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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Christoph Lameter <clameter@sgi.com>,
	Petr Tesarik <ptesarik@suse.cz>, Ingo Molnar <mingo@elte.hu>,
	linux-kernel@vger.kernel.org
Subject: Re: Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable
Date: Mon, 07 Jul 2008 08:56:13 -0700	[thread overview]
Message-ID: <48723C9D.8090504@goop.org> (raw)
In-Reply-To: <200807072152.59823.nickpiggin@yahoo.com.au>

Nick Piggin wrote:
> Although, you wouldn't need to oversubscribe physical CPUs to hit
> suboptimal behaviour.
>
> Basically, I just ask for performance improvement to be measured
> with some "realistic" configuration, then it should be easier to
> justify.

Overcommitting cpus system-wide is pretty common.  A use-case is 
consolidating a pile of underused non-performance-critical servers into 
one physical machine with a lot of VMs.  It doesn't take much load to 
cause a dhcp request to the dhcp server to steal a cpu away from the 
mysql server while it holds a lock...

I'll mail out my patches so we can have a more concrete discussion shortly.

    J

  reply	other threads:[~2008-07-07 15:56 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-06 19:26 Spinlocks waiting with interrupts disabled / preempt disabled Christoph Lameter
2008-05-07  7:30 ` Ingo Molnar
2008-05-07 17:04   ` Christoph Lameter
2008-05-07 17:24     ` Christoph Lameter
2008-05-07 18:49       ` Spinlocks: Factor our GENERIC_LOCKBREAK in order to avoid spin with irqs disable Christoph Lameter
2008-05-09 10:26         ` Ingo Molnar
2008-05-09 16:28           ` Christoph Lameter
2008-06-23 17:19         ` Petr Tesarik
2008-06-23 17:54           ` Peter Zijlstra
2008-06-23 18:20           ` Christoph Lameter
2008-06-23 20:39             ` Peter Zijlstra
2008-06-23 20:45               ` Christoph Lameter
2008-06-23 20:58                 ` Peter Zijlstra
2008-06-26  2:51                   ` Jeremy Fitzhardinge
2008-06-26  6:51                     ` Peter Zijlstra
2008-06-26 15:49                       ` Jeremy Fitzhardinge
2008-06-26  9:17                     ` Petr Tesarik
2008-06-26 17:02                       ` Christoph Lameter
2008-06-26 17:48                         ` Peter Zijlstra
2008-07-07 11:50                     ` Nick Piggin
2008-07-07 11:52                       ` Nick Piggin
2008-07-07 15:56                         ` Jeremy Fitzhardinge [this message]
2008-07-08  2:08                           ` Nick Piggin
2008-07-07 15:53                       ` Jeremy Fitzhardinge
2008-07-07 19:46                     ` Rik van Riel
2008-07-07 20:14                       ` Jeremy Fitzhardinge
2008-07-08  2:07                         ` Nick Piggin
2008-07-08  5:57                           ` Jeremy Fitzhardinge
2008-07-08  8:41                             ` Nick Piggin
2008-07-08 15:58                               ` Jeremy Fitzhardinge
2008-05-09 16:35   ` Spinlocks waiting with interrupts disabled / preempt disabled Olaf Weber
2008-05-09 17:56     ` Peter Zijlstra
2008-05-09 18:00       ` Christoph Lameter
2008-05-09 18:06         ` Peter Zijlstra
2008-05-09 20:01       ` Olaf Weber

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