[Intel-gfx] [RFC 12/14] drm/i915: Interface for controling engine stats collection

[Tvrtko Ursulin]

On 19/07/2017 12:04, Chris Wilson wrote:

[snip]

>>> Long term though having a global static key is going to be a nasty wart.
>>> Joonas will definitely ask the question how much will it cost us to use
>>> an engine->bool and what we can do to minimise that cost.
>>
>> Why you think it is nasty? Sounds pretty cool to me.
> 
> If we enable sampling on one device (engine even!), it affects another.
> But the device is the more compelling argument against.

Since you mention engines, I can do it on engine granularity with normal 
branches. It makes sense for the pmu interface to have it per engine.

Then as I said before, I can put in a late patch in the series which 
adds a static key (master enable/disable on or-ed per-engine enables) 
just in case we find it attractive.

Regards,

Tvrtko