From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759841Ab3CZQgr (ORCPT ); Tue, 26 Mar 2013 12:36:47 -0400 Received: from mail-pd0-f169.google.com ([209.85.192.169]:55496 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753687Ab3CZQgp (ORCPT ); Tue, 26 Mar 2013 12:36:45 -0400 Date: Tue, 26 Mar 2013 09:36:35 -0700 From: Tejun Heo To: "J. Bruce Fields" Cc: Jeff Layton , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, skinsbursky@parallels.com, ebiederm@xmission.com, jmorris@namei.org, axboe@kernel.dk Subject: Re: [PATCHSET] idr: implement idr_alloc() and convert existing users Message-ID: <20130326163635.GC3061@htj.dyndns.org> References: <20130203170241.GA24778@fieldses.org> <20130204001557.GB24778@fieldses.org> <20130204171031.GK27963@mtj.dyndns.org> <20130204171128.GL27963@mtj.dyndns.org> <20130321140618.GD27838@fieldses.org> <20130321183513.GC20500@htj.dyndns.org> <20130326111936.550110bf@tlielax.poochiereds.net> <20130326152653.GA3061@htj.dyndns.org> <20130326163011.GC3353@fieldses.org> <20130326163351.GB3061@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130326163351.GB3061@htj.dyndns.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 26, 2013 at 09:33:51AM -0700, Tejun Heo wrote: > not be too bad. The optimal would be bitmap + hashtable, I suppose. Oops, with more restricted (or at least dynamically adjusted) ID space, that is. The problem with idr is that it can get pretty wasteful if the IDs become very scattered - the worst case being one ID per each idr_layer (the internal allocation block). That said, even cyclic allocation should yield somewhat clustered IDs, so I don't think it'd be too bad. Thanks. -- tejun