From: Ingo Molnar <mingo@elte.hu>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
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 11:43:18 +0200 [thread overview]
Message-ID: <20050802094318.GC20978@elte.hu> (raw)
In-Reply-To: <42EF0E0D.8000906@yahoo.com.au>
* Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> Siddha, Suresh B 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.
> >
>
> Hmm, I would have hoped the new "all_pinned" logic should have handled
> this case properly. [...]
no, active_balance is a different case, not covered by the all_pinned
logic. This is a HT-special scenario, where busiest->nr_running == 1,
and we have to do active load-balancing. This does not go through
move_tasks() and does not set all_pinned. (If nr_running werent 1 we'd
not have to kick active load-balancing.)
Ingo
next prev parent reply other threads:[~2005-08-02 9:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-02 0:42 [Patch] don't kick ALB in the presence of pinned task Siddha, Suresh B
2005-08-02 6:09 ` Nick Piggin
2005-08-02 9:43 ` Ingo Molnar [this message]
2005-08-02 10:06 ` Nick Piggin
2005-08-02 21:12 ` Siddha, Suresh B
2005-08-02 9:27 ` Ingo Molnar
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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