From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753212Ab0I3CID (ORCPT ); Wed, 29 Sep 2010 22:08:03 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:39033 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752401Ab0I3CIB (ORCPT ); Wed, 29 Sep 2010 22:08:01 -0400 Date: Wed, 29 Sep 2010 22:07:59 -0400 From: Christoph Hellwig To: Dave Chinner , dada1@cosmosbay.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 15/17] fs: inode per-cpu last_ino allocator Message-ID: <20100930020759.GC1535@infradead.org> References: <1285762729-17928-1-git-send-email-david@fromorbit.com> <1285762729-17928-16-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1285762729-17928-16-git-send-email-david@fromorbit.com> User-Agent: Mutt/1.5.20 (2009-08-17) 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, Sep 29, 2010 at 10:18:47PM +1000, Dave Chinner wrote: > From: Eric Dumazet > > last_ino was converted to an atomic variable to allow the inode_lock > to go away. However, contended atomics do not scale on large > machines, and new_inode() triggers excessive contention in such > situations. And the good thing is most users of new_inode couldn't care less about the fake i_ino assigned because they have a real inode number. So the first step is to move the i_ino assignment into a separate helper and only use it in those filesystems that need it. Second step is to figure out why some filesystems need iunique() and some are fine with the incrementing counter and then we should find a scalable way to generate an inode number - preferably just one and not to, but if that's not possible we need some documentation on why which one is needed.