The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 9e0bc36ab07c550d791bf17feeb479f1dfc42d89
Gitweb: https://git.kernel.org/tip/9e0bc36ab07c550d791bf17feeb479f1dfc42d89
Author: Xuewen Yan <xuewen.yan@xxxxxxxxxx>
AuthorDate: Wed, 19 Jul 2023 21:05:27 +08:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 05 Oct 2023 22:09:50 +02:00
cpufreq: schedutil: Update next_freq when cpufreq_limits change
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 a 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 stay at 2301000, which
is wrong.
To fix this, add a check for the ->need_freq_update flag.
[ mingo: Clarified the changelog. ]
Co-developed-by: Guohua Yan <guohua.yan@xxxxxxxxxx>
Signed-off-by: Xuewen Yan <xuewen.yan@xxxxxxxxxx>
Signed-off-by: Guohua Yan <guohua.yan@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230719130527.8074-1-xuewen.yan@xxxxxxxxxx
---
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 4492608..458d359 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) {
next_f = sg_policy->next_freq;
/* Restore cached freq as next_freq has changed */
|