From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261777AbVEEB1l (ORCPT ); Wed, 4 May 2005 21:27:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261782AbVEEB1l (ORCPT ); Wed, 4 May 2005 21:27:41 -0400 Received: from mx1.redhat.com ([66.187.233.31]:58561 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S261777AbVEEB1j (ORCPT ); Wed, 4 May 2005 21:27:39 -0400 Date: Wed, 4 May 2005 21:27:21 -0400 (EDT) From: Rik van Riel X-X-Sender: riel@chimarrao.boston.redhat.com To: William Jordan cc: Andy Isaacson , Caitlin Bestler , Andrew Morton , linux-kernel@vger.kernel.org, openib-general@openib.org, hch@infradead.org, Timur Tabi Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation In-Reply-To: <78d18e2050504112240e43a08@mail.gmail.com> Message-ID: References: <469958e00504291731eb8287c@mail.gmail.com> <20050503184325.GA19351@hexapodia.org> <78d18e2050504112240e43a08@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 4 May 2005, William Jordan wrote: > On 5/3/05, Andy Isaacson wrote: > > Rather than replacing the fully-registered pages with pages of zeros, > > you could simply unmap them. > > I don't like this option. It is nearly free to map all of the pages to > the zero-page. You never have to allocate a page if the user never > writes to it. Unmapping should work fine, as long as the VMA flags are set appropriately. The page fault handler can take care of the rest... -- "Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." - Brian W. Kernighan