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 <[email protected]>
---
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);
}
--
2.18.4
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 <[email protected]>
---
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);
}
--
2.18.4
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 <[email protected]>
> ---
> 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
>
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 <[email protected]>
>> ---
>> 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
>>
> .
>
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 <[email protected]>
> >> ---
> >> 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.
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 <[email protected]>
>>>> ---
>>>> 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.
> .
>
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 <[email protected]>
> ---
> 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 <[email protected]>
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 <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
---
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