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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Juri Lelli <juri.lelli@redhat.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Joel Fernandes <joel@joelfernandes.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Claudio Scordino <claudio@evidence.eu.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Patrick Bellasi <patrick.bellasi@arm.com>,
	Luca Abeni <luca.abeni@santannapisa.it>,
	Joel Fernandes <joelaf@google.com>,
	Linux PM <linux-pm@vger.kernel.org>
Subject: Re: [RFC PATCH] sched/cpufreq/schedutil: handling urgent frequency requests
Date: Wed, 9 May 2018 10:25:19 +0200	[thread overview]
Message-ID: <CAJZ5v0hkeCOybZo4LPpwiE0PG8msCWQkgiHJbpi-6zJHtOQbfg@mail.gmail.com> (raw)
In-Reply-To: <20180509082350.GB1681@localhost.localdomain>

On Wed, May 9, 2018 at 10:23 AM, Juri Lelli <juri.lelli@redhat.com> wrote:
> On 09/05/18 10:05, Rafael J. Wysocki wrote:
>> On Wed, May 9, 2018 at 9:01 AM, Joel Fernandes <joel@joelfernandes.org> wrote:
>> > On Wed, May 09, 2018 at 12:24:49PM +0530, Viresh Kumar wrote:
>> >> On 09-05-18, 08:45, Juri Lelli wrote:
>> >> > On 08/05/18 21:54, Joel Fernandes wrote:
>> >> > Isn't this potentially introducing unneeded irq pressure (and doing the
>> >> > whole wakeup the kthread thing), while the already active kthread could
>> >> > simply handle multiple back-to-back requests before going to sleep?
>> >>
>> >> And then we may need more instances of the work item and need to store
>> >> a different value of next_freq with each work item, as we can't use
>> >> the common one anymore as there would be races around accessing it ?
>> >
>> > Exactly. I think it also doesn't make sense to over write an already
>> > committed request either so better to store them separate (?). After the
>> > "commit", that previous request is done..
>>
>> Why is it?
>>
>> In the non-fast-switch case the "commit" only means queuing up an
>> irq_work.  Which BTW is one of the reasons for having work_in_progress
>> even if your kthread can handle multiple work items in one go.
>>
>> You may try to clear work_in_progress in sugov_irq_work() instead of
>> in sugov_work(), though.
>>
>> BTW, I'm not sure if the comment in sugov_irq_work() still applies.  Juri?
>
> It doesn't anymore. sugov kthreads are now being "ignored". Should have
> remove it with the DL set of changes, sorry about that.

No worries, you can still do that. ;-)

  reply	other threads:[~2018-05-09  8:25 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-07 14:43 Claudio Scordino
2018-05-08  6:54 ` Viresh Kumar
2018-05-08 12:32   ` Claudio Scordino
2018-05-08 20:40     ` Rafael J. Wysocki
2018-05-09  4:54   ` Joel Fernandes
2018-05-09  6:45     ` Juri Lelli
2018-05-09  6:54       ` Viresh Kumar
2018-05-09  7:01         ` Joel Fernandes
2018-05-09  8:05           ` Rafael J. Wysocki
2018-05-09  8:22             ` Joel Fernandes
2018-05-09  8:41               ` Rafael J. Wysocki
2018-05-09  8:23             ` Juri Lelli
2018-05-09  8:25               ` Rafael J. Wysocki [this message]
2018-05-09  8:41                 ` Juri Lelli
2018-05-09  6:55       ` Joel Fernandes
2018-05-09  8:06       ` Joel Fernandes
2018-05-09  8:30         ` Rafael J. Wysocki
2018-05-09  8:40           ` Viresh Kumar
2018-05-09  9:02             ` Joel Fernandes
2018-05-09  9:28               ` Viresh Kumar
2018-05-09 10:34                 ` Joel Fernandes
2018-05-09  8:51           ` Joel Fernandes
2018-05-09  9:06             ` Rafael J. Wysocki
2018-05-09  9:39               ` Joel Fernandes
2018-05-09  9:48                 ` Rafael J. Wysocki

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