From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933946AbdJQHMK (ORCPT ); Tue, 17 Oct 2017 03:12:10 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:51083 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933929AbdJQHMG (ORCPT ); Tue, 17 Oct 2017 03:12:06 -0400 X-Google-Smtp-Source: ABhQp+SeMBUEC/bUVCltZvT9uijS25kys3kjfVj8hHgJ4CxeE+SB8lLKQY3l6yl21mTNdV+X/AZAYQ== Date: Tue, 17 Oct 2017 09:12:02 +0200 From: Ingo Molnar To: Byungchul Park Cc: johan@kernel.org, arnd@arndb.de, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, hpa@zytor.com, tony@atomide.com, linux-tip-commits@vger.kernel.org, kernel-team@lge.com Subject: Re: [tip:locking/urgent] locking/lockdep: Disable cross-release features for now Message-ID: <20171017071202.6x22ho2o5yz74dak@gmail.com> References: <20171014072659.f2yr6mhm5ha3eou7@gmail.com> <20171016020447.GP3323@X58A-UD3R> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171016020447.GP3323@X58A-UD3R> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Byungchul Park wrote: > On Sat, Oct 14, 2017 at 04:36:51AM -0700, tip-bot for Ingo Molnar wrote: > > Commit-ID: b483cf3bc249d7af706390efa63d6671e80d1c09 > > Gitweb: https://git.kernel.org/tip/b483cf3bc249d7af706390efa63d6671e80d1c09 > > Author: Ingo Molnar > > AuthorDate: Sat, 14 Oct 2017 09:26:59 +0200 > > Committer: Ingo Molnar > > CommitDate: Sat, 14 Oct 2017 12:50:26 +0200 > > > > locking/lockdep: Disable cross-release features for now > > > > Johan Hovold reported a big lockdep slowdown on his system, caused by lockdep: > > > > > I had noticed that the BeagleBone Black boot time appeared to have > > > increased significantly with 4.14 and yesterday I finally had time to > > > investigate it. > > > > > > Boot time (from "Linux version" to login prompt) had in fact doubled > > > since 4.13 where it took 17 seconds (with my current config) compared to > > > the 35 seconds I now see with 4.14-rc4. > > > > > > I quick bisect pointed to lockdep and specifically the following commit: > > > > > > 28a903f63ec0 ("locking/lockdep: Handle non(or multi)-acquisition of a crosslock") > > > > Because the final v4.14 release is close, disable the cross-release lockdep > > features for now. > > > > Bisected-by: Johan Hovold > > Debugged-by: Johan Hovold > > Reported-by: Johan Hovold > > Cc: Arnd Bergmann > > Cc: Byungchul Park > > Cc: Linus Torvalds > > Cc: Peter Zijlstra > > Cc: Thomas Gleixner > > Cc: Tony Lindgren > > Cc: kernel-team@lge.com > > Cc: linux-arm-kernel@lists.infradead.org > > Cc: linux-mm@kvack.org > > Cc: linux-omap@vger.kernel.org > > Link: http://lkml.kernel.org/r/20171014072659.f2yr6mhm5ha3eou7@gmail.com > > Signed-off-by: Ingo Molnar > > --- > > lib/Kconfig.debug | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index 2689b7c..e270584 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -1092,8 +1092,8 @@ config PROVE_LOCKING > > select DEBUG_MUTEXES > > select DEBUG_RT_MUTEXES if RT_MUTEXES > > select DEBUG_LOCK_ALLOC > > - select LOCKDEP_CROSSRELEASE > > - select LOCKDEP_COMPLETIONS > > + select LOCKDEP_CROSSRELEASE if BROKEN > > + select LOCKDEP_COMPLETIONS if BROKEN > > I agree with disabling crossrelease as default, becasue of regression, > as I originally did. > > However, it's expected to spend more time once it's enabled. Is the > following acceptable? No, please fix performance. Thanks, Ingo