From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754506AbdESNSB (ORCPT ); Fri, 19 May 2017 09:18:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35333 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751557AbdESNR5 (ORCPT ); Fri, 19 May 2017 09:17:57 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E98A65277D Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=dzickus@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com E98A65277D Date: Fri, 19 May 2017 09:17:53 -0400 From: Don Zickus To: Nicholas Piggin Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, adi-buildroot-devel@lists.sourceforge.net, linux-am33-list@redhat.com, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, uobergfe@redhat.com Subject: Re: [RFC] arch hardlockup detector interfaces improvement Message-ID: <20170519131753.sccuu7mksjertzni@redhat.com> References: <20170518155026.23799-1-npiggin@gmail.com> <20170518163028.tf2llimuo4l4l5nv@redhat.com> <20170519090731.1e49cd0d@roar.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170519090731.1e49cd0d@roar.ozlabs.ibm.com> User-Agent: NeoMutt/20170428-dirty (1.8.2) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 19 May 2017 13:17:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 19, 2017 at 09:07:31AM +1000, Nicholas Piggin wrote: > On Thu, 18 May 2017 12:30:28 -0400 > Don Zickus wrote: > > > (adding Uli) > > > > On Fri, May 19, 2017 at 01:50:26AM +1000, Nicholas Piggin wrote: > > > I'd like to make it easier for architectures that have their own NMI / > > > hard lockup detector to reuse various configuration interfaces that are > > > provided by generic detectors (cmdline, sysctl, suspend/resume calls). > > > > > > I'd also like to remove the dependency of arch hard lockup detectors > > > on the softlockup detector. The reason being these watchdogs can be > > > very small (sparc's is like a page of core code that does not use any > > > big subsystem like kthreads or timers). > > > > > > So I do this by adding a separate CONFIG_SOFTLOCKUP_DETECTOR, and > > > juggling around what goes under config options. HAVE_NMI_WATCHDOG > > > continues to be the config for arch to override the hard lockup > > > detector, which is expanded to cover a few more cases. > > > > Basically you are trying to remove the heavy HARDLOCKUP pieces to minimize > > the SOFTLOCKUP piece and use your own NMI detector, right? > > > > I am guessing you would then disable SOFTLOCKUP to remove all the kthread > > and timer stuff but continue to use the generic infrastructure to help > > manager your own NMI detector? > > Yes that's right. > > > A lot of the code is just re-organizing things and adding an explicit > > ifdef on SOFTLOCKUP, which seems fine to me. > > > > I just need to spend some time on some of your #else clauses to see what > > functionality is dropped when you use your approach. > > Okay, appreciated. I can trim down cc lists and send you my powerpc > WIP if you'd like to have a look. I am curious to know what IBM thinks there. Currently the HARDLOCKUP detector sits on top of perf. I get the impression, you are removing that dependency. Is that a permanent thing or are you thinking of switching back and forth depending on if SOFTLOCKUP is enabled or not? Cheers, Don