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From: Ingo Molnar <mingo@kernel.org>
To: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	kvm@vger.kernel.org, avi@redhat.com, mtosatti@redhat.com,
	yoshikawa.takuya@oss.ntt.co.jp
Subject: Re: [RFC] sched: make callers check lock contention for cond_resched_lock()
Date: Fri, 18 May 2012 09:26:05 +0200	[thread overview]
Message-ID: <20120518072604.GG429@gmail.com> (raw)
In-Reply-To: <20120511070357.9bf8f9b6636a12927f26bfed@gmail.com>


* Takuya Yoshikawa <takuya.yoshikawa@gmail.com> wrote:

> Replaced Ingo's address with kernel.org one,
> 
> On Thu, 03 May 2012 17:47:30 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > On Thu, 2012-05-03 at 22:00 +0900, Takuya Yoshikawa wrote:
> > > But as I could not see why spin_needbreak() was differently
> > > implemented
> > > depending on CONFIG_PREEMPT, I wanted to understand the meaning. 
> > 
> > Its been that way since before voluntary preemption was introduced, so
> > its possible Ingo simply missed that spot and nobody noticed until now.
> > 
> > Ingo, do you have any recollections from back when?
> 
> ping

I'm not sure we had a usable spin_is_contended() back then, nor 
was the !PREEMPT case in my mind really.

( The patch looks ugly though, in 99% of the lines it just does
  something that cond_resched_lock() itself could do. )

Thanks,

	Ingo

  reply	other threads:[~2012-05-18  7:26 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-03  8:12 [RFC] sched: make callers check lock contention for cond_resched_lock() Takuya Yoshikawa
2012-05-03  8:35 ` Peter Zijlstra
2012-05-03 12:22   ` Takuya Yoshikawa
2012-05-03 12:29     ` Peter Zijlstra
2012-05-03 12:47       ` Avi Kivity
2012-05-03 14:11         ` Takuya Yoshikawa
2012-05-03 14:27           ` Avi Kivity
2012-05-03 14:38             ` Avi Kivity
2012-05-03 13:00       ` Takuya Yoshikawa
2012-05-03 15:47         ` Peter Zijlstra
2012-05-10 22:03           ` Takuya Yoshikawa
2012-05-18  7:26             ` Ingo Molnar [this message]
2012-05-18 16:10               ` Takuya Yoshikawa
2012-05-04  2:43         ` Michael Wang

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