From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 0/5] Per superblock shrinkers V2 Date: Thu, 27 May 2010 13:32:23 -0700 Message-ID: <20100527133223.efa4740a.akpm@linux-foundation.org> References: <1274777588-21494-1-git-send-email-david@fromorbit.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, xfs@oss.sgi.com To: Dave Chinner Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:60459 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932109Ab0E0Ucm (ORCPT ); Thu, 27 May 2010 16:32:42 -0400 In-Reply-To: <1274777588-21494-1-git-send-email-david@fromorbit.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, 25 May 2010 18:53:03 +1000 Dave Chinner wrote: > This series reworks the filesystem shrinkers. We currently have a > set of issues with the current filesystem shrinkers: > > 1. There is an dependency between dentry and inode cache > shrinking that is only implicitly defined by the order of > shrinker registration. > 2. The shrinkers need to walk the superblock list and pin > the superblock to avoid unmount races with the sb going > away. > 3. The dentry cache uses per-superblock LRUs and proportions > reclaim between all the superblocks which means we are > doing breadth based reclaim. This means we touch every > superblock for every shrinker call, and may only reclaim > a single dentry at a time from a given superblock. > 4. The inode cache has a global LRU, so it has different > reclaim patterns to the dentry cache, despite the fact > that the dentry cache is generally the only thing that > pins inodes in memory. > 5. Filesystems need to register their own shrinkers for > caches and can't co-ordinate them with the dentry and > inode cache shrinkers. Nice description, but... it never actually told us what the benefit of the changes are. Presumably some undescribed workload had some undescribed user-visible problem. But what was that workload, and what was the user-visible problem, and how does the patch affect all this? Stuff like that.