Re: [RFC PATCH v2 05/18] sched: add task flag for preempt IRQ tracking

[Jiri Kosina]

On Fri, 20 May 2016, Andy Lutomirski wrote:

> I think it would be negligible, at least for interrupts, since
> interrupts are already extremely expensive.  But I don't love adding
> assembly code that makes them even slower.  The real thing I dislike
> about this approach is that it's not a normal stack frame, so you need
> code in the unwinder to unwind through it correctly, which makes me
> think that you're not saving much complexity by adding the pushes.

I fail to see what is so special about the stack frame; it's in fact 
pretty normal.

It has added semantic value for "those who know", but the others will 
(pretty much correctly) consider it to be a stackframe from a function 
call, and be done with it.

What am I missing?

Thanks,

-- 
Jiri Kosina
SUSE Labs