[PATCH 1/8] drm/amdgpu: make VMID assignment more fair

[Christian König]

> reserved vmid is independent on id_mgr
And that is exactly the reason why I want to have that here.

If we don't fix this reserving a VMID would otherwise give the process 
an unfair advantage while scheduling jobs.

Regards,
Christian.

Am 01.02.2018 um 05:42 schrieb Chunming Zhou:
> NAK, reserved vmid is independent on id_mgr, which is removed from id 
> mgr when process allocates reserved vmid.
>
>
> Regards,
>
> David Zhou
>
>
> On 2018年01月31日 23:47, Christian König wrote:
>> To guarantee fairness between processes grab reserved VMID only when
>> there is an idle one.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c | 12 +++++++-----
>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
>> index c13cf7e79b2e..7a3d0de7425d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
>> @@ -268,11 +268,6 @@ int amdgpu_vmid_grab(struct amdgpu_vm *vm, 
>> struct amdgpu_ring *ring,
>>       int r = 0;
>>         mutex_lock(&id_mgr->lock);
>> -    if (vm->reserved_vmid[vmhub]) {
>> -        r = amdgpu_vmid_grab_reserved_locked(vm, ring, sync, fence, 
>> job);
>> -        mutex_unlock(&id_mgr->lock);
>> -        return r;
>> -    }
>>       fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, 
>> GFP_KERNEL);
>>       if (!fences) {
>>           mutex_unlock(&id_mgr->lock);
>> @@ -319,6 +314,13 @@ int amdgpu_vmid_grab(struct amdgpu_vm *vm, 
>> struct amdgpu_ring *ring,
>>       }
>>       kfree(fences);
>>   +    if (vm->reserved_vmid[vmhub]) {
>> +        r = amdgpu_vmid_grab_reserved_locked(vm, ring, sync,
>> +                             fence, job);
>> +        mutex_unlock(&id_mgr->lock);
>> +        return r;
>> +    }
>> +
>>       job->vm_needs_flush = vm->use_cpu_for_update;
>>       /* Check if we can use a VMID already assigned to this VM */
>>       list_for_each_entry_reverse(id, &id_mgr->ids_lru, list) {
>