Re: [PATCH 0/5] sched: Lazy preemption muck

[Sebastian Andrzej Siewior]

On 2024-10-08 21:40:05 [-0700], Ankur Arora wrote:
> > While comparing this vs what I have:
> > - need_resched()
> >   It checked both (tif_need_resched_lazy() || tif_need_resched()) while
> >   now it only looks at tif_need_resched().
> >   Also ensured that raw_irqentry_exit_cond_resched() does not trigger on
> >   lazy.
> >   I guess you can argue both ways what makes sense, just noting…
> 
> I think we want need_resched() to be only tif_need_resched(). That way
> preemption in lazy mode *only* happens at the user mode boundary.

There are places such as __clear_extent_bit() or select_collect() where
need_resched() is checked and if 0 they loop again. For these kind of
users it would probably make sense to allow them to preempt themself.
We could also add a new function which checks both and audit all users
and check what would make sense base on $criteria.

Sebastian