* Waiman Long <waiman.l...@hpe.com> wrote:
> I do have a patchset that allow us to more accurately determine the state of
> the lock owner.
>
> locking/rwsem: Add reader-owned state to the owner field
> http://www.spinics.net/lists/kernel/msg2258572.html
>
> That should eliminate the performance gap between mutex and rwsem wrt
> spinning when only writers are present. I am hoping that that patchset can
> be queued for 4.8.
Yeah, so I actually had this series merged for testing last week, but a
complication with a prereq patch made me unmerge it. But I have no fundamental
objections, at all.
I also agree with Linus's general observation that we want to make
down_write()/up_write() match mutex performance characteristics.
I think kernel developers should fundamentally be able to switch between
mutex_lock()/unlock() and down_write()/up_write() and back, without noticing
any high level behavioral changes.
Any 'reader/writer mixing' artifacts are secondary concerns and we'll sort them
out as they happen.
Thanks,
Ingo
