From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1466C7618B for ; Fri, 26 Jul 2019 15:37:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 929C7205F4 for ; Fri, 26 Jul 2019 15:37:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727719AbfGZPhH (ORCPT ); Fri, 26 Jul 2019 11:37:07 -0400 Received: from charlotte.tuxdriver.com ([70.61.120.58]:52646 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389022AbfGZPaL (ORCPT ); Fri, 26 Jul 2019 11:30:11 -0400 Received: from uucp by smtp.tuxdriver.com with local-rmail (Exim 4.63) (envelope-from ) id 1hr2Ab-0003Zd-OJ; Fri, 26 Jul 2019 11:30:09 -0400 Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by localhost.localdomain (8.15.2/8.14.6) with ESMTP id x6QFQWYh009330; Fri, 26 Jul 2019 11:26:32 -0400 Received: (from linville@localhost) by localhost.localdomain (8.15.2/8.15.2/Submit) id x6QFQWwM009329; Fri, 26 Jul 2019 11:26:32 -0400 Date: Fri, 26 Jul 2019 11:26:32 -0400 From: "John W. Linville" To: Artem Bityutskiy Cc: netdev@vger.kernel.org Subject: Re: [PATCH v2] ethtool: igb: dump RR2DCDELAY register Message-ID: <20190726152632.GB23037@tuxdriver.com> References: <20190715065228.88377-1-artem.bityutskiy@linux.intel.com> <20190715105933.40924-1-dedekind1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190715105933.40924-1-dedekind1@gmail.com> User-Agent: Mutt/1.12.0 (2019-05-25) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jul 15, 2019 at 01:59:33PM +0300, Artem Bityutskiy wrote: > From: Artem Bityutskiy > > Decode 'RR2DCDELAY' register which Linux kernel provides starting from version > 5.3. The corresponding commit in the Linux kernel is: > cd502a7f7c9c igb: add RR2DCDELAY to ethtool registers dump > > The RR2DCDELAY register is present in I210 and I211 Intel Gigabit Ethernet > chips and it stands for "Read Request To Data Completion Delay". Here is how > this register is described in the I210 datasheet: > > "This field captures the maximum PCIe split time in 16 ns units, which is the > maximum delay between the read request to the first data completion. This is > giving an estimation of the PCIe round trip time." > > In practice, this register can be used to measure the time it takes the NIC to > read data from the host memory. > > Signed-off-by: Artem Bityutskiy Queued for next release -- thanks! John -- John W. Linville Someday the world will need a hero, and you linville@tuxdriver.com might be all we have. Be ready.