Re: [RFC 02/11] drm/i915: Add intel_energy_uJ

Chris Wilson
2017-09-15T10:38:28Z

Quoting Ville Syrjälä (2017-09-15 11:34:03)
> On Fri, Sep 15, 2017 at 11:07:21AM +0100, Tvrtko Ursulin wrote:
> >
> > On 15/09/2017 09:51, Chris Wilson wrote:
> > > Quoting Tvrtko Ursulin (2017-09-15 07:56:00)
> > >>
> > >> On 14/09/2017 21:36, Ville Syrjälä wrote:
> > >>> On Mon, Sep 11, 2017 at 04:25:50PM +0100, Tvrtko Ursulin wrote:
> > >>>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > >>>>
> > >>>> Extract code from i915_energy_uJ (debugfs) so it can be used by
> > >>>> other callers in future patches.
> > >>>>
> > >>>> v2: Rebase.
> > >>>>
> > >>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > >>>> ---
> > >>>> drivers/gpu/drm/i915/i915_debugfs.c | 17 +----------------
> > >>>> drivers/gpu/drm/i915/i915_drv.h | 2 ++
> > >>>> drivers/gpu/drm/i915/intel_pm.c | 25 +++++++++++++++++++++++++
> > >>>> 3 files changed, 28 insertions(+), 16 deletions(-)
> > >>>>
> > >>>> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > >>>> index 6338018f655d..b3a4a66bf7c4 100644
> > >>>> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > >>>> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > >>>> @@ -2780,26 +2780,11 @@ static int i915_sink_crc(struct seq_file *m, void *data)
> > >>>> static int i915_energy_uJ(struct seq_file *m, void *data)
> > >>>> {
> > >>>> struct drm_i915_private *dev_priv = node_to_i915(m->private);
> > >>>> - unsigned long long power;
> > >>>> - u32 units;
> > >>>>
> > >>>> if (INTEL_GEN(dev_priv) < 6)
> > >>>> return -ENODEV;
> > >>>>
> > >>>> - intel_runtime_pm_get(dev_priv);
> > >>>> -
> > >>>> - if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &power)) {
> > >>>> - intel_runtime_pm_put(dev_priv);
> > >>>> - return -ENODEV;
> > >>>> - }
> > >>>> -
> > >>>> - units = (power & 0x1f00) >> 8;
> > >>>> - power = I915_READ(MCH_SECP_NRG_STTS);
> > >>>> - power = (1000000 * power) >> units; /* convert to uJ */
> > >>>> -
> > >>>> - intel_runtime_pm_put(dev_priv);
> > >>>> -
> > >>>> - seq_printf(m, "%llu", power);
> > >>>> + seq_printf(m, "%llu", intel_energy_uJ(dev_priv));
> > >>>
> > >>> Isn't this the same thing as the package energy you get from rapl? Can't
> > >>> we just nuke this private implementation entirely and rely on whatever
> > >>> rapl gives us?
> > >>
> > >> If so I think we could leave it out of i915 PMU. I tried looking for
> > >> MCH_SECP_NRG_STTS in bspec but did not find it though? Is your bspec fu
> > >> perhaps better and you could have a look?
> > >
> > > I had it there for the convenience of grabbing everything through the
> > > one interface (which I still think has merit). I don't I ever compiled
> > > in the rapl user interface...
> >
> > You mean the RAPL PMU, PERF_EVENTS_INTEL_RAPL?
>
> I suspect he means sysfs. IIRC this perf+rapl marriage is somewhat
> recent (or at least I still remeber having to fix it when it was
> introduced because it broke the sysfs interface).

I hadn't even heard of the perf interface. Yes, if it is available
through perf, that's just what we want.
-Chris