From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id E34DC6B003D for ; Mon, 14 Dec 2009 09:33:53 -0500 (EST) Message-ID: <4B264CCA.5010609@redhat.com> Date: Mon, 14 Dec 2009 09:33:46 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 4/8] Use prepare_to_wait_exclusive() instead prepare_to_wait() References: <20091211164651.036f5340@annuminas.surriel.com> <20091214210823.BBAE.A69D9226@jp.fujitsu.com> <20091214212936.BBBA.A69D9226@jp.fujitsu.com> In-Reply-To: <20091214212936.BBBA.A69D9226@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: lwoodman@redhat.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, minchan.kim@gmail.com List-ID: On 12/14/2009 07:30 AM, KOSAKI Motohiro wrote: > if we don't use exclusive queue, wake_up() function wake _all_ waited > task. This is simply cpu wasting. > > Signed-off-by: KOSAKI Motohiro > if (zone_watermark_ok(zone, sc->order, low_wmark_pages(zone), > 0, 0)) { > - wake_up(wq); > + wake_up_all(wq); > finish_wait(wq,&wait); > sc->nr_reclaimed += sc->nr_to_reclaim; > return -ERESTARTSYS; I believe we want to wake the processes up one at a time here. If the queue of waiting processes is very large and the amount of excess free memory is fairly low, the first processes that wake up can take the amount of free memory back down below the threshold. The rest of the waiters should stay asleep when this happens. -- All rights reversed. -- 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/ . Don't email: email@kvack.org