From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422703AbWJXV77 (ORCPT ); Tue, 24 Oct 2006 17:59:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422705AbWJXV77 (ORCPT ); Tue, 24 Oct 2006 17:59:59 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:17613 "EHLO ogre.sisk.pl") by vger.kernel.org with ESMTP id S1422703AbWJXV76 (ORCPT ); Tue, 24 Oct 2006 17:59:58 -0400 From: "Rafael J. Wysocki" To: Pavel Machek Subject: Re: [PATCH] Use extents for recording what swap is allocated. Date: Tue, 24 Oct 2006 23:58:58 +0200 User-Agent: KMail/1.9.1 Cc: Nigel Cunningham , Andrew Morton , LKML References: <1161576857.3466.9.camel@nigel.suspend2.net> <200610242208.34426.rjw@sisk.pl> <20061024213402.GC5662@elf.ucw.cz> In-Reply-To: <20061024213402.GC5662@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200610242358.59439.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, 24 October 2006 23:34, Pavel Machek wrote: > Hi! > > > > Switch from bitmaps to using extents to record what swap is allocated; > > > they make more efficient use of memory, particularly where the allocated > > > storage is small and the swap space is large. > > > > As I said before, I like the overall idea, but I have a bunch of > > comments. > > Okay, if Rafael likes it... lets take a look. > > First... what is the _worst case_ overhead? AFAICT extents are very > good at the best case, but tend to suck for the worst case...? I think we'll usually be close to the best case, as we tend to allocate large consecutive blocks of swap space.