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From: Ionela Voinescu <ionela.voinescu@arm.com>
To: Quentin Perret <qperret@google.com>
Cc: mingo@redhat.com, peterz@infradead.org,
	vincent.guittot@linaro.org, catalin.marinas@arm.com,
	will@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org,
	dietmar.eggemann@arm.com, valentin.schneider@arm.com,
	linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/3] condition EAS enablement on FI support
Date: Thu, 24 Sep 2020 17:08:46 +0100	[thread overview]
Message-ID: <20200924160846.GB17927@arm.com> (raw)
In-Reply-To: <20200924133727.GB3920949@google.com>

On Thursday 24 Sep 2020 at 14:37:27 (+0100), Quentin Perret wrote:
> On Thursday 24 Sep 2020 at 13:39:34 (+0100), Ionela Voinescu wrote:
> > Given the maturity gained by cpufreq-based Frequency Invariance (FI)
> > support following the patches at [1], this series conditions Energy
> > Aware Scheduling (EAS) enablement on a frequency invariant system.
> > 
> > Currently, EAS can be enabled on a system without FI support, leading
> > to incorrect (energy-wise) task placements. As no warning is emitted,
> > it could take some debugging effort to track the behavior back to the
> > lack of FI support; this series changes that by disabling EAS
> > (and advertising it) when FI support is missing.
> > 
> > The series is structured as follows:
> >  - 1/3 - create function that can rebuild the scheduling and EAS'
> >    performance domains if EAS' initial conditions change
> >  - 2/3 - condition EAS enablement on FI support
> >  - 3/3 - arm64: rebuild scheduling and performance domains in the
> >          case of late, counter-driven FI initialisation.
> 
> I'm still reading through this, but shouldn't patch 2 and 3 be swapped?
> Otherwise we have a weird state at patch 2 where EAS will fail to start
> (IIUC), which might not be ideal for bisection.
> 
> Thoughts?

I probably invented myself reasons for not doing it, like: without 2/3,
3/3 does not make any sense having and the scenario at 3/3 is currently
unlikely.

But it would definitely make it safer, so I'll change the order.

Thanks,
Ionela.

> 
> Cheers,
> Quentin

WARNING: multiple messages have this Message-ID (diff)
From: Ionela Voinescu <ionela.voinescu@arm.com>
To: Quentin Perret <qperret@google.com>
Cc: vincent.guittot@linaro.org, linux-pm@vger.kernel.org,
	peterz@infradead.org, catalin.marinas@arm.com, rjw@rjwysocki.net,
	linux-kernel@vger.kernel.org, valentin.schneider@arm.com,
	mingo@redhat.com, viresh.kumar@linaro.org, will@kernel.org,
	dietmar.eggemann@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] condition EAS enablement on FI support
Date: Thu, 24 Sep 2020 17:08:46 +0100	[thread overview]
Message-ID: <20200924160846.GB17927@arm.com> (raw)
In-Reply-To: <20200924133727.GB3920949@google.com>

On Thursday 24 Sep 2020 at 14:37:27 (+0100), Quentin Perret wrote:
> On Thursday 24 Sep 2020 at 13:39:34 (+0100), Ionela Voinescu wrote:
> > Given the maturity gained by cpufreq-based Frequency Invariance (FI)
> > support following the patches at [1], this series conditions Energy
> > Aware Scheduling (EAS) enablement on a frequency invariant system.
> > 
> > Currently, EAS can be enabled on a system without FI support, leading
> > to incorrect (energy-wise) task placements. As no warning is emitted,
> > it could take some debugging effort to track the behavior back to the
> > lack of FI support; this series changes that by disabling EAS
> > (and advertising it) when FI support is missing.
> > 
> > The series is structured as follows:
> >  - 1/3 - create function that can rebuild the scheduling and EAS'
> >    performance domains if EAS' initial conditions change
> >  - 2/3 - condition EAS enablement on FI support
> >  - 3/3 - arm64: rebuild scheduling and performance domains in the
> >          case of late, counter-driven FI initialisation.
> 
> I'm still reading through this, but shouldn't patch 2 and 3 be swapped?
> Otherwise we have a weird state at patch 2 where EAS will fail to start
> (IIUC), which might not be ideal for bisection.
> 
> Thoughts?

I probably invented myself reasons for not doing it, like: without 2/3,
3/3 does not make any sense having and the scenario at 3/3 is currently
unlikely.

But it would definitely make it safer, so I'll change the order.

Thanks,
Ionela.

> 
> Cheers,
> Quentin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2020-09-24 16:08 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-24 12:39 [PATCH 0/3] condition EAS enablement on FI support Ionela Voinescu
2020-09-24 12:39 ` Ionela Voinescu
2020-09-24 12:39 ` [PATCH 1/3] sched/topology,schedutil: wrap sched domains rebuild Ionela Voinescu
2020-09-24 12:39   ` Ionela Voinescu
2020-09-24 13:34   ` Quentin Perret
2020-09-24 13:34     ` Quentin Perret
2020-09-24 16:07     ` Ionela Voinescu
2020-09-24 16:07       ` Ionela Voinescu
2020-09-24 12:39 ` [PATCH 2/3] sched/topology: condition EAS enablement on FIE support Ionela Voinescu
2020-09-24 12:39   ` Ionela Voinescu
2020-09-24 12:39 ` [PATCH 3/3] arm64: rebuild sched domains on invariance status changes Ionela Voinescu
2020-09-24 12:39   ` Ionela Voinescu
2020-09-24 13:39   ` Quentin Perret
2020-09-24 13:39     ` Quentin Perret
2020-09-24 16:10     ` Ionela Voinescu
2020-09-24 16:10       ` Ionela Voinescu
2020-09-25 13:59       ` Quentin Perret
2020-09-25 13:59         ` Quentin Perret
2020-09-28 11:55         ` Dietmar Eggemann
2020-09-28 11:55           ` Dietmar Eggemann
2020-09-28 14:23           ` Ionela Voinescu
2020-09-28 14:23             ` Ionela Voinescu
2020-09-24 13:37 ` [PATCH 0/3] condition EAS enablement on FI support Quentin Perret
2020-09-24 13:37   ` Quentin Perret
2020-09-24 16:08   ` Ionela Voinescu [this message]
2020-09-24 16:08     ` Ionela Voinescu

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