From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751608AbcFFMVi (ORCPT ); Mon, 6 Jun 2016 08:21:38 -0400 Received: from vps0.lunn.ch ([178.209.37.122]:60361 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039AbcFFMVg (ORCPT ); Mon, 6 Jun 2016 08:21:36 -0400 Date: Mon, 6 Jun 2016 14:21:32 +0200 From: Andrew Lunn To: John Crispin Cc: Sean Wang , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, "David S. Miller" , Felix Fietkau Subject: Re: [PATCH 09/12] net: mediatek: increase watchdog_timeo Message-ID: <20160606122132.GM12165@lunn.ch> References: <1465108385-38286-1-git-send-email-john@phrozen.org> <1465108385-38286-10-git-send-email-john@phrozen.org> <20160605145632.GI12165@lunn.ch> <0da64a49-d100-f83d-e6d3-91b706710660@phrozen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0da64a49-d100-f83d-e6d3-91b706710660@phrozen.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Hi Andrew, > > it is waiting for the watchdog to trigger :-) TBH the 1s seems to be too > short to for the dma ring length to be flushed and i had to pick some > value and 5 is used most places. > > it really depends on the amount of packets in the queue, their length > and the mac setting. the timeout needs to be large enough that it would > not trigger incorrectly even if the mac is on 10mbit half duplex and all > frames in the queue were maximum size. So you are saying there is 5 seconds worth of traffic in the transmit ring. As a general point, not specific to this driver, is that wise? Isn't that really bad buffer bloat? I just wondered what happened to cause it to have 5 seconds worth of traffic in the transmit ring. Did downstream signal a pause? But i thought the byte queue limit was designed to prevent a big backlog in the transmit queue? At 10/Half, is it not reacting fast enough? Since it is half duplex, do you have a lot of traffic coming the other way and something is not being fair at distributing up and down traffic? I'm just wondering if by increasing the watchdog to 5 seconds, you are just hiding a problem. Andrew