Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 5 Feb 2001 14:10:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 5 Feb 2001 14:10:18 -0500 Received: from neon-gw.transmeta.com ([209.10.217.66]:62480 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Mon, 5 Feb 2001 14:10:03 -0500 Date: Mon, 5 Feb 2001 11:09:45 -0800 (PST) From: Linus Torvalds To: "Stephen C. Tweedie" cc: Alan Cox , Manfred Spraul , Christoph Hellwig , Steve Lord , linux-kernel@vger.kernel.org, kiobuf-io-devel@lists.sourceforge.net Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify + callback chains In-Reply-To: <20010205184911.A2116@redhat.com> Message-ID: 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 Mon, 5 Feb 2001, Stephen C. Tweedie wrote: > > Thats true for _block_ disk devices but if we want a generic kiovec then > > if I am going from video capture to network I dont need to force anything more > > than 4 byte align > > Kiobufs have never, ever required the IO to be aligned on any > particular boundary. They simply make the assumption that the > underlying buffered object can be described in terms of pages with > some arbitrary (non-aligned) start/offset. Every video framebuffer > I've ever seen satisfies that, so you can easily map an arbitrary > contiguous region of the framebuffer with a kiobuf already. Stop this idiocy, Stephen. You're _this_ close to be the first person I ever blacklist from my mailbox. Network. Packets. Fragmentation. Or just non-page-sized MTU's. It is _not_ a "series of contiguous pages". Never has been. Never will be. So stop making excuses. Also, think of protocols that may want to gather stuff from multiple places, where the boundaries have little to do with pages but are specified some other way. Imagine doing "writev()" style operations to disk, gathering stuff from multiple sources into one operation. Think of GART remappings - you can have multiple pages that show up as one "linear" chunk to the graphics device behind the AGP bridge, but that are _not_ contiguous in real memory. There just is NO excuse for the "linear series of pages" view. And if you cannot realize that, then I don't know what's wrong with you. Your arguments are obviously crap, and the stuff you seem unable to argue against (like networking) you decide to just ignore. Get your act together. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/