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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: vatsa@linux.vnet.ibm.com
Cc: Mike Galbraith <efault@gmx.de>,
	"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	Dhaval Giani <dhaval@linux.vnet.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
	Aneesh Kumar KV <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: volanoMark regression with kernel 2.6.26-rc1
Date: Thu, 15 May 2008 10:41:38 +0200	[thread overview]
Message-ID: <1210840898.21616.27.camel@twins> (raw)
In-Reply-To: <20080515082033.GA14823@linux.vnet.ibm.com>

On Thu, 2008-05-15 at 13:50 +0530, Srivatsa Vaddagiri wrote:
> On Wed, May 14, 2008 at 05:12:47PM +0200, Peter Zijlstra wrote:
> > A few other things I found that make a significant difference:
> 
> One more observation: access to aggregate()->rq_weight etc arent
> correctly synchronized i.e while a cpu is doing a aggregate_walk_tree()
> in a domain, and thus possibly modifying rq_weight, load etc, other cpus could 
> be concurrently accessing the same data. As a result, its possible to
> see inconsistent rq_weight, load, task_weight combination?

Yes - and that should not be too big an issue as long as we can deal
with it.

Any number we'll put to it will be based on a snapshot of the state so
we're wrong no matter what we do. The trick is trying to keep sane.

My current stack on top of sched-devel:

http://programming.kicks-ass.net/kernel-patches/sched-smp-group-fixes/

I've found that:
http://programming.kicks-ass.net/kernel-patches/sched-smp-group-fixes/sched-agg-update-move_tasks.patch

was sufficient to deal with all the anomalities I've found so far.


  reply	other threads:[~2008-05-15  8:41 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-06  2:06 volanoMark regression with kernel 2.6.26-rc1 Zhang, Yanmin
2008-05-06  5:41 ` Zhang, Yanmin
2008-05-06 11:52 ` Dhaval Giani
2008-05-07 17:33   ` Dhaval Giani
2008-05-08  5:18     ` Zhang, Yanmin
2008-05-08  5:32       ` Dhaval Giani
2008-05-08  5:40       ` Dhaval Giani
2008-05-08  5:53         ` Zhang, Yanmin
2008-05-08  6:04           ` Dhaval Giani
2008-05-08  6:11           ` Srivatsa Vaddagiri
2008-05-09 15:52             ` Srivatsa Vaddagiri
2008-05-09 15:54               ` Srivatsa Vaddagiri
2008-05-12  1:39               ` Zhang, Yanmin
2008-05-12  2:04                 ` Dhaval Giani
2008-05-12  2:37                 ` Srivatsa Vaddagiri
2008-05-12  3:33                   ` Zhang, Yanmin
2008-05-12  4:52                     ` Srivatsa Vaddagiri
2008-05-12  5:02                       ` Zhang, Yanmin
2008-05-12  5:43                         ` Zhang, Yanmin
2008-05-12  9:04                         ` Mike Galbraith
2008-05-12  9:20                           ` Peter Zijlstra
2008-05-14  9:22                             ` Zhang, Yanmin
2008-05-14 13:44                             ` Srivatsa Vaddagiri
2008-05-14 14:50                               ` Mike Galbraith
2008-05-14 15:12                               ` Peter Zijlstra
2008-05-15  8:20                                 ` Srivatsa Vaddagiri
2008-05-15  8:41                                   ` Peter Zijlstra [this message]
2008-05-15 17:10                                     ` Srivatsa Vaddagiri
2008-05-07  7:04 ` Andrew Morton
2008-05-07  9:17 ` Ingo Molnar
2008-05-07  9:33   ` Zhang, Yanmin
2008-05-07 17:34   ` Peter Zijlstra
2008-05-07 18:58     ` Peter Zijlstra
2008-05-08  6:07       ` Zhang, Yanmin
2008-05-08  5:20     ` Zhang, Yanmin
2008-05-08  5:34       ` Dhaval Giani
2008-05-08  6:43       ` Peter Zijlstra
2008-05-07 17:42 ` Dhaval Giani
2008-05-08  5:21   ` Zhang, Yanmin
2008-05-08  5:39     ` Dhaval Giani
2008-05-08  6:03       ` Zhang, Yanmin

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