Messages in this thread | | | Date | Thu, 19 Dec 2013 18:50:37 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86 idle: repair large-server 50-watt idle-power regression |
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On Thu, Dec 19, 2013 at 06:25:35PM +0100, Peter Zijlstra wrote: > On Thu, Dec 19, 2013 at 06:07:41PM +0100, Ingo Molnar wrote: > > Likewise, having a barrier before the MONITOR looks sensible as well. > > I again have to disagree, one would expect monitor to flush all that is > required to start the monitor -- and it actually does so. As is > testified by this extra CLFLUSH being called a bug workaround.
SDM states that MONITOR is ordered like a LOAD, and a LOAD cannot pass a previous STORE to the same address.
That said; there's enough holes in there to swim a titanic through, seeing how MONITOR stares at an entire cacheline and LOAD/STORE order is specified on location, whatever that means.
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