From mboxrd@z Thu Jan 1 00:00:00 1970 From: Minchan Kim Subject: Re: [PATCH 7/8] writeback: sync old inodes first in background writeback Date: Tue, 27 Jul 2010 01:30:11 +0900 Message-ID: <20100726163011.GA23467@barrios-desktop> References: <20100723094515.GD5043@localhost> <20100723105719.GE5300@csn.ul.ie> <20100725192955.40D5.A69D9226@jp.fujitsu.com> <20100725120345.GA1817@barrios-desktop> <20100726032755.GB7668@localhost> <20100726043709.GC7668@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable 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 To: Wu Fengguang Return-path: Content-Disposition: inline In-Reply-To: <20100726043709.GC7668@localhost> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Jul 26, 2010 at 12:37:09PM +0800, Wu Fengguang wrote: > On Mon, Jul 26, 2010 at 12:11:59PM +0800, Minchan Kim wrote: > > 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 a= nd willing > > >> > > to confirm the patch resolves his/her problem. I am running th= is patch on > > >> > > my desktop at the moment and it does feel a little smoother bu= t it might be > > >> > > my imagination. I had trouble with odd stalls that I never pin= ned down and > > >> > > was attributing to the machine being commonly heavily loaded b= ut 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 lump= y reclaim also > > >> > > should use PAGEOUT_IO_SYNC] > > >> > > > >> > My reviewing doesn't found any bug. however I think original thr= ead have too many guess > > >> > and we need to know reproduce way and confirm it. > > >> > > > >> > At least, we need three confirms. > > >> > =A0o original issue is still there? > > >> > =A0o 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% =3D 100M. So 32M lo= oks > > > a reasonable value. > >=20 > > 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 explana= tion. > > It might be thing _only I_ don't know. :( >=20 > It's more or less random selected. I'm also OK with 3.125%. It's an > threshold to turn on some _last resort_ mechanism, so don't need to be > optimal.. Okay. Why I had a question is that I don't want to add new magic value in= =20 VM without detailed comment.=20 While I review the source code, I always suffer form it. :( Now we have a great tool called 'git'.=20 Please write down why we select that number detaily when we add new=20 magic value. :) Thanks, Wu.=20 --=20 Kind regards, Minchan Kim -- 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