Re: [PATCH v5 1/2] printk: Add console owner and waiter logic to load balance console writes

Steven Rostedt
2018-01-18T15:21:47Z

On Thu, 18 Jan 2018 13:01:46 +0900
Byungchul Park <byungchul.park@lge.com> wrote:

> > I disagree. It is like a spinlock. You can say a spinlock() that is
> > blocked is also waiting for an event. That event being the owner does a
> > spin_unlock().
>
> That's exactly what I was saying. Excuse me but, I don't understand
> what you want to say. Could you explain more? What do you disagree?

I guess I'm confused at what you are asking for then.

> > I find your way confusing. I'm simulating a spinlock not a wait for
> > completion. A wait for completion usually initiates something then
>
> I used the word, *event* instead of *completion*. wait_for_completion()
> and complete() are just an example of a pair of waiter and event.
> Lock and unlock can also be another example, too.
>
> Important thing is that who waits and who triggers the event. Using the
> pair, we can achieve various things, for examples:
>
> 1. Synchronization like wait_for_completion() does.
> 2. Control exclusively entering into a critical area.
> 3. Whatever.
>
> > waits for it to complete. This is trying to get into a critical area
> > but another task is currently in it. It's simulating a spinlock as far
> > as I can see.
>
> Anyway it's an example of "waiter for an event, and the event".
>
> JFYI, spinning or sleeping does not matter. Those are just methods to
> achieve a wait. I know you're not talking about this though. It's JFYI.

OK, if it is just FYI.

-- Steve