From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752267AbdHAWYv (ORCPT ); Tue, 1 Aug 2017 18:24:51 -0400 Received: from shards.monkeyblade.net ([184.105.139.130]:39122 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752181AbdHAWYt (ORCPT ); Tue, 1 Aug 2017 18:24:49 -0400 Date: Tue, 01 Aug 2017 15:24:48 -0700 (PDT) Message-Id: <20170801.152448.1138483934474397257.davem@davemloft.net> To: grygorii.strashko@ti.com Cc: netdev@vger.kernel.org, richardcochran@gmail.com, nsekhar@ti.com, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, w-kwok2@ti.com, ivan.khoronzhuk@linaro.org, john.stultz@linaro.org, tglx@linutronix.de Subject: Re: [PATCH v4 0/4] net: ethernet: ti: cpts: fix tx timestamping timeout From: David Miller In-Reply-To: <20170728223005.21420-1-grygorii.strashko@ti.com> References: <20170728223005.21420-1-grygorii.strashko@ti.com> X-Mailer: Mew version 6.7 on Emacs 25.2 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 01 Aug 2017 15:24:49 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Grygorii Strashko Date: Fri, 28 Jul 2017 17:30:01 -0500 > With the low Ethernet connection speed cpdma notification about packet > processing can be received before CPTS TX timestamp event, which is set > when packet actually left CPSW while cpdma notification is sent when packet > pushed in CPSW fifo. As result, when connection is slow and CPU is fast > enough TX timestamping is not working properly. > Issue was discovered using timestamping tool on am57x boards with Ethernet link > speed forced to 100M and on am335x-evm with Ethernet link speed forced to 10M. > > Patch3 - This series fixes it by introducing TX SKB queue to store PTP SKBs for > which Ethernet Transmit Event hasn't been received yet and then re-check this > queue with new Ethernet Transmit Events by scheduling CPTS overflow > work more often until TX SKB queue is not empty. > > Patch 1,2 - As CPTS overflow work is time critical task it important to ensure > that its scheduling is not delayed. Unfortunately, There could be significant > delay in CPTS work schedule under high system load and on -RT which could cause > CPTS misbehavior due to internal counter overflow and there is no way to tune > CPTS overflow work execution policy and priority manually. The kthread_worker > can be used instead of workqueues, as it creates separate named kthread for > each worker and its its execution policy and priority can be configured > using chrt tool. Instead of modifying CPTS driver itself it was proposed to > it was proposed to add PTP auxiliary worker to the PHC subsystem [1], so > other drivers can benefit from this feature also. > > [1] https://www.spinics.net/lists/netdev/msg445392.html Series applied to 'net', thanks.