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SubjectRe: [PATCH 0/5] locking/lockdep: Improve lockdep performance
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On 10/02/2018 05:06 AM, Ingo Molnar wrote:
> * 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

OK, I will include the non lockdep number for comparison. However the
debug kernel has other debugging code enabled as well so the slowdown
won't be just for the enabling of lockdep.

-Longman

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