Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752637Ab1FGJxo (ORCPT ); Tue, 7 Jun 2011 05:53:44 -0400 Received: from casper.infradead.org ([85.118.1.10]:49018 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752180Ab1FGJxn convert rfc822-to-8bit (ORCPT ); Tue, 7 Jun 2011 05:53:43 -0400 Subject: Re: [PATCH] sched: remove redundant check in select_task_rq_fair From: Peter Zijlstra To: "Nikunj A. Dadhania" Cc: mingo@elte.hu, linux-kernel@vger.kernel.org In-Reply-To: <20110607094821.29969.50197.stgit@IBM-009124035060.in.ibm.com> References: <20110607094821.29969.50197.stgit@IBM-009124035060.in.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 07 Jun 2011 11:53:34 +0200 Message-ID: <1307440414.2322.236.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1084 Lines: 31 On Tue, 2011-06-07 at 15:18 +0530, Nikunj A. Dadhania wrote: > When balancing for wakeup affinity, a redundant check can removed. Yes, tempting, but no, now you've got an extra call to wake_affine(), which is more expensive. > Signed-off-by: Nikunj A. Dadhania > --- > kernel/sched_fair.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c > index 433491c..b9e5701 100644 > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1753,7 +1753,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) > } > > if (affine_sd) { > - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync)) > + if (wake_affine(affine_sd, p, sync)) > prev_cpu = cpu; > > new_cpu = select_idle_sibling(p, prev_cpu); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/