Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [genirq] cbe16f35be: will-it-scale.per_thread_ops -5.2% regression | Date | Tue, 27 Apr 2021 21:37:11 +0200 |
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On Tue, Apr 27 2021 at 13:42, Thomas Gleixner wrote: > On Tue, Apr 27 2021 at 17:00, kernel test robot wrote: >> FYI, we noticed a -5.2% regression of will-it-scale.per_thread_ops due to commit: >> >> commit: cbe16f35bee6880becca6f20d2ebf6b457148552 ("genirq: Add IRQF_NO_AUTOEN for request_irq/nmi()") >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master > > this is the second report in the last week which makes not a lot of sense. > And this oneis makes absolutely no sense at all. > > This commit affects request_irq() and the related variants and has > exactly ZERO influence on anything related to that test case simply > because. > > I seriously have to ask the question whether this test infrastructure is > actually measuring what it claims to measure. > > As this commit clearly _cannot_ have the 'measured' side effect, this > points to some serious issue in the tests or the test infrastructure > itself.
Just to illustrate the issue:
I ran the will-it-scale getppid1 test manually against plain v5.12 and against v5.12 + cherrypicked cbe16f35be, i.e. the "offending" commit.
The result for a full run is just in the noise:
average: < 0.1% minimum: -0.22% maximum: 0.29%
IOW very far away from -5.2%.
That's an order of magnitude off.
And no, I'm not going to run that lkp-test muck simply because it's unusable and the test result of will-it-scale itself is clear enough.
Thanks,
tglx
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