[Intel-gfx] [PATCH 7/9] drm/i915/perf: Allow dynamic reconfiguration of the OA stream

[Lionel Landwerlin]

On 10/10/2019 18:44, Chris Wilson wrote:
> Quoting Lionel Landwerlin (2019-10-10 16:22:25)
>> On 10/10/2019 00:19, Chris Wilson wrote:
>>> From: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>>
>>> Introduce a new perf_ioctl command to change the OA configuration of the
>>> active stream. This allows the OA stream to be reconfigured between
>>> batch buffers, giving greater flexibility in sampling. We inject a
>>> request into the OA context to reconfigure the stream asynchronously on
>>> the GPU in between and ordered with execbuffer calls.
>>>
>>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
>>
>> So much simpler :)
> Indeed, it all came together into a much more coherent story.
>
>>> ---
>>>    /**
>>>     * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
>>>     * @stream: An i915 perf stream
>>> @@ -2879,6 +2901,8 @@ static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
>>>        case I915_PERF_IOCTL_DISABLE:
>>>                i915_perf_disable_locked(stream);
>>>                return 0;
>>> +     case I915_PERF_IOCTL_CONFIG:
>>> +             return i915_perf_config_locked(stream, arg);
>> For REMOVE_CONFIG we passed a pointer to an u64, not sure whether we
>> should reuse the same pattern here?
> Aiui, the user creates oa-config handles, and/or queries them. If we are
> simpler talking handles that fit inside unsigned long (so assume u32)
> then I don't see the harm in passing an id rather than a pointer.
>
> The alternative is this takes an uuid string? Or you want to always use
> u64 handles?
>
> I guess you will have a better idea what works better after playing
> around with userspace.
> -Chris
>
Yeah, that's a fine interface actually.

This should really have you as the author.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>