From: Oleg Nesterov <oleg@redhat.com>
To: Colin Cross <ccross@android.com>
Cc: "Linux PM list" <linux-pm@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
"Arve Hjønnevåg" <arve@android.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Serge Hallyn" <serge.hallyn@canonical.com>
Subject: Re: [PATCH 09/10] sigtimedwait: use freezable blocking call
Date: Tue, 30 Apr 2013 19:00:27 +0200 [thread overview]
Message-ID: <20130430170027.GA28380@redhat.com> (raw)
In-Reply-To: <CAMbhsRTABgbWgFca03nVWVmVeK5Ci9BPon-zQwanM16LrN=fog@mail.gmail.com>
On 04/30, Colin Cross wrote:
> On Tue, Apr 30, 2013 at 9:38 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> > On 04/29, Colin Cross wrote:
> >>
> >> Avoid waking up every thread sleeping in a sigtimedwait call during
> >> suspend and resume by calling a freezable blocking call.
> >
> > This doesn't explain why do want this change...
> >
> > OK, probably to avoid -EAGAIN from sigtimedwait() if the freezer wakes
> > up the caller.
>
> See http://marc.info/?l=linux-pm&m=136727197819593&w=2 for the full
> justification. I will include a fuller description of the reason for
> this patch in the next version.
Yes, thanks, I already realized what are you trying to do.
> > The task will be interrupted anyway and the syscall will return
> > -EAGAIN, this only changes the time when try_to_freeze() is called.
> >
> > For what? The task will call do_signal/try_to_freeze really "soon".
>
> See http://marc.info/?l=linux-pm&m=136727204919622&w=2, which removes
> the wakeup sent to skipped tasks, so schedule_timeout_interruptible()
> will only return if the timeout finishes or another task
Or if freeze_task() was already called.
but I guess you do not care.
Oleg.
next prev parent reply other threads:[~2013-04-30 17:03 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-29 21:45 [PATCH 00/10] optimize freezing tasks by reducing task wakeups Colin Cross
2013-04-29 21:45 ` [PATCH 01/10] freezer: shorten freezer sleep time using exponential backoff Colin Cross
2013-05-02 12:28 ` Pavel Machek
2013-04-29 21:45 ` [PATCH 02/10] freezer: skip waking up tasks with PF_FREEZER_SKIP set Colin Cross
2013-04-29 21:51 ` Tejun Heo
2013-04-29 21:57 ` Tejun Heo
2013-04-29 22:02 ` Colin Cross
2013-04-29 22:08 ` Tejun Heo
2013-04-29 22:16 ` Tejun Heo
2013-04-30 11:48 ` Rafael J. Wysocki
2013-04-30 17:10 ` Oleg Nesterov
2013-04-30 17:15 ` Oleg Nesterov
2013-04-29 21:45 ` [PATCH 03/10] freezer: add new freezable helpers using freezer_do_not_count() Colin Cross
2013-05-02 12:48 ` Pavel Machek
2013-05-02 13:05 ` Oliver Neukum
2013-05-02 13:46 ` Pavel Machek
2013-05-02 17:05 ` Colin Cross
2013-05-03 14:00 ` Pavel Machek
2013-04-29 21:45 ` [PATCH 04/10] binder: use freezable blocking calls Colin Cross
2013-04-29 21:45 ` [PATCH 05/10] epoll: use freezable blocking call Colin Cross
2013-04-29 21:45 ` [PATCH 06/10] select: " Colin Cross
2013-04-29 21:45 ` [PATCH 07/10] futex: " Colin Cross
2013-04-29 22:52 ` Darren Hart
2013-04-29 23:46 ` Colin Cross
2013-05-02 19:52 ` Matt Helsley
2013-04-29 21:45 ` [PATCH 08/10] nanosleep: " Colin Cross
2013-04-29 21:45 ` [PATCH 09/10] sigtimedwait: " Colin Cross
2013-04-30 16:38 ` Oleg Nesterov
2013-04-30 16:56 ` Oleg Nesterov
2013-04-30 16:58 ` Colin Cross
2013-04-30 17:00 ` Oleg Nesterov [this message]
2013-04-29 21:45 ` [PATCH 10/10] af_unix: use freezable blocking calls in read Colin Cross
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