Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265454AbTIJScC (ORCPT ); Wed, 10 Sep 2003 14:32:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265457AbTIJScB (ORCPT ); Wed, 10 Sep 2003 14:32:01 -0400 Received: from zcars04f.nortelnetworks.com ([47.129.242.57]:53644 "EHLO zcars04f.nortelnetworks.com") by vger.kernel.org with ESMTP id S265454AbTIJSb5 (ORCPT ); Wed, 10 Sep 2003 14:31:57 -0400 Message-ID: <3F5F6E12.8080802@nortelnetworks.com> Date: Wed, 10 Sep 2003 14:31:46 -0400 X-Sybari-Space: 00000000 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8) Gecko/20020204 X-Accept-Language: en-us MIME-Version: 1.0 To: Martin Konold Cc: Andrea Arcangeli , Luca Veraldi , linux-kernel@vger.kernel.org Subject: Re: Efficient IPC mechanism on Linux References: <00f201c376f8$231d5e00$beae7450@wssupremo> <200309101939.17967.martin.konold@erfrakon.de> <20030910180128.GP21086@dualathlon.random> <200309102005.36383.martin.konold@erfrakon.de> 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: 1320 Lines: 33 Martin Konold wrote: > Am Wednesday 10 September 2003 08:01 pm schrieb Andrea Arcangeli: >>with the shm/futex approch you can also have a ring buffer to handle >>parallelism better while it's at the same time zerocopy >> > > How fast will you get? I think you will get the bandwidth of a memcpy for > large chunks?! > > This is imho not really zerocopy. The data has to travel over the memory bus > involving the CPU so I would call this single copy ;-) Even with zerocopy, you have to build the message somehow. If process A builds a message and passes it to process B, then then isn't that as efficient as you can get with message passing? How does MPI do any better? However, if both processes directly map the same memory and use it directly (without "messages" as such), then I would see *that* as zerocopy. Chris -- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com - 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/