Messages in this thread | | | Date | Fri, 21 Jul 2023 23:19:44 +0100 | From | Qais Yousef <> | Subject | Re: [PATCH] cpufreq: schedutil: next_freq need update when cpufreq_limits changed |
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On 07/19/23 21:05, Xuewen Yan wrote: > When cpufreq's policy is single, there is a scenario that will > cause sg_policy's next_freq to be unable to update. > > When the cpu's util is always max, the cpufreq will be max, > and then if we change the policy's scaling_max_freq to be a > lower freq, indeed, the sg_policy's next_freq need change to > be the lower freq, however, because the cpu_is_busy, the next_freq > would keep the max_freq. > > For example: > The cpu7 is single cpu: > > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # while true;do done& > [1] 4737 > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # taskset -p 80 4737 > pid 4737's current affinity mask: ff > pid 4737's new affinity mask: 80 > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq > 2301000 > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_cur_freq > 2301000 > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # echo 2171000 > scaling_max_freq > unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq > 2171000 > > At this time, the sg_policy's next_freq would keep 2301000. > > To prevent the case happen, add the judgment of the need_freq_update flag. > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > Co-developed-by: Guohua Yan <guohua.yan@unisoc.com> > Signed-off-by: Guohua Yan <guohua.yan@unisoc.com> > --- > kernel/sched/cpufreq_schedutil.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > index 4492608b7d7f..458d359f5991 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -350,7 +350,8 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time, > * Except when the rq is capped by uclamp_max. > */ > if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) && > - sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq) { > + sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq && > + !sg_policy->need_freq_update) {
What about sugov_update_single_perf()? It seems to have the same problem, no?
LGTM otherwise.
Cheers
-- Qais Yousef
> next_f = sg_policy->next_freq; > > /* Restore cached freq as next_freq has changed */ > -- > 2.25.1 >
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