From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Alok Kataria <akataria@vmware.com>,
"H. Peter Anvin" <hpa@zytor.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, 7 May 2009 12:06:32 -0700 [thread overview]
Message-ID: <20090507190632.GG6693@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.1.10.0905071404390.22107@qirst.com>
On Thu, May 07, 2009 at 02:12:15PM -0400, Christoph Lameter wrote:
> To get back to the main point: I agree with Alok that the default HZ needs
> to be as low as possible. The remaining justification is the load
> balancing and possible context switching between multiple tasks contenting
> for a processor.
>
> Is it enough if this occurs 100 times per second?
I am sorry, I got into solution mode too quickly in my earlier posts.
As long as you have enough memory for the callbacks, and as long
as you don't mind things like netfilter changes taking longer, RCU
doesn't much care what value HZ has.
> If so then we should change the default in kernel/Kconfig.hz.
But some workloads and users do care deeply about memory size and
netfilter-change speed, of course. So perhaps HPC workloads need
a different default HZ value.
Thanx, Paul
next prev parent reply other threads:[~2009-05-07 19:06 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 [this message]
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
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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