Re: [Intel-gfx] [PATCH] drm/i915/pmu: "Frequency" is reported as accumulated cycles

[Chris Wilson <chris@chris-wilson.co.uk>]

Quoting Tvrtko Ursulin (2019-11-11 09:11:03)
> 
> On 09/11/2019 10:53, Chris Wilson wrote:
> > We report "frequencies" (actual-frequency, requested-frequency) as the
> > number of accumulated cycles so that the average frequency over that
> > period may be determined by the user. This means the units we report to
> > the user are Mcycles (or just M), not MHz.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > Cc: stable@vger.kernel.org
> > ---
> >   drivers/gpu/drm/i915/i915_pmu.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> > index 4804775644bf..9b02be0ad4e6 100644
> > --- a/drivers/gpu/drm/i915/i915_pmu.c
> > +++ b/drivers/gpu/drm/i915/i915_pmu.c
> > @@ -908,8 +908,8 @@ create_event_attributes(struct i915_pmu *pmu)
> >               const char *name;
> >               const char *unit;
> >       } events[] = {
> > -             __event(I915_PMU_ACTUAL_FREQUENCY, "actual-frequency", "MHz"),
> > -             __event(I915_PMU_REQUESTED_FREQUENCY, "requested-frequency", "MHz"),
> > +             __event(I915_PMU_ACTUAL_FREQUENCY, "actual-frequency", "M"),
> > +             __event(I915_PMU_REQUESTED_FREQUENCY, "requested-frequency", "M"),
> >               __event(I915_PMU_INTERRUPTS, "interrupts", NULL),
> >               __event(I915_PMU_RC6_RESIDENCY, "rc6-residency", "ns"),
> >       };
> > 
> 
> MHz was wrong yes. But is 'M' established or would 'Mcycles' be better?

The only place where "cycles" pops up is in the perf ui, the other
events that I thought were similar in nature are unitless. As the
'cycle' itself is not an SI base unit as it is a mere count.

~o~ I have no idea ~o~
-Chris