Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 4 Mar 2002 02:29:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 4 Mar 2002 02:29:30 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:27147 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Mon, 4 Mar 2002 02:29:26 -0500 Message-ID: <3C8321DE.EE6A47B0@zip.com.au> Date: Sun, 03 Mar 2002 23:27:26 -0800 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre2 i686) X-Accept-Language: en MIME-Version: 1.0 To: Jeff Garzik CC: Daniel Phillips , lkml , Steve Lord Subject: Re: [patch] delayed disk block allocation In-Reply-To: <3C7F3B4A.41DB7754@zip.com.au> <3C82E5A1.714081EA@mandrakesoft.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeff Garzik wrote: > > ... > > > > You're not even trying to apply this to swap cache right now are you? > > This is a disagreement akpm and I have, actually :) > Misunderstanding, rather. Swapfiles aren't interesting, IMO. And I agree that mkswap or swapon should just barf if the file has any holes in it. But what I refer to here is, simply, delayed allocate for swapspace. So swap_out() sticks the target page into the swapcache, marks it dirty and takes a space reservation for the page out of the swapcache's address_space. But no disk space is allocated at swap_out() time. Instead, the real disk mapping is created when the VM calls a_ops->vm_writeback() against the swapcache page's address_space. All of which rather implies a ripup-and-rewrite of half the swap code. It would certainly require a new allocator. So I just mentioned the possibility. Glad you're interested :) - - 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/