Re: [PATCH] lockdep: do not count lock class operations without CONFIG_DEBUG_LOCKDEP

[Konstantin Khlebnikov]

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