From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id E45EB6B0012 for ; Mon, 30 May 2011 19:45:59 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 2BB913EE0AE for ; Tue, 31 May 2011 08:45:56 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id F369B45DED9 for ; Tue, 31 May 2011 08:45:55 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id DC01845DED6 for ; Tue, 31 May 2011 08:45:55 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id CD34C1DB8041 for ; Tue, 31 May 2011 08:45:55 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 939AB1DB8037 for ; Tue, 31 May 2011 08:45:55 +0900 (JST) Date: Tue, 31 May 2011 08:38:59 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] mm, vmstat: Use cond_resched only when !CONFIG_PREEMPT Message-Id: <20110531083859.98e4ff43.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <1306774744.4061.5.camel@localhost.localdomain> References: <1306774744.4061.5.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Rakib Mullick Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, Christoph Lameter , Mel Gorman , KOSAKI Motohiro On Mon, 30 May 2011 22:59:04 +0600 Rakib Mullick wrote: > commit 468fd62ed9 (vmstats: add cond_resched() to refresh_cpu_vm_stats()) added cond_resched() in refresh_cpu_vm_stats. Purpose of that patch was to allow other threads to run in non-preemptive case. This patch, makes sure that cond_resched() gets called when !CONFIG_PREEMPT is set. In a preemptiable kernel we don't need to call cond_resched(). > > Signed-off-by: Rakib Mullick Hmm, what benefit do we get by adding this extra #ifdef in the code directly ? Other cond_resched() callers are not guilty in !CONFIG_PREEMPT ? Thanks, -Kame > --- > > diff --git a/mm/vmstat.c b/mm/vmstat.c > index 20c18b7..72cf857 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -461,7 +461,11 @@ void refresh_cpu_vm_stats(int cpu) > p->expire = 3; > #endif > } > + > +#ifndef CONFIG_PREEMPT > cond_resched(); > +#endif > + > #ifdef CONFIG_NUMA > /* > * Deal with draining the remote pageset of this > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org