From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o3MGUGrY214732 for ; Thu, 22 Apr 2010 11:30:16 -0500 Received: from bombadil.infradead.org (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 5D00415483C0 for ; Thu, 22 Apr 2010 09:32:17 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org [18.85.46.34]) by cuda.sgi.com with ESMTP id wGAYwTFEPM4GzWOv for ; Thu, 22 Apr 2010 09:32:17 -0700 (PDT) Date: Thu, 22 Apr 2010 12:32:11 -0400 From: Christoph Hellwig Subject: Re: [PATCH 1/2] mm: add context argument to shrinker callback Message-ID: <20100422163211.GA2478@infradead.org> References: <1271118255-21070-1-git-send-email-david@fromorbit.com> <1271118255-21070-2-git-send-email-david@fromorbit.com> <20100418001514.GA26575@infradead.org> <20100419140039.GQ5683@laptop> <20100420004149.GA14744@dastard> <20100420083840.GR5683@laptop> <20100420103216.GK15130@dastard> <20100421084004.GS5683@laptop> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20100421084004.GS5683@laptop> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Nick Piggin Cc: linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Christoph Hellwig , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton On Wed, Apr 21, 2010 at 06:40:04PM +1000, Nick Piggin wrote: > I'm saying that dynamic registration is no good, if we don't have a > way to order the shrinkers. We can happily throw in a priority field into the shrinker structure, but at this stage in the release process I'd rather have an as simple as possible fix for the regression. And just adding the context pointer which is a no-op for all existing shrinkers fits that scheme very well. If it makes you happier I can queue up a patch to add the priorities for 2.6.35. I think figuring out any meaningful priorities will be much harder than that, though. > > If a change of interface means that we end up with shorter call > > chains, less global state, more flexibilty, better batching and IO > > patterns, less duplication of code and algorithms and it doesn't > > cause any regressions, then where's the problem? > > Yep that would all be great but I don't see how the interface change > enables any of that at all. It seems to me that the advantage goes > the other way because it doesn't put as much crap into your mount > structure and you end up with an useful traversable list of mounts as > a side-effect. There really is not need for that. The Linux VFS is designed to have superblocks independent, which actually is a good thing as global state gets in the way of scalability or just clean code. Note that a mounts list would be even worse as filesystems basically are not concerned with mount points themselves. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754655Ab0DVQcS (ORCPT ); Thu, 22 Apr 2010 12:32:18 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:59043 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754180Ab0DVQcQ (ORCPT ); Thu, 22 Apr 2010 12:32:16 -0400 Date: Thu, 22 Apr 2010 12:32:11 -0400 From: Christoph Hellwig To: Nick Piggin Cc: Dave Chinner , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Christoph Hellwig , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH 1/2] mm: add context argument to shrinker callback Message-ID: <20100422163211.GA2478@infradead.org> References: <1271118255-21070-1-git-send-email-david@fromorbit.com> <1271118255-21070-2-git-send-email-david@fromorbit.com> <20100418001514.GA26575@infradead.org> <20100419140039.GQ5683@laptop> <20100420004149.GA14744@dastard> <20100420083840.GR5683@laptop> <20100420103216.GK15130@dastard> <20100421084004.GS5683@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100421084004.GS5683@laptop> User-Agent: Mutt/1.5.19 (2009-01-05) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 21, 2010 at 06:40:04PM +1000, Nick Piggin wrote: > I'm saying that dynamic registration is no good, if we don't have a > way to order the shrinkers. We can happily throw in a priority field into the shrinker structure, but at this stage in the release process I'd rather have an as simple as possible fix for the regression. And just adding the context pointer which is a no-op for all existing shrinkers fits that scheme very well. If it makes you happier I can queue up a patch to add the priorities for 2.6.35. I think figuring out any meaningful priorities will be much harder than that, though. > > If a change of interface means that we end up with shorter call > > chains, less global state, more flexibilty, better batching and IO > > patterns, less duplication of code and algorithms and it doesn't > > cause any regressions, then where's the problem? > > Yep that would all be great but I don't see how the interface change > enables any of that at all. It seems to me that the advantage goes > the other way because it doesn't put as much crap into your mount > structure and you end up with an useful traversable list of mounts as > a side-effect. There really is not need for that. The Linux VFS is designed to have superblocks independent, which actually is a good thing as global state gets in the way of scalability or just clean code. Note that a mounts list would be even worse as filesystems basically are not concerned with mount points themselves. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 1/2] mm: add context argument to shrinker callback Date: Thu, 22 Apr 2010 12:32:11 -0400 Message-ID: <20100422163211.GA2478@infradead.org> References: <1271118255-21070-1-git-send-email-david@fromorbit.com> <1271118255-21070-2-git-send-email-david@fromorbit.com> <20100418001514.GA26575@infradead.org> <20100419140039.GQ5683@laptop> <20100420004149.GA14744@dastard> <20100420083840.GR5683@laptop> <20100420103216.GK15130@dastard> <20100421084004.GS5683@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Dave Chinner , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Christoph Hellwig , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton To: Nick Piggin Return-path: Content-Disposition: inline In-Reply-To: <20100421084004.GS5683@laptop> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Apr 21, 2010 at 06:40:04PM +1000, Nick Piggin wrote: > I'm saying that dynamic registration is no good, if we don't have a > way to order the shrinkers. We can happily throw in a priority field into the shrinker structure, but at this stage in the release process I'd rather have an as simple as possible fix for the regression. And just adding the context pointer which is a no-op for all existing shrinkers fits that scheme very well. If it makes you happier I can queue up a patch to add the priorities for 2.6.35. I think figuring out any meaningful priorities will be much harder than that, though. > > If a change of interface means that we end up with shorter call > > chains, less global state, more flexibilty, better batching and IO > > patterns, less duplication of code and algorithms and it doesn't > > cause any regressions, then where's the problem? > > Yep that would all be great but I don't see how the interface change > enables any of that at all. It seems to me that the advantage goes > the other way because it doesn't put as much crap into your mount > structure and you end up with an useful traversable list of mounts as > a side-effect. There really is not need for that. The Linux VFS is designed to have superblocks independent, which actually is a good thing as global state gets in the way of scalability or just clean code. Note that a mounts list would be even worse as filesystems basically are not concerned with mount points themselves. -- 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