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 SMTP id 03C6F6B004F for ; Mon, 22 Jun 2009 20:07:56 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n5N088DW007346 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Tue, 23 Jun 2009 09:08:08 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 077E445DD7D for ; Tue, 23 Jun 2009 09:08:08 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id BD93B45DD7E for ; Tue, 23 Jun 2009 09:08:07 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id A0B901DB8040 for ; Tue, 23 Jun 2009 09:08:07 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 591C01DB8038 for ; Tue, 23 Jun 2009 09:08:04 +0900 (JST) Date: Tue, 23 Jun 2009 09:06:30 +0900 From: KAMEZAWA Hiroyuki Subject: Re: Performance degradation seen after using one list for hot/cold pages. Message-Id: <20090623090630.f06b7b17.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090622165236.GE3981@csn.ul.ie> References: <20626261.51271245670323628.JavaMail.weblogic@epml20> <20090622165236.GE3981@csn.ul.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: NARAYANAN GOPALAKRISHNAN , "linux-mm@kvack.org" , "cl@linux-foundation.org" , "akpm@linux-foundation.org" , "kosaki.motohiro@jp.fujitsu.com" List-ID: On Mon, 22 Jun 2009 17:52:36 +0100 Mel Gorman wrote: > On Mon, Jun 22, 2009 at 11:32:03AM +0000, NARAYANAN GOPALAKRISHNAN wrote: > > Hi, > > > > We are running on VFAT. > > We are using iozone performance benchmarking tool (http://www.iozone.org/src/current/iozone3_326.tar) for testing. > > > > The parameters are > > /iozone -A -s10M -e -U /tmp -f /tmp/iozone_file > > > > Our block driver requires requests to be merged to get the best performance. > > This was not happening due to non-contiguous pages in all kernels >= 2.6.25. > > > > Ok, by the looks of things, all the aio_read() requests are due to readahead > as opposed to explicit AIO requests from userspace. In this case, nothing > springs to mind that would avoid excessive requests for cold pages. > > It looks like the simpliest solution is to go with the patch I posted. > Does anyone see a better alternative that doesn't branch in rmqueue_bulk() > or add back the hot/cold PCP lists? > No objection. But 2 questions... > - list_add(&page->lru, list); > + if (likely(cold == 0)) > + list_add(&page->lru, list); > + else > + list_add_tail(&page->lru, list); > set_page_private(page, migratetype); > list = &page->lru; > } 1. if (likely(coild == 0)) "likely" is necessary ? 2. Why moving pointer "list" rather than following ? if (cold) list_add(&page->lru, list); else list_add_tail(&page->lru, list); Thanks, -Kame -- 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