Re: [PATCH 0/5] locking/lockdep: Improve lockdep performance

[Ingo Molnar <mingo@kernel.org>]

* Waiman Long <longman@redhat.com> wrote:

> Enabling CONFIG_LOCKDEP and other related debug options will greatly
> reduce system performance. This patchset aims to reduce the performance
> slowdown caused by the lockdep code.
> 
> Patch 1 just removes an inline function that wasn't used.
> 
> Patches 2 and 3 are minor twists to optimize the code.
> 
> Patch 4 makes class->ops a per-cpu counter.
> 
> Patch 5 moves the lock_release() call outside of a lock critical section.
> 
> Parallel kernel compilation tests (make -j <#cpu>) were performed on
> 2 different systems:
> 
>  1) an 1-socket 22-core 44-thread Skylake system
>  2) a 4-socket 72-core 144-thread Broadwell system
> 
> The build times with pre-patch and post-patch debug kernels were:
> 
>    System      Pre-patch     Post-patch    %Change
>    ------      ---------     ----------    -------
>   1-socket      8m53.9s        8m41.2s      -2.4%
>   4-socket      7m27.0s        5m31.0s      -26%
> 
> I think it is the last 2 patches that yield most of the performance
> improvement.

Impressive speedup!

Mind including the non-lockdep numbers as well, for reference?

Thanks,

	Ingo