From: Xuewen Yan <[email protected]>
Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following:
uc_rq_max = rq->uclamp[UCLAMP_MAX].value;
uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX);
uclamp_max = max{uc_rq_max, uc_eff_max};
Consider the following scenario:
(1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX;
(2)the p's uc_eff_max < uc_rq_max.
The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable.
The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX.
Inserts whether the rq is idle in the uclamp_rq_util_with().
Signed-off-by: Xuewen Yan <[email protected]>
---
kernel/sched/sched.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a189bec13729..0feef6af89f2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
if (p) {
min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
- max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
+ if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
+ max_util = uclamp_eff_value(p, UCLAMP_MAX);
+ else
+ max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
}
/*
--
2.25.1
+cc Qais, Quentin
Hi Dietmar,
The patch has been around for a long time, and I think it makes sense for EAS.
Do you have any suggestions or comments?
Thanks!
xuewen
On Fri, Jun 18, 2021 at 3:24 PM Xuewen Yan <[email protected]> wrote:
>
> From: Xuewen Yan <[email protected]>
>
> Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following:
> uc_rq_max = rq->uclamp[UCLAMP_MAX].value;
> uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX);
> uclamp_max = max{uc_rq_max, uc_eff_max};
>
> Consider the following scenario:
> (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX;
> (2)the p's uc_eff_max < uc_rq_max.
>
> The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable.
>
> The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX.
>
> Inserts whether the rq is idle in the uclamp_rq_util_with().
>
> Signed-off-by: Xuewen Yan <[email protected]>
> ---
> kernel/sched/sched.h | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index a189bec13729..0feef6af89f2 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
>
> if (p) {
> min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
> - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
> + max_util = uclamp_eff_value(p, UCLAMP_MAX);
> + else
> + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> }
>
> /*
> --
> 2.25.1
>
+Cc Patrick's current address
On 18/06/21 15:23, Xuewen Yan wrote:
> From: Xuewen Yan <[email protected]>
>
> Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following:
> uc_rq_max = rq->uclamp[UCLAMP_MAX].value;
> uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX);
> uclamp_max = max{uc_rq_max, uc_eff_max};
>
> Consider the following scenario:
> (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX;
> (2)the p's uc_eff_max < uc_rq_max.
>
> The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable.
>
> The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX.
>
> Inserts whether the rq is idle in the uclamp_rq_util_with().
>
> Signed-off-by: Xuewen Yan <[email protected]>
> ---
> kernel/sched/sched.h | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index a189bec13729..0feef6af89f2 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
>
> if (p) {
> min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
> - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
> + max_util = uclamp_eff_value(p, UCLAMP_MAX);
> + else
> + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and
set the rq clamp as the task's via uclamp_idle_reset().
Does this want a
Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()")
?
Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max
- and I'm pretty sure the same applies to the rq min. What about something like:
---
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 6510f0a46789..a2c6f6ae6392 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2833,23 +2833,27 @@ static __always_inline
unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
struct task_struct *p)
{
- unsigned long min_util;
- unsigned long max_util;
+ unsigned long min_util = 0;
+ unsigned long max_util = 0;
if (!static_branch_likely(&sched_uclamp_used))
return util;
- min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
- max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
-
if (p) {
- min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
+ min_util = uclamp_eff_value(p, UCLAMP_MIN);
+ max_util = uclamp_eff_value(p, UCLAMP_MAX);
+
+ /*
+ * Ignore last runnable task's max clamp, as this task will
+ * reset it. Similarly, no need to read the rq's min clamp.
+ */
if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
- max_util = uclamp_eff_value(p, UCLAMP_MAX);
- else
- max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
+ goto out;
}
+ min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
+ max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
+out:
/*
* Since CPU's {min,max}_util clamps are MAX aggregated considering
* RUNNABLE tasks with _different_ clamps, we can end up with an
On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider
<[email protected]> wrote:
>
>
> +Cc Patrick's current address
>
> On 18/06/21 15:23, Xuewen Yan wrote:
> > From: Xuewen Yan <[email protected]>
> >
> > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following:
> > uc_rq_max = rq->uclamp[UCLAMP_MAX].value;
> > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX);
> > uclamp_max = max{uc_rq_max, uc_eff_max};
> >
> > Consider the following scenario:
> > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX;
> > (2)the p's uc_eff_max < uc_rq_max.
> >
> > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable.
> >
> > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX.
> >
> > Inserts whether the rq is idle in the uclamp_rq_util_with().
> >
> > Signed-off-by: Xuewen Yan <[email protected]>
> > ---
> > kernel/sched/sched.h | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> > index a189bec13729..0feef6af89f2 100644
> > --- a/kernel/sched/sched.h
> > +++ b/kernel/sched/sched.h
> > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
> >
> > if (p) {
> > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
> > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
> > + max_util = uclamp_eff_value(p, UCLAMP_MAX);
> > + else
> > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
>
> That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and
> set the rq clamp as the task's via uclamp_idle_reset().
