Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Tue, 27 Sep 2016 02:21:34 +0200 | Subject | Re: Regression in 4.8 - CPU speed set very low |
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On Tue, Sep 27, 2016 at 1:53 AM, Larry Finger <Larry.Finger@lwfinger.net> wrote: > On 09/26/2016 05:16 PM, Rafael J. Wysocki wrote: >> >> On Tue, Sep 27, 2016 at 12:09 AM, Larry Finger > > <Larry.Finger@lwfinger.net> wrote: >> >> >> Maybe it's better to try diagnose the problem instead of spending more >> time on bisection. > > > In my original post, I asked for such help, but nothing until today. I had > no idea what to check, but now I have a better idea. > >> I'd like to know whether or not 4.7 was definitely good, though. > > > I never saw this problem with 4.7, but given the difficulty in triggering > the problem, my tests may not have been definitive. >> >> >>> If it is one of them, it may be a while before I dare call this one >>> "good". >>> In one respect, that is good as I will be traveling tomorrow and >>> Wednesday. >> >> >> What does "cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver" say? > > > intel_pstate
You probably don't need to worry about all of the cpufreq changes in 4.8-rc, then. Only a few of them affect intel_pstate and I don't see how any of them may lead to the observed symptoms.
First off, if you have a reproducer, please run it on 4.7 and see if you can trigger the issue in there.
Second, it would be good to have a look at the output from the cpu_frequency and pstate_sample tracepoints around when the issue triggers. The pstate_sample one would be more interesting.
But for both we need a reproducer anyway.
It also would be good to rule out the thermal throttling (as per the Srinivas' comments).
For now, please tell me what's in /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq
Thanks, Rafael
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