Re: [RFC V2 1/2] irq: Add a framework to measure interrupt timings

[Thomas Gleixner]

On Wed, 20 Jan 2016, Peter Zijlstra wrote:

> On Wed, Jan 20, 2016 at 08:57:06PM +0100, Thomas Gleixner wrote:
> > > Here too, ktime_get() is daft.
> > 
> > What's the problem? ktime_xxx() itself or just the clock monotonic variant?
> > 
> > On 99.9999% of the platforms ktime_get_mono_fast/raw_fast is not any slower
> > than sched_clock(). The only case where sched_clock is faster is if your TSC
> > is buggered and the box switches to HPET for timekeeping.
> 
> The HPET thing, I just don't want to have to explain why this is so much
> more expensive on some random weird machine, esp. since it really
> doesn't matter.

Fair enough.