Re: [patch V6 01/37] tracing/hwlat: Use ktime_get_mono_fast_ns()

[Steven Rostedt]

On Tue, 19 May 2020 23:45:10 +0200
Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:

> >> @@ -165,20 +155,22 @@ void trace_hwlat_callback(bool enter)
> >>   * Used to repeatedly capture the CPU TSC (or similar), looking for potential
> >>   * hardware-induced latency. Called with interrupts disabled and with
> >>   * hwlat_data.lock held.
> >> + *
> >> + * Use ktime_get_mono_fast() here as well because it does not wait on the
> >> + * timekeeping seqcount like ktime_get_mono().  
> >
> > When doing a "git grep ktime_get_mono" I only find
> > ktime_get_mono_fast_ns() (and this comment), so I don't know what to compare
> > that to. Did you mean another function?  
> 
> Yeah. I fatfingered the comment. The code uses ktime_get_mono_fast_ns().

Well, I assumed that's what you meant with "ktime_get_mono_fast()" but I
don't know what function you are comparing it to that waits on the seqcount
like "ktime_get_mono()" as there is no such function.

-- Steve