Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261568AbVDZUVJ (ORCPT ); Tue, 26 Apr 2005 16:21:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261511AbVDZUVI (ORCPT ); Tue, 26 Apr 2005 16:21:08 -0400 Received: from rrcs-24-227-247-8.sw.biz.rr.com ([24.227.247.8]:28570 "EHLO emachine.austin.ammasso.com") by vger.kernel.org with ESMTP id S261568AbVDZUTG (ORCPT ); Tue, 26 Apr 2005 16:19:06 -0400 Message-ID: <426EA220.6010007@ammasso.com> Date: Tue, 26 Apr 2005 15:18:40 -0500 From: Timur Tabi Organization: Ammasso User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041217 X-Accept-Language: en-us, en, en-gb MIME-Version: 1.0 To: Roland Dreier CC: Andrew Morton , libor@topspin.com, hch@infradead.org, linux-kernel@vger.kernel.org, openib-general@openib.org Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation References: <20050425135401.65376ce0.akpm@osdl.org> <521x8yv9vb.fsf@topspin.com> <20050425151459.1f5fb378.akpm@osdl.org> <426D6D68.6040504@ammasso.com> <20050425153256.3850ee0a.akpm@osdl.org> <52vf6atnn8.fsf@topspin.com> <20050425171145.2f0fd7f8.akpm@osdl.org> <52acnmtmh6.fsf@topspin.com> <20050425173757.1dbab90b.akpm@osdl.org> <52wtqpsgff.fsf@topspin.com> <20050426084234.A10366@topspin.com> <52mzrlsflu.fsf@topspin.com> <20050426122850.44d06fa6.akpm@osdl.org> <5264y9s3bs.fsf@topspin.com> In-Reply-To: <5264y9s3bs.fsf@topspin.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1182 Lines: 28 Roland Dreier wrote: > Yes, I agree. If an app wants to register half a page and pass the > other half to a child process, I think the only answer is "don't do > that then." How can the app know that, though? It would have to allocate I/O buffers with knowledge of page boundaries. Today, the apps just malloc() a bunch of memory and pay no attention to whether the beginning or the end of the buffer shares a page with some other, unrelated object. We may as well tell the app that it needs to page-align all I/O buffers. My point is that we can't just simply say, "Don't do that". Some entity (the kernel, libraries, whatever) should be able to tell the app that its usage of memory is going to break in some unpredictable way. -- Timur Tabi Staff Software Engineer timur.tabi@ammasso.com One thing a Southern boy will never say is, "I don't think duct tape will fix it." -- Ed Smylie, NASA engineer for Apollo 13 - 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/