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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org, mingo@kernel.org,
	laijs@cn.fujitsu.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
	sbw@mit.edu
Subject: Re: [PATCH RFC tip/core/rcu] Parallelize and economize NOCB kthread wakeups
Date: Wed, 2 Jul 2014 10:57:22 -0700	[thread overview]
Message-ID: <20140702175722.GX4603@linux.vnet.ibm.com> (raw)
In-Reply-To: <53B44182.4090107@redhat.com>

On Wed, Jul 02, 2014 at 01:29:38PM -0400, Rik van Riel wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> On 07/02/2014 01:26 PM, Peter Zijlstra wrote:
> > On Wed, Jul 02, 2014 at 10:08:38AM -0700, Paul E. McKenney wrote:
> >> As were others, not that long ago.  Today is the first hint that
> >> I got that you feel otherwise.  But it does look like the softirq
> >> approach to callback processing needs to stick around for awhile
> >> longer.  Nice to hear that softirq is now "sane and normal"
> >> again, I guess.  ;-)
> > 
> > Nah, softirqs are still totally annoying :-)
> > 
> > So I've lost detail again, but it seems to me that on all CPUs that
> > are actually getting ticks, waking tasks to process the RCU state
> > is entirely over doing it. Might as well keep processing their RCU
> > state from the tick as was previously done.
> 
> For CPUs that are not getting ticks (eg. because they are idle),
> is it worth waking up anything on that CPU, or would it make more
> sense to simply process their RCU callbacks on a different CPU,
> if there aren't too many pending?

Give or take the number of wakeups generated...  ;-)

							Thanx, Paul


  reply	other threads:[~2014-07-02 17:57 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-27 14:20 [PATCH RFC tip/core/rcu] Parallelize and economize NOCB kthread wakeups Paul E. McKenney
2014-06-27 15:01 ` Mathieu Desnoyers
2014-06-27 15:13   ` Mathieu Desnoyers
2014-06-27 15:21     ` Paul E. McKenney
2014-06-27 15:19   ` Paul E. McKenney
2014-07-02 12:34 ` Peter Zijlstra
2014-07-02 13:46   ` Rik van Riel
2014-07-02 16:55     ` Paul E. McKenney
2014-07-03  2:53       ` Paul E. McKenney
2014-07-02 15:39   ` Paul E. McKenney
2014-07-02 16:04     ` Peter Zijlstra
2014-07-02 17:08       ` Paul E. McKenney
2014-07-02 17:26         ` Peter Zijlstra
2014-07-02 17:29           ` Rik van Riel
2014-07-02 17:57             ` Paul E. McKenney [this message]
2014-07-03  9:49             ` Peter Zijlstra
2014-07-02 17:55           ` Paul E. McKenney
2014-07-03  9:50             ` Peter Zijlstra
2014-07-08 13:19               ` Paul E. McKenney
2014-07-03 13:12             ` Peter Zijlstra
2014-07-08 13:44               ` Paul E. McKenney
2014-07-03  3:31         ` Mike Galbraith
2014-07-03  5:21           ` Paul E. McKenney
2014-07-03  5:48             ` Mike Galbraith
2014-07-03 16:29               ` Paul E. McKenney
2014-07-04  3:23                 ` Mike Galbraith
2014-07-04  5:05                   ` Paul E. McKenney
2014-07-04  6:01                     ` Mike Galbraith
2014-07-04 21:20                       ` Paul E. McKenney
2014-07-05 13:04               ` Frederic Weisbecker

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