Re: [PATCH v2 1/2] Revert "locking/rwsem: Remove reader optimistic spinning"

[Ingo Molnar]

* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Fri, Sep 01, 2023 at 10:07:03AM +0900, Bongkyu Kim wrote:
> > This reverts commit 617f3ef95177840c77f59c2aec1029d27d5547d6.
> > 
> > In mobile environment, reader optimistic spinning is still useful
> > because there're not many readers. In my test result at android device,
> > it improves application startup time about 3.8%
> > App startup time is most important factor for android user expriences.
> > So, re-enable reader optimistic spinning by this commit. And,
> > the later patch will make it optional feature by cmdline.
> 
> I'm not seeing any mention on how this interacts with all the rwsem work
> that has been done since that commit, like the handoff rework.
> 
> Why is a straight revert a sane thing at this point?

Yeah, so this should probably be titled:

   locking/rwsem: Reintroduce reader optimistic spinning

... instead of the double-negative 'remove removal' thing that is indeed 
confusing.

Thanks,

	Ingo