From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id 630F96B0390 for ; Tue, 28 Mar 2017 09:19:04 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id p50so56953757qtc.9 for ; Tue, 28 Mar 2017 06:19:04 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id c15si3434212qtb.14.2017.03.28.06.19.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 28 Mar 2017 06:19:03 -0700 (PDT) Date: Tue, 28 Mar 2017 15:18:54 +0200 From: Jesper Dangaard Brouer Subject: Re: Bisected softirq accounting issue in v4.11-rc1~170^2~28 Message-ID: <20170328151854.5c50dbd4@redhat.com> In-Reply-To: <20170328130602.GA4216@lerouge> References: <20170328101403.34a82fbf@redhat.com> <20170328122642.dhw2zkjbghfw4fzn@hirez.programming.kicks-ass.net> <20170328130602.GA4216@lerouge> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Frederic Weisbecker Cc: Peter Zijlstra , Wanpeng Li , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , linux-mm , Mel Gorman , Tariq Toukan , Tariq Toukan , Rik van Riel , Thomas Gleixner , Ingo Molnar , brouer@redhat.com On Tue, 28 Mar 2017 15:06:04 +0200 Frederic Weisbecker wrote: > On Tue, Mar 28, 2017 at 02:26:42PM +0200, Peter Zijlstra wrote: > > On Tue, Mar 28, 2017 at 06:34:52PM +0800, Wanpeng Li wrote: > > > > > > sched_clock_cpu(cpu) should be converted from cputime to ns. > > > > Uhm, no. sched_clock_cpu() returns u64 in ns. > > Yes, and most of the cputime_t have been converted to u64 so there > should be no such conversion issue between u64 and cputime_t anymore. > > Perhaps my commit has another side effect on softirq time accounting, > I'll see if I can reproduce. (Disclaimer without knowing anything about the scheduler code) my theory is that irqtime_account_irq() does not get invoked often enough, as in my pktgen "overload" use-case keeps softirq always running. And your change moved updating cpustat[CPUTIME_SOFTIRQ] here. Before it got updated by account_other_time() which gets invoked from irqtime_account_process_tick(). -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org