Re: [PATCH] tick/nohz: Make the idle_exittime update correctly

2021-02-19 Thread Frederic Weisbecker 
On Sat, Dec 05, 2020 at 05:41:52PM +0800, Yunfeng Ye wrote:
> The idle_exittime field of tick_sched is used to record the time when
> the idle state was left. but currently the idle_exittime is updated in
> the function tick_nohz_restart_sched_tick(), which is not always in idle
> state when nohz_full is configured.
> 
>   tick_irq_exit
> tick_nohz_irq_exit
>   tick_nohz_full_update_tick
> tick_nohz_restart_sched_tick
>   ts->idle_exittime = now;
> 
> So move to tick_nohz_stop_idle() to make the idle_exittime update
> correctly.
> 
> Signed-off-by: Yunfeng Ye 
> ---
>  kernel/time/tick-sched.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 749ec2a583de..be2e5d772d50 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
> ktime_t now)
>  {
>   update_ts_time_stats(smp_processor_id(), ts, now, NULL);
>   ts->idle_active = 0;
> + ts->idle_exittime = now;
> 
>   sched_clock_idle_wakeup_event();
>  }
> @@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct 
> tick_sched *ts, ktime_t now)
>* Cancel the scheduled timer and restore the tick
>*/
>   ts->tick_stopped  = 0;
> - ts->idle_exittime = now;
> 
>   tick_nohz_restart(ts, now);
>  }

Hi,

I've edited and queued on top of latest changes, see below. I'll post it after
the merge window.

---
From: Yunfeng Ye 
Date: Wed, 10 Feb 2021 00:08:54 +0100
Subject: [PATCH] tick/nohz: Update idle_exittime on actual idle exit

The idle_exittime field of tick_sched is used to record the time when
the idle state was left. but currently the idle_exittime is updated in
the function tick_nohz_restart_sched_tick(), which is not always in idle
state when nohz_full is configured:

  tick_irq_exit
tick_nohz_irq_exit
  tick_nohz_full_update_tick
tick_nohz_restart_sched_tick
  ts->idle_exittime = now;

It's thus overwritten by mistake on nohz_full tick restart. Move the
update to the appropriate idle exit path instead.

Signed-off-by: Yunfeng Ye 
Signed-off-by: Frederic Weisbecker 
---
 kernel/time/tick-sched.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 79796286a4ba..2907c762a8fe 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -918,8 +918,6 @@ static void tick_nohz_restart_sched_tick(struct tick_sched 
*ts, ktime_t now)
 * Cancel the scheduled timer and restore the tick
 */
ts->tick_stopped  = 0;
-   ts->idle_exittime = now;
-
tick_nohz_restart(ts, now);
 }
 
@@ -1231,6 +1229,7 @@ static void tick_nohz_idle_update_tick(struct tick_sched 
*ts, ktime_t now)
else
tick_nohz_restart_sched_tick(ts, now);
 
+   ts->idle_exittime = now;
tick_nohz_account_idle_ticks(ts);
 }
 
-- 
2.25.1

Re: [PATCH] tick/nohz: Make the idle_exittime update correctly

2020-12-17 Thread Yunfeng Ye 



On 2020/12/17 21:59, Frederic Weisbecker wrote:
> On Thu, Dec 17, 2020 at 02:51:58PM +0800, Yunfeng Ye wrote:
>>
>>
>> On 2020/12/15 22:47, Frederic Weisbecker wrote:
>>> On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote:
 The idle_exittime field of tick_sched is used to record the time when
 the idle state was left. but currently the idle_exittime is updated in
 the function tick_nohz_restart_sched_tick(), which is not always in idle
 state when nohz_full is configured.

   tick_irq_exit
 tick_nohz_irq_exit
   tick_nohz_full_update_tick
 tick_nohz_restart_sched_tick
   ts->idle_exittime = now;

 So move to tick_nohz_stop_idle() to make the idle_exittime update
 correctly.

 Signed-off-by: Yunfeng Ye 
 ---
  kernel/time/tick-sched.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

 diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
 index 749ec2a583de..be2e5d772d50 100644
 --- a/kernel/time/tick-sched.c
 +++ b/kernel/time/tick-sched.c
 @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
 ktime_t now)
  {
update_ts_time_stats(smp_processor_id(), ts, now, NULL);
ts->idle_active = 0;
 +  ts->idle_exittime = now;
>>>
>>> This changes a bit the meaning of idle_exittime then since this is also 
>>> called
>>> from idle interrupt entry.
>>>
>>> __tick_nohz_idle_restart_tick() would be a better place.
>>>
>> So is it necessary to modify the comment "@idle_exittime:  Time when the 
>> idle state was left" ?
>>
>> On the other hand, if the patch "nohz: Update tick instead of restarting 
>> tick in tick_nohz_idle_exit()"
>> (https://www.spinics.net/lists/kernel/msg3747039.html ) applied, 
>> __tick_nohz_idle_restart_tick will not
>> be called always, So is it put here also a better place?
> 
> Right but I need to re-order some code before. That's ok, I'll integrate this
> patch inside the changes.
> 
Ok, thanks.

> Thanks.
> .
>

Re: [PATCH] tick/nohz: Make the idle_exittime update correctly

2020-12-17 Thread Frederic Weisbecker 
On Thu, Dec 17, 2020 at 02:51:58PM +0800, Yunfeng Ye wrote:
> 
> 
> On 2020/12/15 22:47, Frederic Weisbecker wrote:
> > On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote:
> >> The idle_exittime field of tick_sched is used to record the time when
> >> the idle state was left. but currently the idle_exittime is updated in
> >> the function tick_nohz_restart_sched_tick(), which is not always in idle
> >> state when nohz_full is configured.
> >>
> >>   tick_irq_exit
> >> tick_nohz_irq_exit
> >>   tick_nohz_full_update_tick
> >> tick_nohz_restart_sched_tick
> >>   ts->idle_exittime = now;
> >>
> >> So move to tick_nohz_stop_idle() to make the idle_exittime update
> >> correctly.
> >>
> >> Signed-off-by: Yunfeng Ye 
> >> ---
> >>  kernel/time/tick-sched.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> >> index 749ec2a583de..be2e5d772d50 100644
> >> --- a/kernel/time/tick-sched.c
> >> +++ b/kernel/time/tick-sched.c
> >> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
> >> ktime_t now)
> >>  {
> >>update_ts_time_stats(smp_processor_id(), ts, now, NULL);
> >>ts->idle_active = 0;
> >> +  ts->idle_exittime = now;
> > 
> > This changes a bit the meaning of idle_exittime then since this is also 
> > called
> > from idle interrupt entry.
> > 
> > __tick_nohz_idle_restart_tick() would be a better place.
> > 
> So is it necessary to modify the comment "@idle_exittime:  Time when the 
> idle state was left" ?
> 
> On the other hand, if the patch "nohz: Update tick instead of restarting tick 
> in tick_nohz_idle_exit()"
> (https://www.spinics.net/lists/kernel/msg3747039.html ) applied, 
> __tick_nohz_idle_restart_tick will not
> be called always, So is it put here also a better place?

Right but I need to re-order some code before. That's ok, I'll integrate this
patch inside the changes.

Thanks.

Re: [PATCH] tick/nohz: Make the idle_exittime update correctly

2020-12-16 Thread Yunfeng Ye 



On 2020/12/15 22:47, Frederic Weisbecker wrote:
> On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote:
>> The idle_exittime field of tick_sched is used to record the time when
>> the idle state was left. but currently the idle_exittime is updated in
>> the function tick_nohz_restart_sched_tick(), which is not always in idle
>> state when nohz_full is configured.
>>
>>   tick_irq_exit
>> tick_nohz_irq_exit
>>   tick_nohz_full_update_tick
>> tick_nohz_restart_sched_tick
>>   ts->idle_exittime = now;
>>
>> So move to tick_nohz_stop_idle() to make the idle_exittime update
>> correctly.
>>
>> Signed-off-by: Yunfeng Ye 
>> ---
>>  kernel/time/tick-sched.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>> index 749ec2a583de..be2e5d772d50 100644
>> --- a/kernel/time/tick-sched.c
>> +++ b/kernel/time/tick-sched.c
>> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
>> ktime_t now)
>>  {
>>  update_ts_time_stats(smp_processor_id(), ts, now, NULL);
>>  ts->idle_active = 0;
>> +ts->idle_exittime = now;
> 
> This changes a bit the meaning of idle_exittime then since this is also called
> from idle interrupt entry.
> 
> __tick_nohz_idle_restart_tick() would be a better place.
> 
So is it necessary to modify the comment "@idle_exittime:  Time when the 
idle state was left" ?

On the other hand, if the patch "nohz: Update tick instead of restarting tick 
in tick_nohz_idle_exit()"
(https://www.spinics.net/lists/kernel/msg3747039.html ) applied, 
__tick_nohz_idle_restart_tick will not
be called always, So is it put here also a better place?

Thanks.

> Thanks.
> 
>>
>>  sched_clock_idle_wakeup_event();
>>  }
>> @@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct 
>> tick_sched *ts, ktime_t now)
>>   * Cancel the scheduled timer and restore the tick
>>   */
>>  ts->tick_stopped  = 0;
>> -ts->idle_exittime = now;
>>
>>  tick_nohz_restart(ts, now);
>>  }
>> -- 
>> 2.18.4
>>
> .
>

Re: [PATCH] tick/nohz: Make the idle_exittime update correctly

2020-12-15 Thread Frederic Weisbecker 
On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote:
> The idle_exittime field of tick_sched is used to record the time when
> the idle state was left. but currently the idle_exittime is updated in
> the function tick_nohz_restart_sched_tick(), which is not always in idle
> state when nohz_full is configured.
> 
>   tick_irq_exit
> tick_nohz_irq_exit
>   tick_nohz_full_update_tick
> tick_nohz_restart_sched_tick
>   ts->idle_exittime = now;
> 
> So move to tick_nohz_stop_idle() to make the idle_exittime update
> correctly.
> 
> Signed-off-by: Yunfeng Ye 
> ---
>  kernel/time/tick-sched.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 749ec2a583de..be2e5d772d50 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
> ktime_t now)
>  {
>   update_ts_time_stats(smp_processor_id(), ts, now, NULL);
>   ts->idle_active = 0;
> + ts->idle_exittime = now;

This changes a bit the meaning of idle_exittime then since this is also called
from idle interrupt entry.

__tick_nohz_idle_restart_tick() would be a better place.

Thanks.

> 
>   sched_clock_idle_wakeup_event();
>  }
> @@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct 
> tick_sched *ts, ktime_t now)
>* Cancel the scheduled timer and restore the tick
>*/
>   ts->tick_stopped  = 0;
> - ts->idle_exittime = now;
> 
>   tick_nohz_restart(ts, now);
>  }
> -- 
> 2.18.4
>