From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Modica Subject: Zero copy transmit Date: Tue, 29 Apr 2003 13:44:15 -0500 Sender: netdev-bounce@oss.sgi.com Message-ID: <3EAEC7FF.4040504@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: To: netdev@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Hi All, We are doing some experiementing with Altix systems (Itanium II with NUMA) and we're taking a big hit from __copy_user traffic. We would like to modify the write, writev, send and sendto interfaces such that we can avoid the __copy_user call by marking pages copy-on-write (COW) and handing them off to be transmitted. Since this requires TLB updates, we would only implement this code on platforms that defined themselves as capable of fast TLB updates. There was a lot of concern expressed on the l-k alias about COW being difficult to support becaue of the TLB update issues, but NUMA systems have to be especially quick at TLB updates, so it's something we want to take advantage of. I'm looking for comments and suggestions as to how we could do this without impacting other system types. Best Regards! Steve -- Steve Modica Manager - Networking Drivers Group "Give a man a fish, and he will eat for a day, hit him with a fish and he leaves you alone" - me