Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262596AbVDGXhZ (ORCPT ); Thu, 7 Apr 2005 19:37:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262580AbVDGXhZ (ORCPT ); Thu, 7 Apr 2005 19:37:25 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:29606 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id S262596AbVDGXhK (ORCPT ); Thu, 7 Apr 2005 19:37:10 -0400 Subject: Re: ext3 allocate-with-reservation latencies From: Mingming Cao Reply-To: cmm@us.ibm.com To: "Stephen C. Tweedie" Cc: Ingo Molnar , Lee Revell , linux-kernel , Andrew Morton In-Reply-To: <1112879303.2859.78.camel@sisko.sctweedie.blueyonder.co.uk> References: <1112673094.14322.10.camel@mindpipe> <20050405041359.GA17265@elte.hu> <1112765751.3874.14.camel@localhost.localdomain> <20050407081434.GA28008@elte.hu> <1112879303.2859.78.camel@sisko.sctweedie.blueyonder.co.uk> Content-Type: text/plain Organization: IBM LTC Date: Thu, 07 Apr 2005 16:37:02 -0700 Message-Id: <1112917023.3787.75.camel@dyn318043bld.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-3) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1172 Lines: 28 On Thu, 2005-04-07 at 14:08 +0100, Stephen C. Tweedie wrote: > Hi, > > On Thu, 2005-04-07 at 09:14, Ingo Molnar wrote: > > > doesnt the first option also allow searches to be in parallel? > > In terms of CPU usage, yes. But either we use large windows, in which > case we *can't* search remotely near areas of the disk in parallel; or > we use small windows, in which case failure to find a free bit becomes > disproportionately expensive (we have to do an rbtree link and unlink > for each window we search.) Actually, we do not have to do an rbtree link and unlink for every window we search. If the reserved window(old) has no free bit and the new reservable window's is right after the old one, no need to unlink the old window from the rbtree and then link the new window, just update the start and end of the old one. That's in the current designed already, to reduce the cost of rbtree link and unlink. Mingming - 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/