From: Arjan van de Ven <arjan@infradead.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, Milton Miller <miltonm@bga.com>,
Andrew Morton <akpm@linux-foundation.org>,
arjanvandeven@gmail.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: smp: Start up non-boot CPUs asynchronously
Date: Tue, 31 Jan 2012 05:41:55 -0800 [thread overview]
Message-ID: <20120131054155.371e8307@infradead.org> (raw)
In-Reply-To: <20120131125232.GD4408@elte.hu>
On Tue, 31 Jan 2012 13:52:32 +0100
Ingo Molnar <mingo@elte.hu> wrote:
>
> The real fix would be to make the init code depend less on each
> other, i.e. have less hotplug lock dependencies. Or, if it's
> such a hot lock for a good reason, why does spinning on it slow
> down the boot process? It really shouldnt.
by inspection, anything that calls get_online_cpus()/put_online_cpus()
will block while a CPU is coming up. This is used in things like
kmem_cache_create()... which is used about everywhere.
(there's various other places... more or less it's a requirement
for using the for_each_online_cpu() api correctly)
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2012-01-31 13:40 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 4:54 smp: Start up non-boot CPUs asynchronously Arjan van de Ven
2012-01-31 12:52 ` Ingo Molnar
2012-01-31 13:41 ` Arjan van de Ven [this message]
2012-01-31 14:31 ` Ingo Molnar
2012-01-31 15:22 ` Arjan van de Ven
2012-01-31 16:12 ` Ingo Molnar
2012-01-31 16:24 ` Arjan van de Ven
2012-02-01 22:55 ` Andrew Morton
[not found] ` <CADyApD0yVOePmaLznks_h6xR_BCUjzEFUB7VtsL9vvsoHwCOVw@mail.gmail.com>
2012-02-01 23:31 ` Linus Torvalds
2012-02-14 8:17 ` Srivatsa S. Bhat
2012-02-14 8:17 ` Srivatsa S. Bhat
2012-02-14 9:48 ` Srivatsa S. Bhat
2012-02-14 9:48 ` Srivatsa S. Bhat
2012-02-14 14:31 ` Arjan van de Ven
2012-02-14 15:20 ` Peter Zijlstra
2012-02-14 15:20 ` Peter Zijlstra
2012-02-14 16:01 ` Arjan van de Ven
2012-02-14 19:57 ` Srivatsa S. Bhat
2012-02-14 19:57 ` Srivatsa S. Bhat
2012-02-14 20:00 ` Peter Zijlstra
2012-02-14 20:00 ` Peter Zijlstra
2012-02-14 21:02 ` Arjan van de Ven
2012-02-14 21:02 ` Arjan van de Ven
2012-02-14 19:32 ` Srivatsa S. Bhat
2012-02-14 19:32 ` Srivatsa S. Bhat
2012-02-14 21:28 ` Benjamin Herrenschmidt
2012-02-14 21:28 ` Benjamin Herrenschmidt
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