From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932458AbcIANIK (ORCPT ); Thu, 1 Sep 2016 09:08:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33270 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750825AbcIANIH (ORCPT ); Thu, 1 Sep 2016 09:08:07 -0400 Subject: Re: [PATCH] softirq: let ksoftirqd do its job To: Eric Dumazet , Jesper Dangaard Brouer References: <1472650472.14381.317.camel@edumazet-glaptop3.roam.corp.google.com> <1472650688.32433.115.camel@redhat.com> <1472652643.14381.320.camel@edumazet-glaptop3.roam.corp.google.com> <20160831164216.2901190c@redhat.com> <1472661956.14381.335.camel@edumazet-glaptop3.roam.corp.google.com> <1472665349.14381.356.camel@edumazet-glaptop3.roam.corp.google.com> <20160831214043.2f44cf08@redhat.com> <1472676150.14381.363.camel@edumazet-glaptop3.roam.corp.google.com> <20160831235116.33b1946b@redhat.com> <20160901130231.58355405@redhat.com> <20160901115356.GT10153@twins.programming.kicks-ass.net> <20160901142925.63a5031b@redhat.com> <20160901143859.730826ed@redhat.com> <1472734643.5019.9.camel@edumazet-glaptop3.roam.corp.google.com> Cc: Peter Zijlstra , David Miller , Rik van Riel , Paolo Abeni , linux-kernel , netdev , Jonathan Corbet From: Hannes Frederic Sowa Message-ID: <89b605ce-5281-ba41-2921-116bb3073098@redhat.com> Date: Thu, 1 Sep 2016 15:00:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1472734643.5019.9.camel@edumazet-glaptop3.roam.corp.google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 01 Sep 2016 13:00:13 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.09.2016 14:57, Eric Dumazet wrote: > On Thu, 2016-09-01 at 14:38 +0200, Jesper Dangaard Brouer wrote: > >> Correction, on the server-under-test, I'm actually running RHEL7.2 >> >> >>> How do I verify/check if I have enabled a cpu-cgroup? >> >> Hannes says I can look in "/proc/self/cgroup" >> >> $ cat /proc/self/cgroup >> 7:net_cls:/ >> 6:blkio:/ >> 5:devices:/ >> 4:perf_event:/ >> 3:cpu,cpuacct:/ >> 2:cpuset:/ >> 1:name=systemd:/user.slice/user-1000.slice/session-c1.scope >> >> And that "/" indicate I've not enabled cgroups, right? >> > > In my experience, I found that times displayed by top are often off for > softirq processing. > > Before applying my patch, top shows very small amount of cpu time for > udp_rcv and ksoftirqd/0 , while obviously cpu 0 is completely busy. > > Make sure to try latest Linus tree, as I did yesterday, because > apparently things are better than a few weeks back. > > BTW, even 'perf top' has sometimes problems showing me cycles spent in > softirq. I need to make sure the cpu processing NIC interrupts also > spend cycles in some user space program to get meaningful results. I think that ksoftirqd time is actually accounted to system: excerpt from irqtime_account_process_tick in kernel/sched/cputime.c if (this_cpu_ksoftirqd() == p) { /* * ksoftirqd time do not get accounted in cpu_softirq_time. * So, we have to handle it separately here. * Also, p->stime needs to be updated for ksoftirqd. */ __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ); } else if (user_tick) {