Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 8 Apr 2001 19:31:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 8 Apr 2001 19:31:42 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:38051 "EHLO e31.bld.us.ibm.com") by vger.kernel.org with ESMTP id ; Sun, 8 Apr 2001 19:31:34 -0400 Importance: Normal Subject: Zero Copy IO To: linux-kernel@vger.kernel.org X-Mailer: Lotus Notes Release 5.0.3 (Intl) 21 March 2000 Message-ID: From: "Alex Q Chen" Date: Sun, 8 Apr 2001 16:31:27 -0700 X-MIMETrack: Serialize by Router on D03NM080/03/M/IBM(Release 5.0.6 |December 14, 2000) at 04/08/2001 05:31:29 PM 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 I am trying to find a way to pin down user space memory from kernel, so that these user space buffer can be used for direct IO transfer or otherwise known as "zero copying IO". Searching through the Internet and reading comments on various news groups, it would appear that most developers including Linus himself doesn't believe in the benefit of "zero copying IO". Most of the discussion however was based on network card drivers. For certain other drivers such as SCSI Tape driver, which need to handle great deal of data transfer, it would seemed still be more advantageous to enable zero copy IO than copy_from_user() and copy_to_user () all the data. Other OS such as AIX and OS2 have kernel functions that can be used to accomplish such a task. Has any ground work been done in Linux 2.4 to enable "zero copying IO"? Thanks in advance for any suggestions or comments Sincerely, Alex Chen IBM SSD Device Driver Development Office: 9000 S. Rita Rd 9032/2262 Email: aqchen@us.ibm.com Phone: (external) 520-799-5212 (Tie Line) (321)-5212 - 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/