Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756750Ab0GVTBL (ORCPT ); Thu, 22 Jul 2010 15:01:11 -0400 Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:18882 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751685Ab0GVTBG (ORCPT ); Thu, 22 Jul 2010 15:01:06 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEAIYySEx5Lc6U/2dsb2JhbACfcnLDAIU2BA Date: Fri, 23 Jul 2010 05:01:00 +1000 From: Nick Piggin To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Frank Mayhar , John Stultz Subject: VFS scalability git tree Message-ID: <20100722190100.GA22269@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2364 Lines: 53 I'm pleased to announce I have a git tree up of my vfs scalability work. git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin.git http://git.kernel.org/?p=linux/kernel/git/npiggin/linux-npiggin.git Branch vfs-scale-working The really interesting new item is the store-free path walk, (43fe2b) which I've re-introduced. It has had a complete redesign, it has much better performance and scalability in more cases, and is actually sane code now. What this does is to allow parallel name lookups to walk down common elements without any cacheline bouncing between them. It can walk across many interesting cases such as mount points, back up '..', and negative dentries of most filesystems. It does so without requiring any atomic operations or any stores at all to hared data. This also makes it very fast in serial performance (path walking is nearly twice as fast on my Opteron). In cases where it cannot continue the RCU walk (eg. dentry does not exist), then it can in most cases take a reference on the farthest element it has reached so far, and then continue on with a regular refcount-based path walk. My first attempt at this simply dropped everything and re-did the full refcount based walk. I've also been working on stress testing, bug fixing, cutting down 'XXX'es, and improving changelogs and comments. Most filesystems are untested (it's too large a job to do comprehensive stress tests on everything), but none have known issues (except nilfs2). Ext2/3, nfs, nfsd, and ram based filesystems seem to work well, ext4/btrfs/xfs/autofs4 have had light testing. I've never had filesystem corruption when testing these patches (only lockups or other bugs). But standard disclaimer: they may eat your data. Summary of a few numbers I've run. google's socket teardown workload runs 3-4x faster on my 2 socket Opteron. Single thread git diff runs 20% on same machine. 32 node Altix runs dbench on ramfs 150x faster (100MB/s up to 15GB/s). At this point, I would be very interested in reviewing, correctness testing on different configurations, and of course benchmarking. Thanks, Nick -- 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/