From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751884AbdHCSMF (ORCPT ); Thu, 3 Aug 2017 14:12:05 -0400 Received: from vps0.lunn.ch ([178.209.37.122]:51066 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211AbdHCSMC (ORCPT ); Thu, 3 Aug 2017 14:12:02 -0400 Date: Thu, 3 Aug 2017 20:11:56 +0200 From: Andrew Lunn To: Florian Fainelli Cc: David Miller , netdev@vger.kernel.org, vivien.didelot@savoirfairelinux.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: dsa: Add support for 64-bit statistics Message-ID: <20170803181156.GJ15018@lunn.ch> References: <20170801220036.11355-1-f.fainelli@gmail.com> <20170802.164951.1316163070425929253.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 03, 2017 at 10:30:56AM -0700, Florian Fainelli wrote: > On 08/02/2017 04:49 PM, David Miller wrote: > > From: Florian Fainelli > > Date: Tue, 1 Aug 2017 15:00:36 -0700 > > > >> DSA slave network devices maintain a pair of bytes and packets counters > >> for each directions, but these are not 64-bit capable. Re-use > >> pcpu_sw_netstats which contains exactly what we need for that purpose > >> and update the code path to report 64-bit capable statistics. > >> > >> Signed-off-by: Florian Fainelli > > > > Applied, thanks. > > > > I would run ethtool -S and ifconfig under perf to see where it is > > spending so much time. > > > > This appears to be way worse than I thought, will keep digging, but for > now, I may have to send a revert. Andrew, Vivien can you see if you have > the same problems on your boards? Thanks! > > # killall iperf > # [ ID] Interval Transfer Bandwidth > [ 3] 0.0-19.1 sec 500 MBytes 220 Mbits/sec > # while true; do ethtool -S gphy; ifconfig gphy; done > ^C^C > > > [ 64.566226] INFO: rcu_sched self-detected stall on CPU > [ 64.571487] 0-...: (25999 ticks this GP) idle=006/140000000000001/0 Hi Florian I don't get anything so bad, but i think that is because of hardware restrictions. I see the ethtool; ifconfig loop goes a lot slower when there is iperf traffic, but i don't get an RCU stall. However, the board i tested on only has a 100Mbps CPU interface, and it can handle all that traffic without pushing the CPU to 100%. What is the CPU load when you run your test? Even if you are going to 100% CPU load, we still don't want RCU stalls. Andrew