From mboxrd@z Thu Jan 1 00:00:00 1970 From: Byungchul Park Subject: Re: possible circular locking dependency detected [was: linux-next: Tree for Aug 22] Date: Wed, 30 Aug 2017 14:43:34 +0900 Message-ID: <20170830054334.GF3240@X58A-UD3R> References: <20170822183816.7925e0f8@canb.auug.org.au> <20170822104708.GA491@jagdpanzerIV.localdomain> <1503438234.2508.27.camel@wdc.com> <20170823000304.GK20323@X58A-UD3R> <20170830052037.GA432@jagdpanzerIV.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170830052037.GA432@jagdpanzerIV.localdomain> Sender: linux-block-owner@vger.kernel.org To: Sergey Senozhatsky Cc: Bart Van Assche , peterz@infradead.org, "linux-kernel@vger.kernel.org" , "linux-block@vger.kernel.org" , "martin.petersen@oracle.com" , "axboe@kernel.dk" , "linux-scsi@vger.kernel.org" , "sfr@canb.auug.org.au" , "linux-next@vger.kernel.org" , kernel-team@lge.com List-Id: linux-next.vger.kernel.org On Wed, Aug 30, 2017 at 02:20:37PM +0900, Sergey Senozhatsky wrote: > Byungchul, a quick question. Hello Sergey, > have you measured the performance impact? somehow my linux-next is Yeah, it might have performance impact inevitably. > notably slower than earlier 4.13 linux-next. (e.g. scrolling in vim > is irritatingly slow) To Ingo, I cannot decide if we have to roll back CONFIG_LOCKDEP_CROSSRELEASE dependency on CONFIG_PROVE_LOCKING in Kconfig. With them enabled, lockdep detection becomes strong but has performance impact. But, it's anyway a debug option so IMHO we don't have to take case of the performance impact. Please let me know your decision. > `time dmesg' shows some difference, but probably that's not a good > test. > > !LOCKDEP LOCKDEP LOCKDEP -CROSSRELEASE -COMPLETIONS > real 0m0.661s 0m2.290s 0m1.920s > user 0m0.010s 0m0.105s 0m0.000s > sys 0m0.636s 0m2.224s 0m1.888s > > anyone else "sees"/"can confirm" the slow down? > > > it gets back to "usual normal" when I disable CROSSRELEASE and COMPLETIONS. > > --- > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index b19c491cbc4e..cdc30ef81c5e 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1091,8 +1091,6 @@ config PROVE_LOCKING > select DEBUG_MUTEXES > select DEBUG_RT_MUTEXES if RT_MUTEXES > select DEBUG_LOCK_ALLOC > - select LOCKDEP_CROSSRELEASE > - select LOCKDEP_COMPLETIONS > select TRACE_IRQFLAGS > default n > help > > --- > > -ss