From: Ingo Molnar <mingo@elte.hu>
To: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: nickpiggin@yahoo.com.au, akpm@osdl.org,
linux-kernel@vger.kernel.org, steiner@sgi.com
Subject: Re: [Patch] don't kick ALB in the presence of pinned task
Date: Tue, 2 Aug 2005 11:27:17 +0200 [thread overview]
Message-ID: <20050802092717.GB20978@elte.hu> (raw)
In-Reply-To: <20050801174221.B11610@unix-os.sc.intel.com>
* Siddha, Suresh B <suresh.b.siddha@intel.com> wrote:
> Jack Steiner brought this issue at my OLS talk.
>
> Take a scenario where two tasks are pinned to two HT threads in a physical
> package. Idle packages in the system will keep kicking migration_thread
> on the busy package with out any success.
>
> We will run into similar scenarios in the presence of CMP/NUMA.
>
> Patch appended.
>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
nice catch!
fine for -mm, but i dont think we need this fix in 2.6.13, as the effect
of the bug is an extra context-switch per 'CPU goes idle' event, in this
very specific (and arguably broken) task binding scenario. In a
worst-case scenario a CPU going idle can 'spam' that other CPU with
migration requests, but it still seems like a pretty artificial workload
scenario where the system has significant idle time left. I have tested
your fix on a HT box and it solves the problem.
Acked-by: Ingo Molnar <mingo@elte.hu>
Ingo
next prev parent reply other threads:[~2005-08-02 9:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-02 0:42 Siddha, Suresh B
2005-08-02 6:09 ` Nick Piggin
2005-08-02 9:43 ` Ingo Molnar
2005-08-02 10:06 ` Nick Piggin
2005-08-02 21:12 ` Siddha, Suresh B
2005-08-02 9:27 ` Ingo Molnar [this message]
2005-08-09 23:08 ` allow the load to grow upto its cpu_power (was Re: [Patch] don't kick ALB in the presence of pinned task) Siddha, Suresh B
2005-08-10 0:27 ` Nick Piggin
2005-08-10 2:03 ` Siddha, Suresh B
2005-08-11 3:09 ` Nick Piggin
2005-08-11 18:14 ` Siddha, Suresh B
2005-08-11 23:49 ` Nick Piggin
2005-08-12 0:39 ` Siddha, Suresh B
2005-08-12 1:24 ` Nick Piggin
2005-08-12 1:44 ` Siddha, Suresh B
2005-08-10 7:16 ` Ingo Molnar
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