>
> Does this want a
>
> Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()")
>
> ?
Yes，add it.
>
> Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max
> - and I'm pretty sure the same applies to the rq min. What about something like:
Good idea, I'll try it in V2.
>
> ---
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 6510f0a46789..a2c6f6ae6392 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -2833,23 +2833,27 @@ static __always_inline
> unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
> struct task_struct *p)
> {
> - unsigned long min_util;
> - unsigned long max_util;
> + unsigned long min_util = 0;
> + unsigned long max_util = 0;
>
> if (!static_branch_likely(&sched_uclamp_used))
> return util;
>
> - min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
> - max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
> -
> if (p) {
> - min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
> + min_util = uclamp_eff_value(p, UCLAMP_MIN);
> + max_util = uclamp_eff_value(p, UCLAMP_MAX);
> +
> + /*
> + * Ignore last runnable task's max clamp, as this task will
> + * reset it. Similarly, no need to read the rq's min clamp.
> + */
> if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
> - max_util = uclamp_eff_value(p, UCLAMP_MAX);
> - else
> - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> + goto out;
> }
>
> + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
> + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
Is it necessary to use max_t here? although it is not the main problem...
> +out:
> /*
> * Since CPU's {min,max}_util clamps are MAX aggregated considering
> * RUNNABLE tasks with _different_ clamps, we can end up with an
Thanks!
xuewen
On 30/06/21 09:24, Xuewen Yan wrote:
> On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider
> <[email protected]> wrote:
>> + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
>> + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
>
> Is it necessary to use max_t here? although it is not the main problem...
>
I got comparison warnings when using a regular max() - the RQ clamp values
are unsigned int, whereas the local variable is unsigned long.
>> +out:
>> /*
>> * Since CPU's {min,max}_util clamps are MAX aggregated considering
>> * RUNNABLE tasks with _different_ clamps, we can end up with an
>
> Thanks!
> xuewen
On Wed, Jun 30, 2021 at 7:31 PM Valentin Schneider
<[email protected]> wrote:
>
> On 30/06/21 09:24, Xuewen Yan wrote:
> > On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider
> > <[email protected]> wrote:
> >> + min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
> >> + max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
> >
> > Is it necessary to use max_t here? although it is not the main problem...
> >
>
> I got comparison warnings when using a regular max() - the RQ clamp values
> are unsigned int, whereas the local variable is unsigned long.
Yes，I miss the rq clamp value's type.
Thanks!
xuewen
Thanks for the CC.
On 06/30/21 09:24, Xuewen Yan wrote:
> On Tue, Jun 29, 2021 at 9:50 PM Valentin Schneider
> <[email protected]> wrote:
> >
> >
> > +Cc Patrick's current address
> >
> > On 18/06/21 15:23, Xuewen Yan wrote:
> > > From: Xuewen Yan <[email protected]>
> > >
> > > Now in uclamp_rq_util_with(), when the task != NULL, the uclamp_max as following:
> > > uc_rq_max = rq->uclamp[UCLAMP_MAX].value;
> > > uc_eff_max = uclamp_eff_value(p, UCLAMP_MAX);
> > > uclamp_max = max{uc_rq_max, uc_eff_max};
> > >
> > > Consider the following scenario:
> > > (1)the rq is idle, the uc_rq_max is last task's UCLAMP_MAX;
> > > (2)the p's uc_eff_max < uc_rq_max.
> > >
> > > The result is the uclamp_max = uc_rq_max instead of uc_eff_max, it is unreasonable.
> > >
> > > The scenario often happens in find_energy_efficient_cpu(), when the task has smaller UCLAMP_MAX.
> > >
> > > Inserts whether the rq is idle in the uclamp_rq_util_with().
> > >
> > > Signed-off-by: Xuewen Yan <[email protected]>
> > > ---
> > > kernel/sched/sched.h | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> > > index a189bec13729..0feef6af89f2 100644
> > > --- a/kernel/sched/sched.h
> > > +++ b/kernel/sched/sched.h
> > > @@ -2550,7 +2550,10 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
> > >
> > > if (p) {
> > > min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
> > > - max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> > > + if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
> > > + max_util = uclamp_eff_value(p, UCLAMP_MAX);
> > > + else
> > > + max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
> >
> > That makes sense to me - enqueuing the task will lift UCLAMP_FLAG_IDLE and
> > set the rq clamp as the task's via uclamp_idle_reset().
> >
> > Does this want a
> >
> > Fixes: 9d20ad7dfc9a ("sched/uclamp: Add uclamp_util_with()")
> >
> > ?
>
> Yes，add it.
+1
>
> >
> > Also, when we have UCLAMP_FLAG_IDLE, we don't even need to read the rq max
> > - and I'm pretty sure the same applies to the rq min. What about something like:
uclamp_min is fine since it defaults to 0. But the suggested improvement looks
good to me.
Thanks
--
Qais Yousef