linux-kernel - Re: possible circular locking dependency detected [was: linux-next: Tree for Aug 22]

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Date:   Wed, 30 Aug 2017 15:15:11 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Byungchul Park <byungchul.park@....com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Bart Van Assche <Bart.VanAssche@....com>,
        peterz@...radead.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "sfr@...b.auug.org.au" <sfr@...b.auug.org.au>,
        "linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
        kernel-team@....com
Subject: Re: possible circular locking dependency detected [was: linux-next:
 Tree for Aug 22]

Hi,

On (08/30/17 14:43), Byungchul Park wrote:
[..]
> > 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.

well, I expected it :)

I've been running lockdep enabled kernels for years, and was OK with
the performance. but now it's just too much and I'm looking at disabling
lockdep.

a more relevant test -- compilation of a relatively small project

  LOCKDEP -CROSSRELEASE -COMPLETIONS     LOCKDEP +CROSSRELEASE +COMPLETIONS

   real    1m23.722s                      real    2m9.969s
   user    4m11.300s                      user    4m15.458s
   sys     0m49.386s                      sys     2m3.594s


you don't want to know how much time now it takes to recompile the
kernel ;)

	-ss