From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757645Ab0E1Cj7 (ORCPT ); Thu, 27 May 2010 22:39:59 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:52045 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754904Ab0E1Cj6 (ORCPT ); Thu, 27 May 2010 22:39:58 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Mel Gorman Subject: Re: [PATCH 02/10] vmscan: move priority variable into scan_control Cc: kosaki.motohiro@jp.fujitsu.com, Johannes Weiner , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Mason , Dave Chinner , Andi Kleen In-Reply-To: <20100526102330.GL29038@csn.ul.ie> References: <20100416224820.GE20640@cmpxchg.org> <20100526102330.GL29038@csn.ul.ie> Message-Id: <20100528113404.7E18.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Fri, 28 May 2010 11:39:54 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi > Sorry for the long delay on this. I got distracted by the anon_vma and > page migration stuff. Sorry for the delay too. I don't have enough development time recently ;) I had tested this patch series a while. but now they need to rebase and retest. that's sad. > On Sat, Apr 17, 2010 at 12:48:20AM +0200, Johannes Weiner wrote: > > On Thu, Apr 15, 2010 at 06:21:35PM +0100, Mel Gorman wrote: > > > From: KOSAKI Motohiro > > > > > > Now very lots function in vmscan have `priority' argument. It consume > > > stack slightly. To move it on struct scan_control reduce stack. > > > > I don't like this much because it obfuscates value communication. > > > > Functions no longer have obvious arguments and return values, as it's all > > passed hidden in that struct. > > > > Do you think it's worth it? I would much rather see that thing die than > > expand on it... > > I don't feel strongly enough to fight about it and reducing stack usage here > isn't the "fix" anyway. I'll drop this patch for now. I'm ok either. > That aside, the page reclaim algorithm maintains a lot of state and the > "priority" is part of that state. While the struct means that functions might > not have obvious arguments, passing the state around as arguments gets very > unwieldly very quickly. I don't think killing scan_control would be as > nice as you imagine although I do think it should be as small as > possible. I don't have strong opinion. I think both you and Hannes were talking correct thing. But Hannes seems to have more strong opinion. then, I'm tend to drop this one. Thanks.