Message-Id: <200411022230.iA2MUxq18736@unix-os.sc.intel.com>
From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Andrew Theurer'" <habanero@us.ibm.com>, <kernel@kolivas.org>,
       <ricklind@us.ibm.com>, "Nick Piggin" <nickpiggin@yahoo.com.au>,
       <mingo@elte.hu>
Cc: <linux-kernel@vger.kernel.org>
Subject: RE: [RFC][PATCH] sched: aggressive idle balance
Date: Tue, 2 Nov 2004 14:34:31 -0800
Thread-Index: AcTBGQamiIpc72EvSHmRPO0laO+SkAAEL6sA
In-Reply-To: <200411021416.38119.habanero@us.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1292
Lines: 27

Andrew Theurer wrote on Tuesday, November 02, 2004 12:17 PM
>
> This patch allows more aggressive idle balances, reducing idle time in
> scenarios where should not be any, where nr_running > nr_cpus.  We have seen
> this in a couple of online transaction workloads.  Three areas are targeted:
>
> 1) In try_to_wake_up(), wake_idle() is called to move the task to a sibling if
> the task->cpu is busy and the sibling is idle.  This has been expanded to any
> idle cpu, but the closest idle cpu is picked first by starting with cpu->sd,
> then going up the domains as necessary.

It occurs to me that half of the patch only applicable to HT, like the change
in wake_idle().  And also, do you really want to put that functionality in
wake_idle()?  Seems defeating the original intention of that function, which
only tries to wake up sibling cpu as far as how I understand the code.

My setup is 4-way SMP, no HT (4-way itanium2 processor), sorry, I won't be able
to tell you how this portion of the change affect online transaction workload.

- Ken


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