[PATCH] sched/debug: Fix requested task uclamp values shown in procfs

[PATCH] sched/debug: Fix requested task uclamp values shown in procfs

[Pavankumar Kondeti]

The intention of commit 96e74ebf8d59 ("sched/debug: Add task uclamp
values to SCHED_DEBUG procfs") was to print requested and effective
task uclamp values. The requested values printed are read from p->uclamp,
which holds the last effective values. Fix this by printing the values
from p->uclamp_req.

Fixes: 96e74ebf8d59 ("sched/debug: Add task uclamp values to SCHED_DEBUG procfs")
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
---
 kernel/sched/debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index a562df5..239970b 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -948,8 +948,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 	P(se.avg.util_est.enqueued);
 #endif
 #ifdef CONFIG_UCLAMP_TASK
-	__PS("uclamp.min", p->uclamp[UCLAMP_MIN].value);
-	__PS("uclamp.max", p->uclamp[UCLAMP_MAX].value);
+	__PS("uclamp.min", p->uclamp_req[UCLAMP_MIN].value);
+	__PS("uclamp.max", p->uclamp_req[UCLAMP_MAX].value);
 	__PS("effective uclamp.min", uclamp_eff_value(p, UCLAMP_MIN));
 	__PS("effective uclamp.max", uclamp_eff_value(p, UCLAMP_MAX));
 #endif
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

Re: [PATCH] sched/debug: Fix requested task uclamp values shown in procfs

[Valentin Schneider]

On 10/05/20 13:56, Pavankumar Kondeti wrote:
> The intention of commit 96e74ebf8d59 ("sched/debug: Add task uclamp
> values to SCHED_DEBUG procfs") was to print requested and effective
> task uclamp values. The requested values printed are read from p->uclamp,
> which holds the last effective values. Fix this by printing the values
> from p->uclamp_req.
>
> Fixes: 96e74ebf8d59 ("sched/debug: Add task uclamp values to SCHED_DEBUG procfs")
> Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>

Argh, Qais pointed this out to me ~ a week ago, and I left this in my todo
stack. I goofed up, sorry!

As Pavan points out, p->uclamp[foo] is just a cache of uclamp_eff_value(p,
foo) from the last time p was enqueued and runnable - what we are
interested in is indeed comparing this with the *requested* value.

I wanted to send an example along with a patch, I guess that's the kick I
needed!


My setup is a busy loop, its per-task clamps are set to (256, 768) via
sched_setattr(), and it's shoved in a cpu cgroup with uclamp settings of
(50%, 50%)

On the current master (e99332e7b4cd ("gcc-10: mark more functions __init to
avoid section mismatch warnings")), this gives me:

  $ uclamp-get $PID # via sched_getattr()
  uclamp.min=256 uclamp.max=768

  $ cat /proc/$PID/sched | grep uclamp
  uclamp.min                                   :                  256
  uclamp.max                                   :                  512
  effective uclamp.min                         :                  256
  effective uclamp.max                         :                  512

With Pavan's patch, I get:

  $ uclamp-get $PID # via sched_getattr()
  uclamp.min=256 uclamp.max=768

  $ cat /proc/$PID/sched | grep uclamp
  uclamp.min                                   :                  256
  uclamp.max                                   :                  768
  effective uclamp.min                         :                  256
  effective uclamp.max                         :                  512


Minor print nit below, otherwise:
Tested-and-reviewed-by: Valentin Schneider <valentin.schneider@arm.com>

Peter/Ingo, any chance this can go to sched/urgent? I know it's a debug
interface, but I'd rather have it land in a shape that makes sense. Again,
apologies for the goof.

> ---
>  kernel/sched/debug.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index a562df5..239970b 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -948,8 +948,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
>       P(se.avg.util_est.enqueued);
>  #endif
>  #ifdef CONFIG_UCLAMP_TASK
> -	__PS("uclamp.min", p->uclamp[UCLAMP_MIN].value);
> -	__PS("uclamp.max", p->uclamp[UCLAMP_MAX].value);
> +	__PS("uclamp.min", p->uclamp_req[UCLAMP_MIN].value);
> +	__PS("uclamp.max", p->uclamp_req[UCLAMP_MAX].value);

While we're at it, I'd prepend this with "requested".

