linux-kernel - Re: [PATCH] lockdep: do not count lock class operations without CONFIG_DEBUG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <90b3f569-055b-dae1-b98b-6ea30823a956@yandex-team.ru>
Date:   Fri, 19 May 2017 12:28:20 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] lockdep: do not count lock class operations without
 CONFIG_DEBUG_LOCKDEP

On 19.05.2017 12:09, Peter Zijlstra wrote:
> On Fri, May 19, 2017 at 10:06:01AM +0300, Konstantin Khlebnikov wrote:
>> Currently this counter shown in /proc/lockdep if CONFIG_DEBUG_LOCKDEP=y
>> This patch disables it completely if this option is disabled.
>>
>> This counter might be useful for debugging lockdep itself, but for normal
>> debugging it seems useless. Lockstat provides more detailed statistics.
>>
>> This atomic_inc is a hot spot inside __lock_acquire() for debug kernel.
>>
>> With patch "netperf -H localhost" shows some boost: 2500 -> 2600
> 
> Nothing against these patches, but I do wonder why you're performance
> optimizing debug kernels ;-)
> 

Performance of debug features matters too
Obviously this saves time and money for massive testing