From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [git pull] scheduler fix
Date: Thu, 08 Jan 2009 08:50:53 +0100 [thread overview]
Message-ID: <1231401053.11687.386.camel@twins> (raw)
In-Reply-To: <alpine.LFD.2.00.0901071543550.3057@localhost.localdomain>
On Wed, 2009-01-07 at 15:47 -0800, Linus Torvalds wrote:
>
> On Wed, 7 Jan 2009, Ingo Molnar wrote:
> > + /*
> > + * Should not call ttwu while holding a rq->lock
> > + */
> > + spin_unlock(&this_rq->lock);
> > if (active_balance)
> > wake_up_process(busiest->migration_thread);
> > + spin_lock(&this_rq->lock);
>
> Btw, this isn't the first time we've wanted to do a wakeup while
> potentially locked.
>
> Is there any way to perhaps go a "wake_up_gentle()" that doesn't need the
> lock, and just basically does a potentially delayed wakeup by just
> scheduling it asynchronously.
>
> That would have solved all those nasty printk issues too. These kinds of
> things don't need the strict "wake up NOW" behaviour - they are more of a
> "kick the dang thing and make sure it wakes up in some timely manner".
Right -- so the printk thing was solved by polling some state from the
timer tick, we could make that into a list, but then you'd have to worry
about memory allocation for list elements failing etc.
Same story as generic smp function call, we could do this using a self
(or remote) IPI, but you'd still have the memory allocation issue -- and
would need to make self-IPI work on !SMP.
I'll ponder the issue a bit more, but I'm not directly seeing anything
(of course, if it were easy, we'd have done it ages ago ;-)
next prev parent reply other threads:[~2009-01-08 7:51 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-07 22:26 [git pull] scheduler fix Ingo Molnar
2009-01-07 23:47 ` Linus Torvalds
2009-01-08 7:50 ` Peter Zijlstra [this message]
-- strict thread matches above, loose matches on Subject: below --
2023-10-01 8:43 [GIT PULL] " Ingo Molnar
2023-10-01 17:08 ` pr-tracker-bot
2023-09-22 10:26 Ingo Molnar
2023-09-22 20:19 ` pr-tracker-bot
2021-06-24 7:06 Ingo Molnar
2021-06-24 16:34 ` pr-tracker-bot
2020-12-27 9:16 Ingo Molnar
2020-12-27 17:27 ` pr-tracker-bot
2020-03-02 7:51 Ingo Molnar
2020-03-03 23:35 ` pr-tracker-bot
2019-12-17 11:54 Ingo Molnar
2019-12-17 19:20 ` pr-tracker-bot
2019-07-14 10:19 Ingo Molnar
2019-07-14 18:45 ` pr-tracker-bot
2019-05-05 11:02 Ingo Molnar
2019-05-05 22:10 ` pr-tracker-bot
2019-04-27 14:39 Ingo Molnar
2019-04-27 18:45 ` pr-tracker-bot
2019-04-12 13:08 Ingo Molnar
2019-04-13 4:05 ` pr-tracker-bot
2018-12-31 14:58 Ingo Molnar
2018-12-31 18:05 ` pr-tracker-bot
2018-11-17 10:57 Ingo Molnar
2018-11-18 20:05 ` pr-tracker-bot
2018-10-11 9:12 Ingo Molnar
2018-10-11 12:32 ` Greg Kroah-Hartman
2018-10-11 9:02 Ingo Molnar
2018-01-17 15:34 Ingo Molnar
2017-10-27 19:16 Ingo Molnar
2016-12-07 18:48 Ingo Molnar
2016-10-28 8:35 Ingo Molnar
2016-10-19 15:52 Ingo Molnar
2016-10-18 11:17 Ingo Molnar
2016-09-13 18:17 Ingo Molnar
2016-07-14 18:56 Ingo Molnar
2016-05-13 18:54 Ingo Molnar
2016-05-06 11:31 Ingo Molnar
2015-07-18 2:56 Ingo Molnar
2015-03-28 13:45 Ingo Molnar
2014-01-15 18:19 Ingo Molnar
2013-09-28 18:08 Ingo Molnar
2013-09-12 12:58 Ingo Molnar
2012-05-17 8:46 Ingo Molnar
2012-03-02 10:57 Ingo Molnar
2012-02-27 10:29 Ingo Molnar
2011-04-07 17:38 Ingo Molnar
2011-03-18 13:52 Ingo Molnar
2011-03-10 8:01 Ingo Molnar
2011-01-24 13:07 Ingo Molnar
2010-04-08 15:38 Ingo Molnar
2010-04-08 15:42 ` Linus Torvalds
2010-04-08 16:03 ` Andreas Schwab
2010-04-08 18:26 ` Ingo Molnar
2010-04-08 18:36 ` Linus Torvalds
2010-04-08 18:52 ` Ingo Molnar
2009-12-23 16:03 Ingo Molnar
2009-10-08 19:01 Ingo Molnar
2009-05-05 9:35 Ingo Molnar
2009-02-17 16:40 [git pull] " Ingo Molnar
2009-02-04 19:18 Ingo Molnar
2008-12-04 19:41 Ingo Molnar
2008-04-14 15:07 Ingo Molnar
2008-01-22 10:33 Ingo Molnar
2007-10-29 20:39 [git pull] scheduler fixes Ingo Molnar
2007-10-29 23:34 ` [git pull] scheduler fix Ingo Molnar
2007-10-30 10:15 ` Guillaume Chazarain
2007-11-01 8:39 ` Ingo Molnar
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