From: Arjan van de Ven <arjan@infradead.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
arjanvandeven@gmail.com, Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: x86: clean up smpboot.c's use of udelay+schedule
Date: Tue, 31 Jan 2012 05:32:36 -0800 [thread overview]
Message-ID: <20120131053236.3f120f11@infradead.org> (raw)
In-Reply-To: <20120131124341.GC4408@elte.hu>
On Tue, 31 Jan 2012 13:43:41 +0100
Ingo Molnar <mingo@elte.hu> wrote:
> > + usleep_range(100, 200);
>
> I'm wondering whether we could shorten this delay to say 10
> usecs and thus save 0.1 msecs (or more) from a typical SMP
> bootup?
doesn't matter really; bringing up a cpu is several orders more
expensive (> 100msec in 3.2, in 3.3 this got optimized to maybe 30 msec)
0.1 msec is the least of anyone's worries at this point ;-)
(would be nice if this was a completion, but this is rather fragile
code in general... at least not making it spin is an incremental
improvement)
next prev parent reply other threads:[~2012-01-31 13:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 4:53 x86: clean up smpboot.c's use of udelay+schedule Arjan van de Ven
2012-01-31 12:43 ` Ingo Molnar
2012-01-31 12:47 ` Peter Zijlstra
2012-01-31 12:53 ` Ingo Molnar
2012-01-31 13:01 ` Peter Zijlstra
2012-02-02 0:33 ` Paul E. McKenney
2012-02-02 8:03 ` Srivatsa S. Bhat
2012-02-02 15:23 ` Paul E. McKenney
2012-02-03 17:32 ` Paul E. McKenney
2012-01-31 13:43 ` Arjan van de Ven
2012-01-31 13:32 ` Arjan van de Ven [this message]
2012-01-31 14:30 ` Ingo Molnar
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