linux-kernel - Re: [RFC PATCH v1 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection

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Date:   Thu, 06 Jul 2017 23:08:12 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Juri Lelli <juri.lelli@....com>
Cc:     peterz@...radead.org, mingo@...hat.com, viresh.kumar@...aro.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        tglx@...utronix.de, vincent.guittot@...aro.org,
        rostedt@...dmis.org, luca.abeni@...tannapisa.it,
        claudio@...dence.eu.com, tommaso.cucinotta@...tannapisa.it,
        bristot@...hat.com, mathieu.poirier@...aro.org, tkjos@...roid.com,
        joelaf@...gle.com, andresoportus@...gle.com,
        morten.rasmussen@....com, dietmar.eggemann@....com,
        patrick.bellasi@....com
Subject: Re: [RFC PATCH v1 0/8] SCHED_DEADLINE freq/cpu invariance and OPP selection

On Wednesday, July 05, 2017 09:58:57 AM Juri Lelli wrote:
> Hi,
> 
> v1 of the RFC set implementing frequency/cpu invariance and OPP selection for
> SCHED_DEADLINE [1]. The set is based on tip/sched/core as of today
> (72298e5c92c5), which now already includes Luca's "CPU reclaiming for
> SCHED_DEADLINE".
> 
> Thanks a lot for reviewing RFCv0!
> 
> Patches high level description:
> 
>  o [01-02]/08 add the necessary links to start accounting DEADLINE contribution
>               to OPP selection 
>  o 03/08      it's a temporary solution to make possible (on ARM) to change
>               frequency for DEADLINE tasks (that would possibly delay the SCHED_FIFO
>               worker kthread); proper solution would be to be able to issue frequency
>               transition from an atomic ctx
>  o [04-05]/08 it's a schedutil change that copes with the fact that DEADLINE
>               doesn't require periodic OPP selection triggering point
>  o [06-07]/08 make arch_scale_{freq,cpu}_capacity() function available on !CONFIG_SMP
>               configurations too
>  o 08/08      implements frequency/cpu invariance for tasks' reservation
>               parameters; which basically means that we implement GRUB-PA [2]
> 
> Changes w.r.t. RFCv0:
> 
>  - rebase on tip/sched/core
>  - make use of BW_SHIFT for calculations (Peter)
>  - added a comment about guaranteed/requested frequency (Peter)
>  - use a high bit for sched_flags SCHED_FLAG_SPECIAL hack; don't expose it to
>    userspace and add comments (Peter)
>  - refactor aggregation of utilization from scheduling classes
> 
> Please have a look. Feedback and comments are, as usual, more than welcome.
> 
> In case you would like to test this out:
> 
>  git://linux-arm.org/linux-jl.git upstream/deadline/freq-rfc-v1
> 
> Best,
> 
> - Juri
> 
> 
> Juri Lelli (8):
>   sched/cpufreq_schedutil: make use of DEADLINE utilization signal
>   sched/deadline: move cpu frequency selection triggering points
>   sched/cpufreq_schedutil: make worker kthread be SCHED_DEADLINE
>   sched/cpufreq_schedutil: split utilization signals
>   sched/cpufreq_schedutil: always consider all CPUs when deciding next
>     freq
>   sched/sched.h: remove sd arch_scale_freq_capacity parameter
>   sched/sched.h: move arch_scale_{freq,cpu}_capacity outside CONFIG_SMP
>   sched/deadline: make bandwidth enforcement scale-invariant
> 
>  include/linux/sched.h            |  1 +
>  include/linux/sched/cpufreq.h    |  2 --
>  include/linux/sched/topology.h   | 12 +++----
>  kernel/sched/core.c              | 15 ++++++--
>  kernel/sched/cpufreq_schedutil.c | 77 ++++++++++++++++++++++++++--------------
>  kernel/sched/deadline.c          | 46 ++++++++++++++++++++----
>  kernel/sched/fair.c              |  4 +--
>  kernel/sched/sched.h             | 51 +++++++++++++++++++-------
>  8 files changed, 149 insertions(+), 59 deletions(-)

The schedutil changes in this series look OK to me, so please feel free to add

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

to these patches.

Thanks,
Rafael