From: "H. Peter Anvin" <hpa@zytor.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>,
Alok Kataria <akataria@vmware.com>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
the arch/x86 maintainers <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"alan@lxorguk.ukuu.org.uk" <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] x86: Reduce the default HZ value
Date: Thu, 07 May 2009 14:01:07 -0700 [thread overview]
Message-ID: <4A034C13.8070402@zytor.com> (raw)
In-Reply-To: <1241718302.6311.1573.camel@laptop>
Peter Zijlstra wrote:
>
> The problem with scheduling a hrtimer along with tasks is that at high
> context switch rates the timer will never fire but you do pay the
> overhead of programming the hardware each time, something that can be
> about as expensive as the whole context switch itself.
>
> Although, I guess we could amortize that by not re-programming the timer
> when the existing timer is within a reasonable period (say 1ms) of the
> requested on.
>
That seems like a reasonable optimization since we're talking about
multi-kHz context switch rates, here.
-hpa
next prev parent reply other threads:[~2009-05-07 21:07 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-04 18:44 [PATCH] x86: Reduce the default HZ value Alok Kataria
2009-05-05 21:21 ` H. Peter Anvin
2009-05-05 21:44 ` Alan Cox
2009-05-05 22:09 ` Alok Kataria
2009-05-05 22:33 ` Alan Cox
2009-05-05 23:37 ` Alok Kataria
2009-05-07 14:09 ` Christoph Lameter
2009-05-07 15:12 ` Alan Cox
2009-05-05 21:57 ` Alok Kataria
2009-05-07 14:13 ` Christoph Lameter
2009-05-07 15:14 ` Alan Cox
2009-05-07 15:20 ` Christoph Lameter
2009-05-07 15:30 ` H. Peter Anvin
2009-05-07 15:40 ` Christoph Lameter
2009-05-07 16:55 ` Jeff Garzik
2009-05-07 17:09 ` Alan Cox
2009-05-07 17:55 ` Jeff Garzik
2009-05-07 19:51 ` Alan Cox
2009-05-07 20:03 ` Jeff Garzik
2009-05-07 20:30 ` Alan Cox
2009-05-07 16:37 ` Alok Kataria
2009-05-07 17:07 ` Peter Zijlstra
2009-05-07 17:13 ` Peter Zijlstra
2009-05-07 17:18 ` Peter Zijlstra
2009-05-07 17:20 ` Christoph Lameter
2009-05-07 17:39 ` Peter Zijlstra
2009-05-07 17:40 ` Christoph Lameter
2009-05-07 17:54 ` Paul E. McKenney
2009-05-07 17:51 ` Christoph Lameter
2009-05-07 19:51 ` Paul E. McKenney
2009-05-07 17:36 ` Paul E. McKenney
2009-05-07 17:38 ` Peter Zijlstra
2009-05-07 18:01 ` Paul E. McKenney
2009-05-07 18:12 ` Christoph Lameter
2009-05-07 19:06 ` Paul E. McKenney
2009-05-07 19:53 ` Alan Cox
2009-05-07 19:56 ` Christoph Lameter
2009-05-07 20:24 ` Alan Cox
2009-05-07 20:21 ` Christoph Lameter
2009-05-08 10:32 ` Peter Zijlstra
2009-05-08 12:50 ` Paul E. McKenney
2009-05-08 14:16 ` Christoph Lameter
2009-05-08 15:06 ` Paul E. McKenney
2009-05-07 17:18 ` Christoph Lameter
2009-05-07 17:37 ` Peter Zijlstra
2009-05-07 17:34 ` Christoph Lameter
2009-05-07 17:55 ` Peter Zijlstra
2009-05-07 17:55 ` Christoph Lameter
2009-05-07 17:19 ` Christoph Lameter
2009-05-07 17:45 ` Peter Zijlstra
2009-05-07 17:50 ` Christoph Lameter
2009-05-07 19:17 ` Peter Zijlstra
2009-05-07 19:38 ` Christoph Lameter
2009-05-07 21:01 ` H. Peter Anvin [this message]
2009-05-07 16:35 ` Chris Snook
2009-05-07 16:56 ` Alok Kataria
2009-05-07 20:29 ` Chris Snook
2009-05-07 20:34 ` Alan Cox
2009-05-07 22:16 ` Ravikiran G Thirumalai
2009-05-07 22:19 ` Alok Kataria
2009-05-08 9:31 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2009-05-12 19:45 devzero
2009-05-13 23:30 ` Alok Kataria
2009-05-14 20:25 devzero
2009-05-14 20:29 ` Alan Cox
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