From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B355FCA9EAF for ; Mon, 21 Oct 2019 14:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 858562084C for ; Mon, 21 Oct 2019 14:09:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="zgDfAzKx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729291AbfJUOJe (ORCPT ); Mon, 21 Oct 2019 10:09:34 -0400 Received: from merlin.infradead.org ([205.233.59.134]:56670 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727344AbfJUOJd (ORCPT ); Mon, 21 Oct 2019 10:09:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=eGE87WasWvAZRrliofAskcX6jOVuVTgdyEc8K2kaY9E=; b=zgDfAzKxJll3WnPmislBw4XlD jvA92XRULfcDJU2Wc2VcX2mmnQYAkO29N/ZaXZULMlwY/T+zsSojytnCQhOYhd/JUIi0P6luvqP8X sPTPlKdQSe+F11Qap2TMrxmIezEHa+gpuhUtHETlK2UZmP6HEL6rIUM3TPIw4ZJV2pujfhc9G/Pdm HBzx4aEKxynzo+mQnu/1VnGaHWsBlMIvI3OowVJ5wGe4OTlTswauQfzqgXyGx6bF3NYlkLV8YpDHH x1AoNa+S00Hx1OumvMrqYyACCW5SmWznuXU5zIOz4+yKfz5xcuyYIwJZ3IXEKVA1bpgobJ55SBHfM Uz612X0Bg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iMYND-0005k7-JC; Mon, 21 Oct 2019 14:09:28 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id F1D1D301124; Mon, 21 Oct 2019 16:08:28 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 15C52238D26BD; Mon, 21 Oct 2019 16:09:26 +0200 (CEST) Date: Mon, 21 Oct 2019 16:09:26 +0200 From: Peter Zijlstra To: Petr Mladek Cc: Thomas Gleixner , Ingo Molnar , Laurence Oberman , Vincent Whitchurch , Michal Hocko , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] watchdog/softlockup: Report the same softlockup regularly Message-ID: <20191021140926.GH1817@hirez.programming.kicks-ass.net> References: <20190819104732.20966-1-pmladek@suse.com> <20190819104732.20966-3-pmladek@suse.com> <20191021124339.GE1817@hirez.programming.kicks-ass.net> <20191021134038.fz2cdpxrd3p3yhb7@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191021134038.fz2cdpxrd3p3yhb7@pathway.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 21, 2019 at 03:40:38PM +0200, Petr Mladek wrote: > On Mon 2019-10-21 14:43:39, Peter Zijlstra wrote: > > On Mon, Aug 19, 2019 at 12:47:31PM +0200, Petr Mladek wrote: > > > Softlockup report means that there is no progress on the given CPU. It > > > might be a "short" affair where the system gets recovered. But often > > > the system stops being responsive and need to get rebooted. > > > > > > The softlockup might be root of the problems or just a symptom. It might > > > be a deadlock, livelock, or often repeated state. > > > > > > Regular reports help to distinguish different situations. Fortunately, > > > the watchdog is finally able to show correct information how long > > > softlockup_fn() was not scheduled. > > > > > > Report before this patch: > > > > > > [ 320.248948] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4916] > > > > > > And after this patch: > > > > > > [ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943] > > > [ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943] > > > [ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943] > > > [ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943] > > > > > > Note that the horrible code never really worked before the accounting > > > was fixed. The last working timestamp was regularly lost by the many > > > touch*watchdog() calls. > > > > So what's the point of patch 1? Just confusing people? > > I was not sure what was the expected behavior. The code actually > looked like only the first report was wanted. But it probably never > worked that way. Not that I can remember at least :-) I normally don't bother with the actual time, and if I do then I look at the printk timestamps to figure out how long thing've been stuck. But this is indeed nicer.. > Should I squash the two patches and send it again, please? Probably makes sense to squash it. That also avoids having to ever expose that ugleh :-)