Messages in this thread Patch in this message | | | Subject | Re: WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453 | From | Dietmar Eggemann <> | Date | Fri, 30 Jul 2021 14:22:18 +0200 |
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On 29/07/2021 16:38, Dietmar Eggemann wrote: > On 29/07/2021 14:36, Bruno Goncalves wrote: >> On Wed, Jul 28, 2021 at 5:55 PM Dietmar Eggemann >> <dietmar.eggemann@arm.com> wrote: >>> >>> On 28/07/2021 15:11, Bruno Goncalves wrote: > > [...] > >>> Can't reproduce it on my Juno (arm64) (slow-switching (scpi-cpufreq >>> driver)). >> >> We seem to be able to reproduce this only on Ampere Altra machines, >> specifically on mtjade and mtsnow cpus. >> >> # cpupower frequency-info >> analyzing CPU 0: >> driver: cppc_cpufreq >> CPUs which run at the same hardware frequency: 0 >> CPUs which need to have their frequency coordinated by software: 0 >> maximum transition latency: Cannot determine or is not supported. >> hardware limits: 1000 MHz - 2.80 GHz >> available cpufreq governors: conservative ondemand userspace >> powersave performance schedutil >> current policy: frequency should be within 2.00 GHz and 2.80 GHz. >> The governor "schedutil" may decide which speed to use >> within this range. >> current CPU frequency: 1.55 GHz (asserted by call to hardware) >> >> # ps -eTo comm,pid,pri,class | grep sugov >> sugov:0 1082 140 DLN >> sugov:1 1085 140 DLN >> ... >> sugov:78 1319 140 DLN >> sugov:79 1320 140 DLN > > Thanks! In the meantime I got access to an Ampere Altra so I can try > 5.14.0-rc1 later today.
The task causing this seem to be the new `cppc_fie` DL task introduced by commit 1eb5dde674f5 "cpufreq: CPPC: Add support for frequency invariance" in v5.14-rc1.
With `CONFIG_ACPI_CPPC_CPUFREQ_FIE=y` and schedutil cpufreq governor on slow-switching system:
DL task curr=`sugov:X` makes p=`cppc_fie` migrate and since it is in `non_contending` state, migrate_task_rq_dl() calls
sub_running_bw()->__sub_running_bw()->cpufreq_update_util()-> rq_clock()->assert_clock_updated()
on p.
Can you try this snippet? It should fix it.
--8<--
From: Dietmar Eggemann <dietmar.eggemann@arm.com> Date: Fri, 30 Jul 2021 14:03:40 +0200 Subject: [PATCH] sched/deadline: Fix missing clock update in migrate_task_rq_dl()
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> --- kernel/sched/deadline.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index aaacd6cfd42f..4920f498492f 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1733,6 +1733,7 @@ static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused */ raw_spin_rq_lock(rq); if (p->dl.dl_non_contending) { + update_rq_clock(rq); sub_running_bw(&p->dl, &rq->dl); p->dl.dl_non_contending = 0; /* -- 2.25.1
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