From: Andrew Morton <akpm@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2
Date: Thu, 10 Oct 2013 09:43:55 -0700 [thread overview]
Message-ID: <20131010094355.6f75e5a2.akpm@linux-foundation.org> (raw)
In-Reply-To: <20131010123631.1be60315@gandalf.local.home>
On Thu, 10 Oct 2013 12:36:31 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 10 Oct 2013 09:00:44 -0700
> Andrew Morton <akpm@linux-foundation.org> wrote:
>
> > It's been ages since I looked at this stuff :( Although it isn't used
> > much, memory hotplug manages to use stop_machine() on the add/remove
> > (ie, "writer") side and nothing at all on the "reader" side. Is there
> > anything which fundamentally prevents cpu hotplug from doing the same?
>
>
> I would think that memory hotplug may require stop machine as all CPUs
> may touch that memory.
Sure.
> But we would like to remove stomp machine from
> CPU hotplug.
We do? That's news. It wasn't mentioned in the changelog and should
have been. Why?
> Why prevent all CPUs from running when we want to remove
> one?
So get_online_cpus() goes away. Nothing is more scalable than nothing!
next prev parent reply other threads:[~2013-10-10 16:43 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 10:25 [PATCH 0/6] Optimize the cpu hotplug locking -v2 Peter Zijlstra
2013-10-08 10:25 ` [PATCH 1/6] hotplug: Optimize {get,put}_online_cpus() Peter Zijlstra
2013-10-08 15:08 ` Rik van Riel
2013-10-10 5:47 ` Andrew Morton
2013-10-10 11:06 ` Oleg Nesterov
2013-10-10 14:55 ` Paul E. McKenney
2013-10-08 10:25 ` [PATCH 2/6] rcu: Create rcu_sync infrastructure Peter Zijlstra
2013-10-08 20:40 ` Jonathan Corbet
2013-10-09 19:52 ` Peter Zijlstra
2013-10-17 2:56 ` Lai Jiangshan
2013-10-17 10:36 ` Srikar Dronamraju
2013-10-08 10:25 ` [PATCH 3/6] hotplug: Optimize cpu_hotplug_{begin,done}() using rcu_sync Peter Zijlstra
2013-10-08 16:28 ` Paul E. McKenney
2013-10-08 10:25 ` [PATCH 4/6] rcusync: Introduce struct rcu_sync_ops Peter Zijlstra
2013-10-08 16:30 ` Paul E. McKenney
2013-10-17 2:07 ` Lai Jiangshan
[not found] ` <20131017154228.GL4553@linux.vnet.ibm.com>
2013-10-18 1:23 ` Lai Jiangshan
2013-10-18 12:10 ` Oleg Nesterov
2013-10-20 16:58 ` Paul E. McKenney
2013-10-08 10:25 ` [PATCH 5/6] rcusync: Add the CONFIG_PROVE_RCU checks Peter Zijlstra
2013-10-08 16:30 ` Paul E. McKenney
2013-10-08 10:25 ` [PATCH 6/6] rcusync: Introduce rcu_sync_dtor() Peter Zijlstra
2013-10-08 16:32 ` Paul E. McKenney
2013-10-08 15:27 ` [PATCH 0/6] Optimize the cpu hotplug locking -v2 Oleg Nesterov
2013-10-08 15:38 ` Peter Zijlstra
2013-10-10 5:50 ` Andrew Morton
2013-10-10 6:27 ` Ingo Molnar
2013-10-10 6:34 ` Andrew Morton
2013-10-10 7:27 ` Ingo Molnar
2013-10-10 7:33 ` Andrew Morton
2013-10-10 7:45 ` Ingo Molnar
2013-10-10 12:19 ` Peter Zijlstra
2013-10-10 14:57 ` Ingo Molnar
2013-10-10 15:21 ` Peter Zijlstra
2013-10-10 15:36 ` Oleg Nesterov
2013-10-10 16:50 ` Ingo Molnar
2013-10-10 17:13 ` Paul E. McKenney
2013-10-10 17:35 ` Ingo Molnar
2013-10-10 18:35 ` Peter Zijlstra
2013-10-10 15:26 ` Oleg Nesterov
2013-10-10 16:00 ` Andrew Morton
2013-10-10 16:36 ` Steven Rostedt
2013-10-10 16:43 ` Andrew Morton [this message]
2013-10-10 16:53 ` Peter Zijlstra
2013-10-10 17:13 ` Steven Rostedt
2013-10-10 17:48 ` Andrew Morton
2013-10-10 18:10 ` Linus Torvalds
2013-10-10 18:43 ` Steven Rostedt
2013-10-10 18:50 ` Peter Zijlstra
2013-10-10 19:15 ` Paul E. McKenney
2013-10-10 19:00 ` Linus Torvalds
2013-10-10 18:46 ` Peter Zijlstra
2013-10-10 18:34 ` Peter Zijlstra
2013-10-10 18:49 ` Linus Torvalds
2013-10-10 19:04 ` Steven Rostedt
2013-10-10 19:16 ` Linus Torvalds
2013-10-10 19:34 ` Peter Zijlstra
2013-10-10 19:34 ` Steven Rostedt
2013-10-11 6:09 ` Ingo Molnar
2013-10-11 12:38 ` Peter Zijlstra
2013-10-11 18:25 ` Oleg Nesterov
2013-10-11 20:48 ` Peter Zijlstra
2013-10-12 17:06 ` Oleg Nesterov
2013-10-14 9:05 ` Peter Zijlstra
2013-10-14 9:23 ` Paul E. McKenney
2013-10-15 1:01 ` Paul E. McKenney
2013-10-17 16:49 ` [tip:sched/core] sched: Remove get_online_cpus() usage tip-bot for Peter Zijlstra
2013-10-10 17:39 ` [PATCH 0/6] Optimize the cpu hotplug locking -v2 Oleg Nesterov
2013-10-10 16:52 ` Ingo Molnar
2013-10-10 17:44 ` Paul E. McKenney
2013-10-10 16:54 ` Oleg Nesterov
2013-10-10 19:04 ` Srivatsa S. Bhat
2013-10-10 18:52 ` Srivatsa S. Bhat
-- strict thread matches above, loose matches on Subject: below --
2013-10-11 12:14 George Spelvin
2013-10-11 12:45 ` Steven Rostedt
2013-10-11 13:51 ` George Spelvin
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