Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932770AbcCHJvL (ORCPT ); Tue, 8 Mar 2016 04:51:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42318 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932084AbcCHJvH (ORCPT ); Tue, 8 Mar 2016 04:51:07 -0500 Date: Tue, 8 Mar 2016 10:50:56 +0100 From: Jesper Dangaard Brouer To: Willem de Bruijn Cc: "netdev@vger.kernel.org" , Tom Herbert , "linux-kernel@vger.kernel.org" , erdnetdev@gmail.com Subject: Re: Tool for sampling /proc/net/softnet_stat statistics Message-ID: <20160308105056.5bb35bff@redhat.com> In-Reply-To: References: <20160307163607.1da5f17e@redhat.com> Organization: Red Hat Inc. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2344 Lines: 56 On Mon, 7 Mar 2016 12:54:13 -0500 Willem de Bruijn wrote: > On Mon, Mar 7, 2016 at 10:36 AM, Jesper Dangaard Brouer > wrote: > > Hi Google, > > > > While playing with RPS, I needed to read stats from > > /proc/net/softnet_stat and the tools I could find [1] and [2] was not > > very good. > > > > I lack of better, I coded up my own tool softnet_stat.pl here: > > https://github.com/netoptimizer/network-testing/blob/master/bin/softnet_stat.pl > > > > The output format/columns in /proc/net/softnet_stat is undocumented, > > plus values are printed in hex. E.g. to decode the columns you need to > > read kernel function kernel softnet_seq_show() in > > kernel/net/core/net-procfs.c. > > > > To make things easier I wrote this small perl script for get > > so human readable statistics from /proc/net/softnet_stat. > > Very nice. Thanks for sharing, Jesper. I maintained something similar, > but never got around to clean up and upstream it. Will start using > yours, instead. > > A few points, from using my earlier tool: > > A minimum cut-off value is helpful, especially on beefy servers, to > suppress the many 0 rows. Preferably configurable, to also be able to > suppress low-rate background traffic when analyzing a few large > streams. My default was 500. > > The number of columns has grown with kernel versions. The latest > column is flow_limit, added in 3.11 at99bbc7074190. It is helpful for > the script to be robust against both older and future kernels. On > which note, to be able to support these kinds of tools, any new > columns to such procfs files should be appended, not inserted as for > instance in https://patchwork.ozlabs.org/patch/574171/ > > Time squeeze is an exception, in that it is number of squeeze events > per second, not number of packets squeezed. This is often > misunderstood if not explained clearly. Thanks a lot for your feedback. I don't have time to address it right away, so I've instead added a section with future development todo's. So, I don't forget this valuable feedback :-) https://github.com/netoptimizer/network-testing/commit/c464676e456aab -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer