[Intel-gfx] [PATCH] drm/i915: add a tracepoint for gpu frequency changes

[Daniel Vetter]

On Sat, Sep 1, 2012 at 8:35 PM, Ben Widawsky <ben at bwidawsk.net> wrote:
> On 2012-09-01 11:28, Arjan van de Ven wrote:
>>
>> On 9/1/2012 11:26 AM, Ben Widawsky wrote:
>>>
>>> On 2012-08-30 04:26, Daniel Vetter wrote:
>>>>
>>>> We've had and still have too many issues where the gpu turbot doesn't
>>>> quite to what it's supposed to do (or what we want it to do).
>>>>
>>>> Adding a tracepoint to track when the desired gpu frequence changes
>>>> should help a lot in characterizing and understanding problematic
>>>> workloads.
>>>>
>>>> Also, this should be fairly interesting for power tuning (and
>>>> especially noticing when the gpu is stuck in high frequencies, as has
>>>> happened in the past) and hence for integration into powertop and
>>>> similar tools.
>>>>
>>>> Cc: Arjan van de Ven <arjan at linux.intel.com>
>>>> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>>>
>>>
>>> I can't help but think it's equally interesting to know when the queue
>>> the work as well.
>>>
>>>
>>
>> btw... if the userspace interface (e.g. the actual event) is not
>> controversial and very unlikely to change,
>> I'd like to start coding the powertop support for this already....
>
>
> I have no problem with Daniel's patch. It's just a matter of cutting through
> some scheduler BS of "when the GPU wants to change frequency" vs. "when we
> actually change the GPU frequency." I think *both* are interesting.

Hm, aren't there some neat tracepoints to measure the latency of work
items around already? I agree that this might be useful, but just
adding a tracepoint for this one workqueue item feels like overkill
...

Arjan, the tracepoint patch is merged already into
drm-intel-next-queued, i.e. powertop integration is good to go.

Thanks, Daniel
-- 
Daniel Vetter
daniel.vetter at ffwll.ch - +41 (0) 79 365 57 48 - http://blog.ffwll.ch