Messages in this thread | | | Subject | Re: Regression in 4.8 - CPU speed set very low | From | Larry Finger <> | Date | Mon, 26 Sep 2016 21:53:10 -0500 |
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On 09/26/2016 08:30 PM, Srinivas Pandruvada wrote: > On Mon, 2016-09-26 at 19:48 -0500, Larry Finger wrote: >> On 09/26/2016 07:21 PM, Rafael J. Wysocki wrote: >>> >>> On Tue, Sep 27, 2016 at 1:53 AM, Larry Finger <Larry.Finger@lwfinge >>> r.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. >> I'm running 4.8-rc7 at the moment hoping to trigger the problem and >> get the data >> requested by Srinivas. Once I get that, I will try 4.7 again. >>> >>> >>> 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. >> I do not have a reliable reproducer. The condition has always >> happened when >> running a high-compute job such as a 'make -j8' on the kernel, or >> building the >> RPM for openSUSE's implementation of VirtualBox. The latter is what >> I'm using >> for most of my testing. >> >>> >>> 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 >> 800000 > Your effective freq is lower than 800MHz. One of the possible reason is > thermal throttling. > > What distro you are using?
openSUSE Leap 42.1.
Larry
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