[PATCH 2/2] drm/amdgpu: remove extra placement for AMDGPU_GEM_CREATE_NO_CPU_ACCESS

[Christian König]

Hi David,

well that additional placement range actually caused a performance problem.

It's only effect is that we check the invisible space twice, which can 
burn quite a bunch of CPU cycles during allocation.

Can you somehow easily check for performance regressions?

Regards,
Christian.

Am 07.11.2016 um 03:35 schrieb zhoucm1:
> Hi Christian,
> I have some time not to track code, I'm not sure if I miss anything.
> In my mind, this change was added while doing performance 
> optimization. If you don't encounter any problem, I'm suggesting not 
> to change it, we have many regressions(bug and performance) recently.
>
> Regards,
> David Zhou
>
> On 2016年11月04日 19:00, Christian König wrote:
>> From: Christian König <christian.koenig at amd.com>
>>
>> This only has the effect of scanning the invisible range twice
>> since the topdown flag is given anyway.
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 -----------
>>   1 file changed, 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> index 6efa8d7..052c1b0 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> @@ -128,17 +128,6 @@ static void amdgpu_ttm_placement_init(struct 
>> amdgpu_device *adev,
>>           if (flags & AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS)
>>               lpfn = adev->mc.real_vram_size >> PAGE_SHIFT;
>>   -        if (flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS &&
>> -            !(flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) &&
>> -            adev->mc.visible_vram_size < adev->mc.real_vram_size) {
>> -            places[c].fpfn = visible_pfn;
>> -            places[c].lpfn = lpfn;
>> -            places[c].flags = TTM_PL_FLAG_WC |
>> -                TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_VRAM |
>> -                TTM_PL_FLAG_TOPDOWN;
>> -            c++;
>> -        }
>> -
>>           places[c].fpfn = 0;
>>           places[c].lpfn = lpfn;
>>           places[c].flags = TTM_PL_FLAG_WC | TTM_PL_FLAG_UNCACHED |
>