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

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

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?

If it provides the same thing, and in fact even more different counters 
than this RFC, then I think it is not that much more difficult to use 
two PMUs from things like intel-gpu-overlay or something.

Regards,

Tvrtko
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