Re: [PATCH v4 0/3] locking/rwsem: Rwsem rearchitecture part 0

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

On Wed, Feb 13, 2019 at 05:00:14PM -0500, Waiman Long wrote:
> v4:
>  - Remove rwsem-spinlock.c and make all archs use rwsem-xadd.c.
> 
> v3:
>  - Optimize __down_read_trylock() for the uncontended case as suggested
>    by Linus.
> 
> v2:
>  - Add patch 2 to optimize __down_read_trylock() as suggested by PeterZ.
>  - Update performance test data in patch 1.
> 
> The goal of this patchset is to remove the architecture specific files
> for rwsem-xadd to make it easer to add enhancements in the later rwsem
> patches. It also removes the legacy rwsem-spinlock.c file and make all
> the architectures use one single implementation of rwsem - rwsem-xadd.c.
> 
> Waiman Long (3):
>   locking/rwsem: Remove arch specific rwsem files
>   locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all
>     archs
>   locking/rwsem: Optimize down_read_trylock()

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

with the caveat that I'm happy to exchange patch 3 back to my earlier
suggestion in case Will expesses concerns wrt the ARM64 performance of
Linus' suggestion.