Re: [PATCH 2/4] swait: add the missing killable swaits

On Thu, Jun 29, 2017 at 12:40 PM, Luis R. Rodriguez [off-list ref] wrote:

On Thu, Jun 29, 2017 at 11:59:29AM -0700, Linus Torvalds wrote:

quoted

quoted

at a time... I'm probably missing your point here.

The *reason* they wake up only one seems to be that there really is
just one. It's some per-cpu idle thread for kvm, and for RCU it's the
RCU workqueue thread.

So the queue literally looks suspiciously pointless.

But I might be wrong, and there can actually be multiple entries.

Since this swake_up() --> swake_up_all() reportedly *fixed* the one wake up
issue it would seem this does queue [0].

I'm not talking about the firmware code.

That thing never had an excuse to use swait in the first place.

I'm talking about kvm and rcu, which *do* have excuses to use it, but
where I argue that swait is _still_ a questionable interface for other
reasons.

                Linus