Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751281Ab0GZEMD (ORCPT ); Mon, 26 Jul 2010 00:12:03 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:57882 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750698Ab0GZEMA convert rfc822-to-8bit (ORCPT ); Mon, 26 Jul 2010 00:12:00 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=GT3HQLECfQDdqxyphHNcwPZoW90dGiopjOaLKQU1Za1ep1rS6xfihmWYIXsfTZgPXp mQTojsgNfKcH3422y+J5rgOMbo5c1FJBd7jm87bDe5NagSf1dRs4+4EIcvcsMvQXOdBr DNdoS05RSUhHo6Vead8UbbQZcabBklp8JzRhQ= MIME-Version: 1.0 In-Reply-To: <20100726032755.GB7668@localhost> References: <20100723094515.GD5043@localhost> <20100723105719.GE5300@csn.ul.ie> <20100725192955.40D5.A69D9226@jp.fujitsu.com> <20100725120345.GA1817@barrios-desktop> <20100726032755.GB7668@localhost> Date: Mon, 26 Jul 2010 13:11:59 +0900 Message-ID: Subject: Re: [PATCH 7/8] writeback: sync old inodes first in background writeback From: Minchan Kim To: Wu Fengguang Cc: KOSAKI Motohiro , Mel Gorman , Christoph Hellwig , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Johannes Weiner , KAMEZAWA Hiroyuki , Andrew Morton , Andrea Arcangeli Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3457 Lines: 86 On Mon, Jul 26, 2010 at 12:27 PM, Wu Fengguang wrote: > On Sun, Jul 25, 2010 at 08:03:45PM +0800, Minchan Kim wrote: >> On Sun, Jul 25, 2010 at 07:43:20PM +0900, KOSAKI Motohiro wrote: >> > Hi >> > >> > sorry for the delay. >> > >> > > Will you be picking it up or should I? The changelog should be more or less >> > > the same as yours and consider it >> > > >> > > Signed-off-by: Mel Gorman >> > > >> > > It'd be nice if the original tester is still knocking around and willing >> > > to confirm the patch resolves his/her problem. I am running this patch on >> > > my desktop at the moment and it does feel a little smoother but it might be >> > > my imagination. I had trouble with odd stalls that I never pinned down and >> > > was attributing to the machine being commonly heavily loaded but I haven't >> > > noticed them today. >> > > >> > > It also needs an Acked-by or Reviewed-by from Kosaki Motohiro as it alters >> > > logic he introduced in commit [78dc583: vmscan: low order lumpy reclaim also >> > > should use PAGEOUT_IO_SYNC] >> > >> > My reviewing doesn't found any bug. however I think original thread have too many guess >> > and we need to know reproduce way and confirm it. >> > >> > At least, we need three confirms. >> > ?o original issue is still there? >> > ?o DEF_PRIORITY/3 is best value? >> >> I agree. Wu, how do you determine DEF_PRIORITY/3 of LRU? >> I guess system has 512M and 22M writeback pages. >> So you may determine it for skipping max 32M writeback pages. >> Is right? > > For 512M mem, DEF_PRIORITY/3 means 32M dirty _or_ writeback pages. > Because shrink_inactive_list() first calls > shrink_page_list(PAGEOUT_IO_ASYNC) then optionally > shrink_page_list(PAGEOUT_IO_SYNC), so dirty pages will first be > converted to writeback pages and then optionally be waited on. > > The dirty/writeback pages may go up to 512M*20% = 100M. So 32M looks > a reasonable value. Why do you think it's a reasonable value? I mean why isn't it good 12.5% or 3.125%? Why do you select 6.25%? I am not against you. Just out of curiosity and requires more explanation. It might be thing _only I_ don't know. :( > >> And I have a question of your below comment. >> >> "As the default dirty throttle ratio is 20%, sync write&wait >> will hardly be triggered by pure dirty pages" >> >> I am not sure exactly what you mean but at least DEF_PRIOIRTY/3 seems to be >> related to dirty_ratio. It always can be changed by admin. >> Then do we have to determine magic value(DEF_PRIORITY/3) ?proportional to dirty_ratio? > > Yes DEF_PRIORITY/3 is already proportional to the _default_ > dirty_ratio. We could do explicit comparison with dirty_ratio > just in case dirty_ratio get changed by user. It's mainly a question > of whether deserving to add such overheads and complexity. I'd prefer > to keep the current simple form :) What I suggest is that couldn't we use recent_writeback/recent_scanned ratio? I think scan_control's new filed and counting wouldn't be a big overhead and complexity. I am not sure which ratio is best. but at least, it would make the logic scalable and sense to me. :) > > Thanks, > Fengguang > -- Kind regards, Minchan Kim -- 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/