On Tue, 2014-01-14 at 09:01 +0100, Mike Galbraith wrote: > On Tue, 2014-01-14 at 02:31 -0500, Len Brown wrote: > > > This is a false alarm. > > > > Thanks for the follow-up, Mel. > > > > Agreed, it makes no sense for ebizzy measure 'throughput', when a > > library debug bottleneck > > prevents it from scaling past 3% CPU utilization. > > > > Still, the broken configuration did find a difference due to the > > addition of CLFLUSH on this box. > > It makes me wonder if we will find issues on workloads that may depend > > on the latency > > of idle entry/exit, or perhaps sensitivity to the state of the cache > > line containing thread_info->flags. > > > > If somebody runs into such a workload, please try changing this 1 line > > of intel_idle.c to limit > > the CLFLUSH to C-states deeper than C1E, and let me know what you see. > > > > - if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) > > + if ((eax > 1) && this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR)) > > clflush((void *)¤t_thread_info()->flags); > > Hm, seems any high frequency switcher scheduling cross-core (pipe-test, > or maybe a tbench pair) should show the cost to an affected box. Oh yeah.. :) unless of course it's a Q6600 (poke poke). -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html