Re: [PATCH 5/5] drm/i915/pmu: Support multiple GPUs

From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 5/5] drm/i915/pmu: Support multiple GPUs
Date: Thu, 1 Aug 2019 16:10:14 +0100	[thread overview]
Message-ID: <6e776f39-efba-08bc-e96d-188cc88ebcb4@linux.intel.com> (raw)
In-Reply-To: <156467129926.6045.16909307069650415218@skylake-alporthouse-com>

On 01/08/2019 15:54, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-08-01 15:17:32)
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> With discrete graphics system can have both integrated and discrete GPU
>> handled by i915.
>>
>> Currently we use a fixed name ("i915") when registering as the uncore PMU
>> provider which stops working in this case.
>>
>> To fix this we add the PCI device name string to non-integrated devices
>> handled by us. Integrated devices keep the legacy name preserving
>> backward compatibility.
>>
>> v2:
>>   * Detect IGP and keep legacy name. (Michal)
>>   * Use PCI device name as suffix. (Michal, Chris)
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> ---
>> Is our GPU always "0000:00:02.0"? CI will tell me.
> 
> It always has been. (With a few additional 2.1 for Windows95 multihead
> where each head had to be a unique device!)
> 
> One hopes that by now it is firmly ingrained that it will always be
> kept to 00:02.0.

Re-assuring, thanks! However still some tests to do before I am happy 
this is upstream worthy, not least CI.

> 
>> ---
>>   drivers/gpu/drm/i915/i915_pmu.c | 27 +++++++++++++++++++++++++--
>>   drivers/gpu/drm/i915/i915_pmu.h |  4 ++++
>>   2 files changed, 29 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
>> index e0e0180bca7c..9a404d85c4e9 100644
>> --- a/drivers/gpu/drm/i915/i915_pmu.c
>> +++ b/drivers/gpu/drm/i915/i915_pmu.c
>> @@ -1053,6 +1053,15 @@ static void i915_pmu_unregister_cpuhp_state(struct i915_pmu *pmu)
>>          cpuhp_remove_multi_state(cpuhp_slot);
>>   }
>>   
>> +static bool is_igp(struct pci_dev *pdev)
>> +{
>> +       /* IGP is 0000:00:02.0 */
>> +       return pdev->bus->parent == NULL &&
> 
> pci_domain_nr(pdev->bus) == 0 ?

Aha, thanks!

> 
>> +              pdev->bus->number == 0 &&
>> +              PCI_SLOT(pdev->devfn) == 2 &&
>> +              PCI_FUNC(pdev->devfn) == 0;
> 
> I am surprised there isn't already a convenience function. None that I
> could find.
> 
>> +}
>> +
>>   void i915_pmu_register(struct drm_i915_private *i915)
>>   {
>>          struct i915_pmu *pmu = &i915->pmu;
>> @@ -1083,10 +1092,19 @@ void i915_pmu_register(struct drm_i915_private *i915)
>>          hrtimer_init(&pmu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>>          pmu->timer.function = i915_sample;
>>   
>> -       ret = perf_pmu_register(&pmu->base, "i915", -1);
>> -       if (ret)
>> +       if (!is_igp(i915->drm.pdev))
>> +               pmu->name = kasprintf(GFP_KERNEL,
>> +                                     "i915-%s",
>> +                                     dev_name(i915->drm.dev));
>> +       else
>> +               pmu->name = "i915";
> 
> Makes sense, and quite a neat solution.
> 
>> +       if (!pmu->name)
>>                  goto err;
>>   
>> +       ret = perf_pmu_register(&pmu->base, pmu->name, -1);
>> +       if (ret)
>> +               goto err_name;
>> +
>>          ret = i915_pmu_register_cpuhp_state(pmu);
>>          if (ret)
>>                  goto err_unreg;
>> @@ -1095,6 +1113,9 @@ void i915_pmu_register(struct drm_i915_private *i915)
>>   
>>   err_unreg:
>>          perf_pmu_unregister(&pmu->base);
>> +err_name:
>> +       if (!is_igp(i915->drm.pdev))
>> +               kfree(pmu->name);
> kfree_const(pmu->name);
> 
>>   err:
>>          pmu->base.event_init = NULL;
>>          free_event_attributes(pmu);
>> @@ -1116,5 +1137,7 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
>>   
>>          perf_pmu_unregister(&pmu->base);
>>          pmu->base.event_init = NULL;
>> +       if (!is_igp(i915->drm.pdev))
>> +               kfree(pmu->name);
> 
> kfree_const(pmu->name);
> 
> Works for me, I wonder what PeterZ will say...

In what sense?

> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Thanks,

Tvrtko

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