Re: [PATCH-tip v2 00/10] locking/rwsem: Rwsem rearchitecture part 1

[Davidlohr Bueso]

On Fri, 15 Feb 2019, Waiman Long wrote:

> v2:
>  - Sync up to v4 of the part 0 patch.
>  - Remove the rwsem.h->rwsem-xadd.h renaming patch & change patches
>    to modify rwsem.h instead of rwsem-xadd.h.
>  - Add a new patch to micro-optimize rwsem_try_read_lock_unqueued().
>
> This is part 1 of a 3-part (0/1/2) series to rearchitect the internal
> operation of rwsem. This depends on the v4 part 0 patches sent out
> previously
>
> https://lore.kernel.org/lkml/1550095217-12047-1-git-send-email-longman@xxxxxxxxxx
>
> This part lays the foundation for part 2 without making any functional
> changes. This part includes the following changes:
>
> 1) Move code around and micro-optimize rwsem_try_read_lock_unqueued()
>    (patches 1-4).
> 2) Enhance the DEBUG_RWSEMS_WARN_ON() macro to provide more information
>    and add additional checks (patches 5 & 6).
> 3) Make the core qspinlock_stat.h code generic (lock event counting)
>    so that it can be used by all the architectures as well as other
>    locking subsystems such as rwsem (patches 7-10). Lock event
>    counting help us visualize how frequently a code path is being
>    used as well as spotting abnormal behavior due to bugs in the code
>    without noticeably affecting kernel performance and hence behavior.
>
> Both (2) and (3) are useful debugging aids.

Yes, this will come in handy in the future. Feel free to add my:

Acked-by: Davidlohr Bueso <dbueso@xxxxxxx>

Thanks.