Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755216Ab0DOHS3 (ORCPT ); Thu, 15 Apr 2010 03:18:29 -0400 Received: from hera.kernel.org ([140.211.167.34]:33542 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752859Ab0DOHS1 (ORCPT ); Thu, 15 Apr 2010 03:18:27 -0400 Message-ID: <4BC6BE78.1030503@kernel.org> Date: Thu, 15 Apr 2010 16:21:28 +0900 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.1.9) Gecko/20100317 Thunderbird/3.0.4 MIME-Version: 1.0 To: Minchan Kim CC: Mel Gorman , Andrew Morton , KAMEZAWA Hiroyuki , Bob Liu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter Subject: Re: [PATCH 2/6] change alloc function in pcpu_alloc_pages References: <9918f566ab0259356cded31fd1dd80da6cae0c2b.1271171877.git.minchan.kim@gmail.com> <20100413154820.GC25756@csn.ul.ie> <4BC65237.5080408@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Thu, 15 Apr 2010 07:17:58 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1283 Lines: 32 Hello, On 04/15/2010 10:31 AM, Minchan Kim wrote: > Hi, Tejun. >> This being a pretty cold path, I don't really see much benefit in >> converting it to alloc_pages_node_exact(). It ain't gonna make any >> difference. I'd rather stay with the safer / boring one unless >> there's a pressing reason to convert. > > Actually, It's to weed out not-good API usage as well as some > performance gain. But I don't think to need it strongly. > Okay. Please keep in mind about this and correct it if you confirms > it in future. :) Hmm... if most users are converting over to alloc_pages_node_exact(), I think it would be better to convert percpu too. I thought it was a performance optimization (of rather silly kind too). So, this is to weed out -1 node id usage? Wouldn't it be better to update alloc_pages_node() such that it whines once per each caller if it's called with -1 node id and after updating most users convert the warning into WARN_ON_ONCE()? Having two variants for this seems rather extreme to me. Thanks. -- tejun -- 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/