Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261441AbVBJTTI (ORCPT ); Thu, 10 Feb 2005 14:19:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261475AbVBJTTI (ORCPT ); Thu, 10 Feb 2005 14:19:08 -0500 Received: from e32.co.us.ibm.com ([32.97.110.130]:39837 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S261441AbVBJTQ6 (ORCPT ); Thu, 10 Feb 2005 14:16:58 -0500 Subject: Re: [RFC] Changing COW detection to be memory hotplug friendly From: Dave Hansen To: Andrea Arcangeli Cc: Hugh Dickins , IWAMOTO Toshihiro , Linux Kernel Mailing List , lhms In-Reply-To: <20050210190521.GN18573@opteron.random> References: <20050203035605.C981A7046E@sv1.valinux.co.jp> <20050210190521.GN18573@opteron.random> Content-Type: text/plain Date: Thu, 10 Feb 2005 11:16:44 -0800 Message-Id: <1108063004.29712.54.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1221 Lines: 26 On Thu, 2005-02-10 at 20:05 +0100, Andrea Arcangeli wrote: > Overall I see nothing wrong in preventing memory removal while rawio is > in flight. rawio cannot be in flight forever (ptrace and core dump as > well should complete eventually). Why can't you simply drop pages from > the freelist one by one until all of them are removed from the freelist? We actually do that, in addition to the more active methods of capturing the memory that we're about to remove. You're right, I don't really see a problem with ignoring those pages, at least in the active migration code. We would, of course, like to keep the number of things that we depend on good faith to get migrated to a minimum, but things under I/O are the least of our problems. The only thing we might want to do is put something in the rawio code to look for the PG_capture pages to ensure that it gives the migration code a shot at them every once in a while (when I/O is not in flight, obviously). -- Dave - 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/