Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751670AbWIAPsm (ORCPT ); Fri, 1 Sep 2006 11:48:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751676AbWIAPsl (ORCPT ); Fri, 1 Sep 2006 11:48:41 -0400 Received: from hellhawk.shadowen.org ([80.68.90.175]:1028 "EHLO hellhawk.shadowen.org") by vger.kernel.org with ESMTP id S1751670AbWIAPsk (ORCPT ); Fri, 1 Sep 2006 11:48:40 -0400 Message-ID: <44F8563B.3050505@shadowen.org> Date: Fri, 01 Sep 2006 16:48:11 +0100 From: Andy Whitcroft User-Agent: Thunderbird 1.5.0.4 (X11/20060713) MIME-Version: 1.0 To: schwidefsky@de.ibm.com CC: Dave Hansen , linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, akpm@osdl.org, nickpiggin@yahoo.com.au, frankeh@watson.ibm.com, rhim@cc.gateh.edu Subject: Re: [patch 3/9] Guest page hinting: volatile page cache. References: <20060901110948.GD15684@skybase> <1157122667.28577.69.camel@localhost.localdomain> <1157124674.21733.13.camel@localhost> In-Reply-To: <1157124674.21733.13.camel@localhost> X-Enigmail-Version: 0.94.0.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 29 Martin Schwidefsky wrote: > On Fri, 2006-09-01 at 07:57 -0700, Dave Hansen wrote: >>> +#define PG_state_change 21 /* HV page state is changing. */ >>> +#define PG_discarded 22 /* HV page has been discarded. */ >> We're already desperately short on page flags on 32-bit architectures. >> It seems a wee bit silly to add two arch-generic flags for what is a >> very specialized arch-specific feature at this point. > > There are even three additional page flags if you apply the full set of > patches. > >> I know that there are 32-bit s390 kernels, but would this be a >> reasonable feature to restrict to only 64-bit kernels? That might be a >> decent compromise. > > Yes, it is definitly an option to make this a 64-bit only features. In > particular because the ESSA instruction that is used on s390 is only > available in zarch mode (=64 bit). Wow. Well there are only 7 extra bits available in 64 bit mode (the FIELDS area is larger on 64bit machines). Do we really, really need three new bits. What are they being used for here. -apw - 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/