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From: Joel Fernandes <joel@joelfernandes.org>
To: Hugo Lefeuvre <hle@owl.eu.com>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Greg Hartman" <ghartman@google.com>,
	"Alistair Strachan" <strachan@google.com>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Todd Kjos" <tkjos@android.com>,
	"Martijn Coenen" <maco@android.com>,
	"Christian Brauner" <christian@brauner.io>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] sched/wait: use freezable_schedule when possible
Date: Sat, 2 Feb 2019 13:37:43 -0500	[thread overview]
Message-ID: <20190202183743.GA229953@google.com> (raw)
In-Reply-To: <d9b2ed186ed6fcacaaecd876bb66dca8fa329d8b.1548998323.git.hle@owl.eu.com>

On Fri, Feb 01, 2019 at 06:38:05AM +0100, Hugo Lefeuvre wrote:
> Replace schedule(); try_to_freeze() by freezable_schedule().
> 
> Tasks calling freezable_schedule() set the PF_FREEZER_SKIP flag
> before calling schedule(). Unlike tasks calling schedule();
> try_to_freeze() tasks calling freezable_schedule() are not awaken by
> try_to_freeze_tasks(). Instead they call try_to_freeze() when they
> wake up if the freeze is still underway.
> 
> It is not a problem since sleeping tasks can't do anything which isn't
> allowed for a frozen task while sleeping.
> 
> The result is a potential performance gain during freeze, since less
> tasks have to be awaken.

I'm curious did you try the freezing process and see if pointless wakeups are
reduced?  That would be an added bonus if you did.

Otherwise seems like a nice change. Peter and Rafael, what do you think?

thanks,

 - Joel


  reply	other threads:[~2019-02-02 18:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-01  5:37 [PATCH 0/3] sched/wait, staging/android: simplification and optimization of freeze related code Hugo Lefeuvre
2019-02-01  5:38 ` [PATCH 1/3] sched/wait: use freezable_schedule when possible Hugo Lefeuvre
2019-02-02 18:37   ` Joel Fernandes [this message]
2019-02-06 23:30     ` Hugo Lefeuvre
2019-02-07 15:05       ` Joel Fernandes
2019-02-07 21:40         ` Hugo Lefeuvre
2019-02-07 13:28     ` Hugo Lefeuvre
2019-02-05 16:37   ` Joel Fernandes
2019-02-01  5:38 ` [PATCH 2/3] sched/wait: introduce wait_event_freezable_hrtimeout Hugo Lefeuvre
2019-02-05 16:42   ` Joel Fernandes
2019-02-01  5:39 ` [PATCH 3/3] staging/android: simplify handle_vsoc_cond_wait Hugo Lefeuvre
2019-02-04 15:52   ` Joel Fernandes

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