From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752702AbWLOPBY (ORCPT ); Fri, 15 Dec 2006 10:01:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752701AbWLOPBY (ORCPT ); Fri, 15 Dec 2006 10:01:24 -0500 Received: from mx1.redhat.com ([66.187.233.31]:55096 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752700AbWLOPBX (ORCPT ); Fri, 15 Dec 2006 10:01:23 -0500 Message-ID: <4582B8AF.9060707@redhat.com> Date: Fri, 15 Dec 2006 10:01:03 -0500 From: Jeff Layton User-Agent: Thunderbird 1.5.0.8 (X11/20061107) MIME-Version: 1.0 To: =?UTF-8?B?SsO2cm4gRW5nZWw=?= CC: akpm@osdl.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig Subject: Re: [PATCH 0/3] ensure unique i_ino in filesystems without permanent inode numbers (introduction) References: <457891E7.10902@redhat.com> <45829D94.1090304@redhat.com> <20061215140057.GF30508@lazybastard.org> In-Reply-To: <20061215140057.GF30508@lazybastard.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jörn Engel wrote: > On Fri, 15 December 2006 08:05:24 -0500, Jeff Layton wrote: >> Jeff Layton wrote: >>> Apologies for the long email, but I couldn't come up with a way to explain >>> this in fewer words. Many filesystems that are part of the linux kernel >>> have problems with how they have assign out i_ino values: >>> >> If there are no further comments/suggestions on this patchset, I'd like to >> ask Andrew to add it to -mm soon and target getting it rolled into 2.6.21. > > I'm still unsure whether idr has a sufficient advantage over simply > hashing the inodes. Hch has suggested that keeping the hashtable > smaller is good for performance. But idr adds new complexity, which > should be avoided on its own right. So is the performance benefit big > enough to add more complexity? Is it even measurable? > > Jörn > A very good question. Certainly, just hashing them would be a heck of a lot simpler. That was my first inclination when I looked at this, but as you said, HCH NAK'ed that idea stating that it would bloat out the hashtable. I tend to think that it's probably not that significant, but that might very much depend on workload. I'm OK with either approach, though I'd like to have some sort of buyin from Christoph on hashing the inodes before I start working on patches to do that. Christoph, care to comment? -- Jeff