From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Cochran Subject: Re: AF_PACKET mmap() v4... Date: Thu, 5 Nov 2015 07:53:35 +0100 Message-ID: <20151105065335.GB1824@netboy> References: <20151105.000414.1682124328670738318.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, arnd@arndb.de To: David Miller Return-path: Received: from mail-wm0-f43.google.com ([74.125.82.43]:34818 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161802AbbKEGyy (ORCPT ); Thu, 5 Nov 2015 01:54:54 -0500 Received: by wmll128 with SMTP id l128so4523462wml.0 for ; Wed, 04 Nov 2015 22:54:53 -0800 (PST) Content-Disposition: inline In-Reply-To: <20151105.000414.1682124328670738318.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Nov 05, 2015 at 12:04:14AM -0500, David Miller wrote: > So I want everyone to think about whether there are any other changes > we might want to make given that we have to make a v4 anyways. One thing I would like to see is a field for a desired transmit time. Time based scheduling is a new topic, never discussed on this list before, afaict. HW already supports this, for example, the Intel i210 card has a high priority queue where you can tell it a Tx time in terms of the PTP clock. This functionality is useful in industrial Ethernet protocols. There must be a dozen of these out there, and a new IEEE standard is in the works by Time Sensitive Networking (TSN) group. I haven't thought too much about how to implement this, but the eventual goal would be a generic time based scheduler that either uses special HW features or does best effort in SW. User space would have a socket option for desired Tx time, and this should also be available over the mmap interface. Thanks, Richard