On Wed, Mar 16, 2016 at 05:00:07PM -0700, Laura Abbott wrote: > On 03/16/2016 03:46 PM, Greg Kroah-Hartman wrote: > >On Wed, Mar 16, 2016 at 03:27:57PM -0700, Laura Abbott wrote: > >>Hi, > >> > >>Fedora received a bug report > >>(https://bugzilla.redhat.com/show_bug.cgi?id=1317190) > >>of a major performance drop on various bench marks and general system > >>sluggishness with the 4.4.4 kernel update. The benchmarks were showing > >>a reduction to about 18% performance (not minor). > >> > >>Bisection showed the first bad commit was > >> > >>commit 774ac8b7eff69e0786970157de2157e68b22f456 > >>Author: Zhang Rui <rui.zh...@intel.com> > >>Date: Fri Oct 30 16:31:47 2015 +0800 > >> > >> Thermal: initialize thermal zone device correctly > >> commit bb431ba26c5cd0a17c941ca6c3a195a3a6d5d461 upstream. > >> After thermal zone device registered, as we have not read any > >> temperature before, thus tz->temperature should not be 0, > >> which actually means 0C, and thermal trend is not available. > >> In this case, we need specially handling for the first > >> thermal_zone_device_update(). > >> Both thermal core framework and step_wise governor is > >> enhanced to handle this. And since the step_wise governor > >> is the only one that uses trends, so it's the only thermal > >> governor that needs to be updated. > >> Tested-by: Manuel Krause <manuelkra...@netscape.net> > >> Tested-by: szegad <szega...@poczta.onet.pl> > >> Tested-by: prash <prash.n....@gmail.com> > >> Tested-by: amish <ammdispose-a...@yahoo.com> > >> Tested-by: Matthias <morpheusxyz...@yahoo.de> > >> Reviewed-by: Javi Merino <javi.mer...@arm.com> > >> Signed-off-by: Zhang Rui <rui.zh...@intel.com> > >> Signed-off-by: Chen Yu <yu.c.c...@intel.com> > >> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> > >> > >> > >> > >>Reverting this plus to other commits in the series (a67208e94d94 > >>"Thermal: handle thermal zone device properly during system sleep" > >>and 27f356149d59 "Thermal: do thermal zone update after a cooling > >>device registered") confirmed the performance was back to normal. > >> > >>Bugzilla has the full discussion but this comment from one of the > >>reporters sums it up: > >> > >>"In 4.4.3 and prior, my 2.40 MHz processor would fluctuate between > >>1000 and 3400 MHz. In 4.4.4, the processor would fluctuate between > >>400 and 700 MHz, according to /proc/cpuinfo. > >> > >>Setting /sys/devices/system/cpu/cpufreq/policy0/scaling_governor to > >>performance, instead of the default "powersave" forces the CPU to > >>2400 MHz, and improves performance greatly, but still not to the > >>same level as in 4.4.3." > >> > >>Any ideas? > > > >Is this same "slowdown" also seen in 4.5? > > > >thanks, > > > >greg k-h > > > > Yes, the same issue is seen on 4.5 according to the reporter.
Great, we are "bug compatible" :) Can you please work to get this resolved in Linus's tree and then we can backport the needed changes into the 4.4-stable release. Zhang, any ideas here? thanks, greg k-h
