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From: Thomas Gleixner <tglx@linutronix.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, Jiri Bohac <jbohac@suse.cz>,
	Steven Rostedt <rostedt@goodmis.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] nohz: Prevent broadcast source from stealing full dynticks timekeeping duty
Date: Thu, 30 May 2013 15:57:17 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LFD.2.02.1305301554100.2905@ionos> (raw)
In-Reply-To: <1369845580-15273-2-git-send-email-fweisbec@gmail.com>

On Wed, 29 May 2013, Frederic Weisbecker wrote:

> The timekeeping duty is currently assigned to the CPU that
> handles the tick broadcast clock device by the time it is set in
> one shot mode.
> 
> The reason for this is not entirely clear as outlined by Jiri
> Bohac: https://patchwork.kernel.org/patch/2302951/
> 
> One could speculate though that it makes sure only one CPU
> is woken up to fixup the timekeeping max deferment. But the
> timekeeper can change anytime after the broadcast CPU becomes
> idle. So probably we can remove this as in Jiri's patch, but
> not late in the -rc's.

Looking at commit 7300711e (clockevents: broadcast fixup possible
waiters) which introduced that takeover, I really can't see a reason
why we must do that. It's safe to remove it completely even now.

Thanks,

	tglx





  reply	other threads:[~2013-05-30 13:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-29 16:39 [GIT PULL] nohz fixes Frederic Weisbecker
2013-05-29 16:39 ` [PATCH] nohz: Prevent broadcast source from stealing full dynticks timekeeping duty Frederic Weisbecker
2013-05-30 13:57   ` Thomas Gleixner [this message]
2013-05-30 14:22     ` Frederic Weisbecker
2013-05-30 14:39       ` Thomas Gleixner
2013-05-30 23:35         ` [PATCH] tick: Remove useless timekeeping duty attribution to broadcast source Frederic Weisbecker
2013-05-30 23:38 ` [GIT PULL] nohz fixes Frederic Weisbecker
2013-05-31 10:02   ` Ingo Molnar

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