Re: WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453
From: Bruno Goncalves <hidden>
Date: 2021-07-30 15:23:32
Also in:
lkml
On Fri, Jul 30, 2021 at 2:22 PM Dietmar Eggemann [off-list ref] wrote:
On 29/07/2021 16:38, Dietmar Eggemann wrote:quoted
On 29/07/2021 14:36, Bruno Goncalves wrote:quoted
On Wed, Jul 28, 2021 at 5:55 PM Dietmar Eggemann [off-list ref] wrote:quoted
On 28/07/2021 15:11, Bruno Goncalves wrote:[...]quoted
quoted
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 DLNThanks! 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.
Thank you, I've tried the patch and it fixes the issue. Bruno
quoted hunk ↗ jump to hunk
--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
_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel