 1 +
> arch/x86/kernel/cpu/intel.c | 3 +++
> arch/x86/kernel/process.c | 6 ++++++
> 3 files changed, 10 insertions(+)

applied to tip/x86/urgent, thanks Venki!

Ingo
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