Messages in this thread | | | Date | Tue, 24 Dec 2019 11:08:35 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH v4 1/6] x86,sched: Add support for frequency invariance |
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On 12/23/19 17:16, Doug Smythies wrote: > Yes, it fixes the schedutil governor behaving like the performance governor > problem on my i7-2600K test system. > > I re-ran the tests several times, and re-booted back to the stock (problem) > kernel to verify incorrect schedutil governor performance (i.e. I toggled > back and forth, 2 times for each of 2 kernels, tests 1 and 2, total 8 tests). > Kernel 5.5-rc2: 4 tests FAILED (as expected). > Kernel 5.5-rc2 + this patch: 4 tests PASSED.
Great! Thanks for testing it, I'll send a proper patch shortly.
> > Accidentally tested: > Kernel 5.5-rc2 + this patch + command line "cgroup_no_v1=all": 1 test PASS.
I think this cgroup_no_v1 is a happy accident. It has nothing to do with the fault, but for your case maybe helped observing things in a better way. FWIW, I reproduced the issue on Juno Arm64 using Debian and Buildroot rootfs.
What is actually required to trigger the bug is to create a cpu controller and add all system tasks to it to create some noise - which Ubuntu and Debian do by default at boot time. In Buildroot when I did that manually I could see the frequency going to max most of the time.
I'll add away to test this scenario.
Thanks for your detailed report.
Happy holidays!
-- Qais Yousef
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