Re: [PATCH 2/2] drm/amdgpu: Let KFD use more VMIDs on Arcturus

["Christian König" <christian.koenig@amd.com>]

Am 25.06.20 um 17:15 schrieb Felix Kuehling:
> Am 2020-06-25 um 4:19 a.m. schrieb Christian König:
>> Am 25.06.20 um 05:18 schrieb Felix Kuehling:
>>> When there is no graphics support, KFD can use more of the VMIDs.
>>> Graphics
>>> VMIDs are only used for video decoding/encoding and post processing.
>>> With
>>> two VCE engines, there is no reason to reserve more than 2 VMIDs for
>>> that.
>> IIRC the expectation is that we still use the compute queues for post
>> processing and not the KFD.
>>
>> So we will need at least VMIDs for that as well.
> Correct. Post processing uses compute queues and VMIDs in the GFXHUB.
> VCE uses VMIDs in the MMHUB. I believe in Mesa they use the same VM
> context. So can't they share the same VMIDs?

Ah! Good point, But we still need at least 3 VMID when VMID reservation 
is active.

I don't think you can go below this.

Regards,
Christian.

>
> Regards,
>    Felix
>
>
>>> Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 11 ++++++++---
>>>    1 file changed, 8 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> index 6e10b42c57e5..3470929e5b8e 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
>>> @@ -1245,10 +1245,15 @@ static int gmc_v9_0_sw_init(void *handle)
>>>        /*
>>>         * number of VMs
>>>         * VMID 0 is reserved for System
>>> -     * amdgpu graphics/compute will use VMIDs 1-7
>>> -     * amdkfd will use VMIDs 8-15
>>> +     * amdgpu graphics/compute will use VMIDs 1..n-1
>>> +     * amdkfd will use VMIDs n..15
>>> +     *
>>> +     * The first KFD VMID is 8 for GPUs with graphics, 3 for
>>> +     * compute-only GPUs. On compute-only GPUs that leaves 2 VMIDs
>>> +     * for video processing.
>>>         */
>>> -    adev->vm_manager.first_kfd_vmid = 8;
>>> +    adev->vm_manager.first_kfd_vmid =
>>> +        adev->asic_type == CHIP_ARCTURUS ? 3 : 8;
>>>          amdgpu_vm_manager_init(adev);
>>>    

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