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

[Thomas Gleixner]

Steven Rostedt <rostedt@xxxxxxxxxxx> writes:

> 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.

Gah. ktime_get_mono_fast_ns() and ktime_get() of course.