On 2022/8/24 18:46, Johannes Weiner wrote:
> On Wed, Aug 24, 2022 at 04:18:26PM +0800, Chengming Zhou wrote:
>> @@ -903,6 +903,36 @@ void psi_task_switch(struct task_struct *prev, struct task_struct *next,
>> }
>> }
>>
>> +#ifdef CONFIG_IRQ_TIME_ACCOUNTING
>> +void psi_account_irqtime(struct task_struct *task, u32 delta)
>> +{
>> + int cpu = task_cpu(task);
>> + void *iter = NULL;
>> + struct psi_group *group;
>> + struct psi_group_cpu *groupc;
>> + u64 now;
>> +
>> + if (!task->pid)
>> + return;
>> +
>> + now = cpu_clock(cpu);
>> +
>> + while ((group = iterate_groups(task, &iter))) {
>> + groupc = per_cpu_ptr(group->pcpu, cpu);
>> +
>> + write_seqcount_begin(&groupc->seq);
>> +
>> + record_times(groupc, now);
>> + groupc->times[PSI_IRQ_FULL] += delta;
>> +
>> + write_seqcount_end(&groupc->seq);
>> +
>> + if (group->poll_states & (1 << PSI_IRQ_FULL))
>> + psi_schedule_poll_work(group, 1);
>> + }
>
> Shouldn't this kick avgs_work too? If the CPU is otherwise idle,
> times[PSI_IRQ_FULL] would overflow after two missed averaging runs.
If the CPU is idle, task->pid == 0, so no times[PSI_IRQ_FULL] would accumulate?
I was thinking if task->pid != 0, avgs_work should be active.
Not sure, maybe I missed something.
>
> avgs_work should probably also self-perpetuate when PSI_IRQ_FULL is in
> changed_states. (Looking at that code, I think it can be simplified:
> delete nonidle and do `if (changed_states) schedule_delayed_work()`.)
```
collect_percpu_times(group, PSI_AVGS, &changed_states);
nonidle = changed_states & (1 << PSI_NONIDLE);
if (nonidle) {
schedule_delayed_work(dwork, nsecs_to_jiffies(
group->avg_next_update - now) + 1);
}
```
Yes, changed_states include PSI_IRQ_FULL, here we only check nonidle
= changed_states & (1 << PSI_NONIDLE), so it will not restart
if only PSI_IRQ_FULL?
If use `if (changed_states) schedule_delayed_work()`, avgs_work will
self-restart when only PSI_IRQ_FULL changes?
Thanks!
