From: Quentin Perret <qperret@google.com>
To: Thara Gopinath <thara.gopinath@linaro.org>
Cc: mingo@redhat.com, peterz@infradead.org, ionela.voinescu@arm.com,
vincent.guittot@linaro.org, rui.zhang@intel.com,
edubezval@gmail.com, linux-kernel@vger.kernel.org,
amit.kachhap@gmail.com, javi.merino@kernel.org,
daniel.lezcano@linaro.org, kernel-team@android.com
Subject: Re: [Patch v3 7/7] sched: thermal: Enable tuning of decay period
Date: Tue, 22 Oct 2019 10:03:34 +0100 [thread overview]
Message-ID: <20191022090334.GA85349@google.com> (raw)
In-Reply-To: <5DAE1D3C.4090008@linaro.org>
Hi Thara,
On Monday 21 Oct 2019 at 17:03:56 (-0400), Thara Gopinath wrote:
> On 10/15/2019 06:14 AM, Quentin Perret wrote:
> > Hi Thara,
> >
> > On Sunday 13 Oct 2019 at 20:58:25 (-0400), Thara Gopinath wrote:
> >> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> >> index 00fcea2..5056c08 100644
> >> --- a/kernel/sysctl.c
> >> +++ b/kernel/sysctl.c
> >> @@ -376,6 +376,13 @@ static struct ctl_table kern_table[] = {
> >> .mode = 0644,
> >> .proc_handler = proc_dointvec,
> >> },
> >> + {
> >> + .procname = "sched_thermal_decay_coeff",
> >> + .data = &sysctl_sched_thermal_decay_coeff,
> >> + .maxlen = sizeof(unsigned int),
> >> + .mode = 0644,
> >> + .proc_handler = proc_dointvec,
> >
> > Perhaps change this for 'sched_proc_update_handler' with min and max
> > values ? Otherwise userspace is allowed to write nonsensical values
> > here. And since sysctl_sched_thermal_decay_coeff is used to shift, this
> > can lead to an undefined behaviour.
> Will do
> >
> > Also, could we take this sysctl out of SCHED_DEBUG ? I expect this to be
> > used/tuned on production devices where SCHED_DEBUG should theoretically
> > be off.
>
> I will take it out of SCHED_DEBUG. I am wondering if this should be
> a runtime control at all. Because this is a shift this changes the
> accumulating window for the thermal pressure signal. A runtime change
> will not guarantee a clean start of the window. May be I should make
> this a config option.
I'd personally prefer if it wan't a Kconfig option. We'd like to make
Android devices (which are going to use this) work with a Generic Kernel
Image, which means there will be a single config for everyone. But I
expect this knob to be tuned to different values depending on the SoC.
If you really don't want a sysctl, perhaps a cmdline option could work ?
Thanks,
Quentin
next prev parent reply other threads:[~2019-10-22 9:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 0:58 [Patch v3 0/7] Introduce Thermal Pressure Thara Gopinath
2019-10-14 0:58 ` [Patch v3 1/7] sched/pelt.c: Add support to track thermal pressure Thara Gopinath
2019-10-14 13:55 ` Vincent Guittot
2019-10-16 21:15 ` Thara Gopinath
2019-10-14 0:58 ` [Patch v3 2/7] sched: Add infrastructure to store and update instantaneous " Thara Gopinath
2019-10-14 15:50 ` Vincent Guittot
2019-10-16 21:22 ` Thara Gopinath
2019-10-17 8:44 ` Vincent Guittot
2019-10-17 16:40 ` Thara Gopinath
2019-10-18 8:05 ` Vincent Guittot
2019-10-14 0:58 ` [Patch v3 3/7] sched: Initialize per cpu thermal pressure structure Thara Gopinath
2019-10-14 0:58 ` [Patch v3 4/7] sched/fair: Enable CFS periodic tick to update thermal pressure Thara Gopinath
2019-10-14 0:58 ` [Patch v3 5/7] sched/fair: update cpu_capcity to reflect " Thara Gopinath
2019-10-14 0:58 ` [Patch v3 6/7] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping Thara Gopinath
2019-10-14 0:58 ` [Patch v3 7/7] sched: thermal: Enable tuning of decay period Thara Gopinath
2019-10-15 10:14 ` Quentin Perret
2019-10-21 21:03 ` Thara Gopinath
2019-10-22 9:03 ` Quentin Perret [this message]
2019-10-22 20:36 ` Thara Gopinath
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191022090334.GA85349@google.com \
--to=qperret@google.com \
--cc=amit.kachhap@gmail.com \
--cc=daniel.lezcano@linaro.org \
--cc=edubezval@gmail.com \
--cc=ionela.voinescu@arm.com \
--cc=javi.merino@kernel.org \
--cc=kernel-team@android.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rui.zhang@intel.com \
--cc=thara.gopinath@linaro.org \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).