[PATCH] ARM: formalize an IPI for CPU wake-ups

[Russell King - ARM Linux]

On Mon, Jun 11, 2012 at 03:11:05PM -0400, Nicolas Pitre wrote:
> On Mon, 11 Jun 2012, Russell King - ARM Linux wrote:
> 
> > On Mon, Jun 11, 2012 at 02:40:24PM -0400, Nicolas Pitre wrote:
> > > On Mon, 11 Jun 2012, Russell King - ARM Linux wrote:
> > > 
> > > > On Mon, Jun 11, 2012 at 01:18:28PM -0400, Nicolas Pitre wrote:
> > > > > And that message certainly has to go as it may be triggered multiple 
> > > > > times per second in some use cases here.
> > > > 
> > > > That, I interpret, as an attempt to use CPU hotplugging for power
> > > > saving.
> > > > 
> > > > No.  Do not do that.  Under any circumstances.  Not only is the CPU
> > > > hotplugging code racy in places, it also totally destroys the ability
> > > > to have threads bound to CPUs, or even interrupts to CPUs.
> > > 
> > > [ more comments ommitted ]
> > > 
> > > Russell, let me suggest you take the time to read this:
> > > 
> > > 	http://lwn.net/Articles/481055/
> > > 
> > > then let's restart this conversation if you please.
> > 
> > Same comments apply for exactly the reasons I stated.
> 
> No they don't.  They can't. The generic kernel code doesn't know what is 
> happening behind the scene and may not even care if at the low level a 
> complete CPU replacement happened.  Trust me, I happen to know one thing 
> or two about those issues you mentioned and the code I'm working on will 
> be posted in due course.

Stop being bitchy.  Look, the information I have on bigLittle is limited
to what has been discussed, and what is in the specs.  That's it.  I don't
know what the hell you're doing with this.  I'm not a part of that effort.
I'm totally out of the loop (as seems to be per bloody normal with ARM Ltd.)

So please don't expect me to know what you're working on, or how your code
works.  I don't.  I don't have that information.