On Wed, Jan 08, 2014 at 01:48:58PM +0000, Mel Gorman wrote: > Adding LKML to the list as this -stable snifftest has identified an > upstream regression. > This is a false alarm. The test machine in question was originally installed based on a beta version of openSUSE 13.1. It included a package by default that set default malloc parameters that I was not aware. Normally the package is there to catch bugs during beta testing and removed before a GA release but it's left in place if a user does a distribution update. With the debugging RPM installed, the free paths contended on a global mutex in glibc. Ebizzy had been classified as a CPU intensive and memory free intensive benchmark (not that common) but turbostat showed that the CPUs were over 95% of the time in C6 and mpstat verified that the CPUs were mostly idle. It did not take long to see that everything was blocked waiting on a futex and to identify where it was in glibc. It's only a factor when malloc debugging is enabled so normally people would not see it. The "regression" is because CPUs are reaching C6 as they should and there is a delay when exiting it. This is behaving as designed and fixing this would involve doing something stupid. Once the problem RPM was removed ebizzy performed as expected. 3.13-rc7, the revert and forcing max_cstate=1 all have similar performance. Sorry about the noise. -- Mel Gorman SUSE Labs -- 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