linux-kernel - Re: [PATCH/RFC] sched: Remove SYSTEM_RUNNING checks from cond

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Date:	Thu, 9 Jul 2009 01:33:31 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	a.p.zijlstra@...llo.nl, oleg@...hat.com, mingo@...e.hu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH/RFC] sched: Remove SYSTEM_RUNNING checks from
 cond_resched*()

On Wed, Jul 08, 2009 at 02:10:24PM -0700, Andrew Morton wrote:
> > On Wed, 8 Jul 2009 09:12:30 -0700 (PDT) Linus Torvalds <torvalds@...ux-foundation.org> wrote:
> > That said, I do agree that maybe SYSTEM_RUNNING isn't the right check. 
> > Testing that the scheduler is initialized may be the more correct one. I 
> > think the SYSTEM_RUNNING one just comes from that being used for other 
> > debug issues.
> 
> Agreed.  system_state is too general.
> 
> If we specifically want to know whether it is safe to call schedule() then
> let's create a global boolean it_is_safe_to_call_schedule and test that,
> rather than testing something which indirectly and unreliably implies "it
> is safe to call schedule".  If that boolean already exists then no-brainer.
> 
> All that being said, I wonder if the netconsole code should be using
> msleep(1) instead.  Spinning on cond_resched() is a bit rude.  But one
> would have to verify that it is safe to call schedule() at this time, and
> for the netconsole caller, this is dubious.

What do you mean by "verify that it is safe"? If it works,
can I assume that it's safe? ;-) It works, fwiw.

Thanks,

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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