>       __PS("effective uclamp.min", uclamp_eff_value(p, UCLAMP_MIN));
>       __PS("effective uclamp.max", uclamp_eff_value(p, UCLAMP_MAX));
>  #endif

Re: [PATCH] sched/debug: Fix requested task uclamp values shown in procfs

[Pavan Kondeti]

On Sun, May 10, 2020 at 05:16:28PM +0100, Valentin Schneider wrote:
> 
> On 10/05/20 13:56, Pavankumar Kondeti wrote:
> > The intention of commit 96e74ebf8d59 ("sched/debug: Add task uclamp
> > values to SCHED_DEBUG procfs") was to print requested and effective
> > task uclamp values. The requested values printed are read from p->uclamp,
> > which holds the last effective values. Fix this by printing the values
> > from p->uclamp_req.
> >
> > Fixes: 96e74ebf8d59 ("sched/debug: Add task uclamp values to SCHED_DEBUG procfs")
> > Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
> 
> Argh, Qais pointed this out to me ~ a week ago, and I left this in my todo
> stack. I goofed up, sorry!
> 
> As Pavan points out, p->uclamp[foo] is just a cache of uclamp_eff_value(p,
> foo) from the last time p was enqueued and runnable - what we are
> interested in is indeed comparing this with the *requested* value.
> 
> I wanted to send an example along with a patch, I guess that's the kick I
> needed!
> 
> 
> My setup is a busy loop, its per-task clamps are set to (256, 768) via
> sched_setattr(), and it's shoved in a cpu cgroup with uclamp settings of
> (50%, 50%)
> 
> On the current master (e99332e7b4cd ("gcc-10: mark more functions __init to
> avoid section mismatch warnings")), this gives me:
> 
>   $ uclamp-get $PID # via sched_getattr()
>   uclamp.min=256 uclamp.max=768
> 
>   $ cat /proc/$PID/sched | grep uclamp
>   uclamp.min                                   :                  256
>   uclamp.max                                   :                  512
>   effective uclamp.min                         :                  256
>   effective uclamp.max                         :                  512
> 
> With Pavan's patch, I get:
> 
>   $ uclamp-get $PID # via sched_getattr()
>   uclamp.min=256 uclamp.max=768
> 
>   $ cat /proc/$PID/sched | grep uclamp
>   uclamp.min                                   :                  256
>   uclamp.max                                   :                  768
>   effective uclamp.min                         :                  256
>   effective uclamp.max                         :                  512
> 
> 
> Minor print nit below, otherwise:
> Tested-and-reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
> 
> Peter/Ingo, any chance this can go to sched/urgent? I know it's a debug
> interface, but I'd rather have it land in a shape that makes sense. Again,
> apologies for the goof.
> 
> > ---
> >  kernel/sched/debug.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> > index a562df5..239970b 100644
> > --- a/kernel/sched/debug.c
> > +++ b/kernel/sched/debug.c
> > @@ -948,8 +948,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
> >       P(se.avg.util_est.enqueued);
> >  #endif
> >  #ifdef CONFIG_UCLAMP_TASK
> > -	__PS("uclamp.min", p->uclamp[UCLAMP_MIN].value);
> > -	__PS("uclamp.max", p->uclamp[UCLAMP_MAX].value);
> > +	__PS("uclamp.min", p->uclamp_req[UCLAMP_MIN].value);
> > +	__PS("uclamp.max", p->uclamp_req[UCLAMP_MAX].value);
> 
> While we're at it, I'd prepend this with "requested".
> 
> >       __PS("effective uclamp.min", uclamp_eff_value(p, UCLAMP_MIN));
> >       __PS("effective uclamp.max", uclamp_eff_value(p, UCLAMP_MAX));
> >  #endif

Thanks Valentin for taking a look. I have added "requested" prefix and sent
the patch.

Thanks,
Pavan

-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[tip: sched/urgent] sched/debug: Fix requested task uclamp values shown in procfs

[tip-bot2 for Pavankumar Kondeti]

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     ad32bb41fca67936c0c1d6d0bdd6d3e2e9c5432f
Gitweb:        https://git.kernel.org/tip/ad32bb41fca67936c0c1d6d0bdd6d3e2e9c5432f
Author:        Pavankumar Kondeti <pkondeti@codeaurora.org>
AuthorDate:    Sun, 10 May 2020 18:26:41 +05:30
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 19 May 2020 20:34:10 +02:00

sched/debug: Fix requested task uclamp values shown in procfs

The intention of commit 96e74ebf8d59 ("sched/debug: Add task uclamp
values to SCHED_DEBUG procfs") was to print requested and effective
task uclamp values. The requested values printed are read from p->uclamp,
which holds the last effective values. Fix this by printing the values
from p->uclamp_req.

Fixes: 96e74ebf8d59 ("sched/debug: Add task uclamp values to SCHED_DEBUG procfs")
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/1589115401-26391-1-git-send-email-pkondeti@codeaurora.org
---
 kernel/sched/debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index a562df5..239970b 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -948,8 +948,8 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 	P(se.avg.util_est.enqueued);
 #endif
 #ifdef CONFIG_UCLAMP_TASK
-	__PS("uclamp.min", p->uclamp[UCLAMP_MIN].value);
-	__PS("uclamp.max", p->uclamp[UCLAMP_MAX].value);
+	__PS("uclamp.min", p->uclamp_req[UCLAMP_MIN].value);
+	__PS("uclamp.max", p->uclamp_req[UCLAMP_MAX].value);
 	__PS("effective uclamp.min", uclamp_eff_value(p, UCLAMP_MIN));
 	__PS("effective uclamp.max", uclamp_eff_value(p, UCLAMP_MAX));
 #endif