Re: [PATCH v4 0/8] Remove dependency on congestion_wait in mm/

[Mel Gorman]

On Fri, Oct 22, 2021 at 10:26:30PM +1100, NeilBrown wrote:
> On Fri, 22 Oct 2021, Mel Gorman wrote:
> > On Fri, Oct 22, 2021 at 12:15:10PM +1100, NeilBrown wrote:
> > 
> > > In general, I still don't like the use of wake_up_all(), though it won't
> > > cause incorrect behaviour.
> > > 
> > 
> > Removing wake_up_all would be tricky.
> 
> I think there is a misunderstanding.  Removing wake_up_all() is as
> simple as
>    s/wake_up_all/wake_up/
> 
> If you used prepare_to_wait_exclusive(), then wake_up() would only wake
> one waiter, while wake_up_all() would wake all of them.
> As you use prepare_to_wait(), wake_up() will wake all waiters - as will
> wake_up_all(). 
> 

Ok, yes, there was a misunderstanding. I thought you were suggesting a
move to exclusive wakeups. I felt that the wake_up_all was explicit in
terms of intent and that I really meant for all tasks to wake instead of
one at a time.

-- 
Mel Gorman
SUSE Labs