From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 2AF8F6B004F for ; Tue, 23 Jun 2009 13:40:41 -0400 (EDT) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id 2D93E82C52A for ; Tue, 23 Jun 2009 13:58:49 -0400 (EDT) Received: from smtp.ultrahosting.com ([74.213.175.254]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id wIxHG5tGT-aF for ; Tue, 23 Jun 2009 13:58:49 -0400 (EDT) Received: from gentwo.org (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 439BC82C4BF for ; Tue, 23 Jun 2009 13:58:48 -0400 (EDT) Date: Tue, 23 Jun 2009 13:41:41 -0400 (EDT) From: Christoph Lameter Subject: Re: Performance degradation seen after using one list for hot/cold pages. In-Reply-To: <20090623090630.f06b7b17.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20626261.51271245670323628.JavaMail.weblogic@epml20> <20090622165236.GE3981@csn.ul.ie> <20090623090630.f06b7b17.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Mel Gorman , NARAYANAN GOPALAKRISHNAN , "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "kosaki.motohiro@jp.fujitsu.com" List-ID: On Tue, 23 Jun 2009, KAMEZAWA Hiroyuki wrote: > > 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... Also no objections here. Readahead makes sense. > 1. if (likely(coild == 0)) > "likely" is necessary ? Would not think so. Code is sufficiently compact so that the processor "readahead" will have both branches in cache. > 2. Why moving pointer "list" rather than following ? > > if (cold) > list_add(&page->lru, list); > else > list_add_tail(&page->lru, list); Not sure what your point is here. Can you pickup the patch fix it up and resubmit? Mel is out for now it seems. -- 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