[PATCH v2 1/5] drm/amdgpu: add UAPI for workload hints to ctx ioctl

[Christian König]

Am 26.09.22 um 17:14 schrieb Sharma, Shashank:
>
> Hello Christian,
>
> On 9/26/2022 5:10 PM, Christian König wrote:
>> Am 26.09.22 um 17:02 schrieb Shashank Sharma:
>>> Allow the user to specify a workload hint to the kernel.
>>> We can use these to tweak the dpm heuristics to better match
>>> the workload for improved performance.
>>>
>>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>>> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
>>> ---
>>>   include/uapi/drm/amdgpu_drm.h | 18 ++++++++++++++++++
>>>   1 file changed, 18 insertions(+)
>>>
>>> diff --git a/include/uapi/drm/amdgpu_drm.h 
>>> b/include/uapi/drm/amdgpu_drm.h
>>> index c2c9c674a223..da5019a6e233 100644
>>> --- a/include/uapi/drm/amdgpu_drm.h
>>> +++ b/include/uapi/drm/amdgpu_drm.h
>>> @@ -212,6 +212,8 @@ union drm_amdgpu_bo_list {
>>>   #define AMDGPU_CTX_OP_QUERY_STATE2    4
>>>   #define AMDGPU_CTX_OP_GET_STABLE_PSTATE    5
>>>   #define AMDGPU_CTX_OP_SET_STABLE_PSTATE    6
>>> +#define AMDGPU_CTX_OP_GET_WORKLOAD_PROFILE    7
>>
>> Do we really have an use case for getting the profile or is that just 
>> added for completeness?
>> To be honest, there is no direct use case for a get(). We have 
> self-reset in kernel to clear the profile, so this is just for the 
> sake of completeness.

The problem is we usually need an userspace use case to justify 
upstreaming of an UAPI.

We already had a couple of cases where we only upstreamed UAPI for the 
sake of completeness (set/get pair for example) and then years later 
found out that the getter is completely broken for years because nobody 
used it.

So if we don't really need it I would try to avoid it.

Christian.

>
>> At base minimum we need a test-case for both to exercise the UAPI.
>>
>
> Agree, I have already added some test cases in libdrm/tests/amdgpu for 
> my local testing, I will start publishing them once we have an 
> agreement on the UAPI and kernel design.
>
> - Shashank
>
>> Regards,
>> Christian.
>>
>>> +#define AMDGPU_CTX_OP_SET_WORKLOAD_PROFILE    8
>>>   /* GPU reset status */
>>>   #define AMDGPU_CTX_NO_RESET        0
>>> @@ -252,6 +254,17 @@ union drm_amdgpu_bo_list {
>>>   #define AMDGPU_CTX_STABLE_PSTATE_MIN_MCLK  3
>>>   #define AMDGPU_CTX_STABLE_PSTATE_PEAK  4
>>> +/* GPU workload hints, flag bits 8-15 */
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_SHIFT     8
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_MASK      (0xff << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_NONE      (0 << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_3D        (1 << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_VIDEO     (2 << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_VR        (3 << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_COMPUTE   (4 << 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +#define AMDGPU_CTX_WORKLOAD_HINT_MAX AMDGPU_CTX_WORKLOAD_HINT_COMPUTE
>>> +#define AMDGPU_CTX_WORKLOAD_INDEX(n)       (n >> 
>>> AMDGPU_CTX_WORKLOAD_HINT_SHIFT)
>>> +
>>>   struct drm_amdgpu_ctx_in {
>>>       /** AMDGPU_CTX_OP_* */
>>>       __u32    op;
>>> @@ -281,6 +294,11 @@ union drm_amdgpu_ctx_out {
>>>               __u32    flags;
>>>               __u32    _pad;
>>>           } pstate;
>>> +
>>> +        struct {
>>> +            __u32    flags;
>>> +            __u32    _pad;
>>> +        } workload;
>>>   };
>>>   union drm_amdgpu_ctx {
>>