From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755078Ab3L1Da4 (ORCPT ); Fri, 27 Dec 2013 22:30:56 -0500 Received: from moutng.kundenserver.de ([212.227.17.8]:49933 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754957Ab3L1Day (ORCPT ); Fri, 27 Dec 2013 22:30:54 -0500 Message-ID: <1388201449.5387.70.camel@marge.simpson.net> Subject: Re: [ANNOUNCE] 3.12.6-rt9 From: Mike Galbraith To: Nicholas Mc Guire Cc: Sebastian Andrzej Siewior , linux-rt-users , LKML , Thomas Gleixner , rostedt@goodmis.org, John Kacur Date: Sat, 28 Dec 2013 04:30:49 +0100 In-Reply-To: <20131227200024.GA19505@opentech.at> References: <20131223225017.GA8623@linutronix.de> <20131227200024.GA19505@opentech.at> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Provags-ID: V02:K0:Pi7hbruh+avng5p5F9YuJ8bB7aETZqSIAN87iLaWtSG 4O9oLrlDJa0IhZxM8HhPbmUW8fk3QM0fmmPW3Pk4+CWopQHOfg ZwllzLAGh4a024hImJM3cbNDJDzLuHAv7Ptli3bgLRSSostE9D 7havboy0xg7nRltWoX/hMk4AlDtb/5aReG0C706tCaZZalUj/O m/mkGUsjVWqHq9YIZMBE3ySCZz41Sn/9W8cNTk1nhK7oei65Ki WwYng1xcCRVysT61HjOTQzlATqqhw8jpfiGdaeqzlPreGpUsXB qxiQ14xZ/knYAVSawM7f49WfBsBKKQusMMcNLVLDIi9VSteDl2 Fuwh/X0TasPOwp3pgH/Ndql7awjFTK+fZpjo2qz755Mdo/mBHc U0E7kygoAGgrw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2013-12-27 at 21:00 +0100, Nicholas Mc Guire wrote: > On Mon, 23 Dec 2013, Sebastian Andrzej Siewior wrote: > > > Dear RT folks! > > > > I'm pleased to announce the v3.12.6-rt9 patch set. > > > > Changes since v3.12.6-rt8 > > > - A patch from Thomas Gleixner not to raise the timer softirq > > unconditionally (only if a timer is pending) > > > > This one seems to deadlock early in the boot sequence on x86 > (i3/i7/Phenom-4x here and Carsten Emde also had boot failures) > > after droping this patch with: > patch -p1 -R < ../paches/timers-do-not-raise-softirq-unconditionally.patch > 3.12.6-rt9 boots up fine. cyclictest seems to be back to what it was before > (only ran for a few minutes idle and 1h with load on an i3). > > The main problem with this patch though are proceduaral isues > the commit note - which is a mail exchange - actually does not explain what > the rational for the changes is Raising the timer softirq unconditionally wakes ksoftirqd at every tick, so the only time the no_hz_full "one and only one task is runnable" tick shutdown criteria can be met is when the box has zero other runnable tasks.. i.e. when box is idle. Here, patch works fine boot wise, and no_hz_full tick shutdown works as well, but there are a couple spots where taking an interrupt is a bad idea as things sit. Watchdog barked at two such spots, and there's a "you _will_ hit this warning in -rt" spot as well. With bandaids on the sore spots, my 64 core box survives. -Mike (Less than wonderful changelogs probably comes from the fact that maintaining -rt out of tree is time consuming as all hell. Everybody gets to breaks it, a couple guys get to fix it up again and again.)