Messages in this thread | | | Date | Tue, 07 Oct 2008 14:09:12 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: Add clflush before monitor for Intel 7400 series |
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Venki Pallipadi 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@intel.com>
This seems very expensive. It really makes me wonder if it wouldn't just be better to either declare monitor/mwait non-functional on this chip, or make sure that mwaits can handle false wakeups.
-hpa
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