Messages in this thread | | | Date | Mon, 15 Feb 2021 15:10:46 +0800 | From | Yue Hu <> | Subject | Re: [PATCH] cpufreq: schedutil: Don't use the limits_changed flag any more |
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On Mon, 15 Feb 2021 12:00:08 +0530 Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 14-02-21, 11:44, Yue Hu wrote: > > On Fri, 12 Feb 2021 17:14:03 +0100 > > "Rafael J. Wysocki" <rafael@kernel.org> wrote: > > > This may be running in parallel with sugov_update_next_freq() on a > > > different CPU, so the latter may clear need_freq_update right > > > after it has been set here unless I'm overlooking something. > > > > Whether this logic is also happening for limits_changed in > > sugo_should_update_freq() or not? > > It is but it shouldn't have any side effects as we calculate the next > frequency after cleaning the limits_changed flag. Your patch would > have been fine, but it is not anymore because of commit 23a881852f3e > ("cpufreq: schedutil: Don't skip freq update if need_freq_update is > set"). > > It made a considerable change after which your patch adds a bug. With > 23a881852f3e, need_freq_update is updated/cleared after the next > frequency is calculated, while earlier it was cleared before it. And > so even with the race condition taking place, there were no issues. >
Okay, clear.
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