[PATCH] drm/amdgpu: improve GTT BO alloc speed in OGL

[Alex Deucher]

On Mon, Sep 12, 2016 at 2:26 PM, Christian König
<deathsimple at vodafone.de> wrote:
> Am 12.09.2016 um 18:44 schrieb Alex Deucher:
>>
>> From: "monk.liu" <monk.liu at amd.com>
>>
>> original we use ttm_dma path to allocate GTT bo, which is too much
>> slower than the path of ttm_pool, in most cases.
>>
>> The swiotlb checks don't seem to work and we always end up in the
>> slow path even when an IOMMU is available.
>
>
> While the check is clearly not correct. Simply always using the direct
> mapping and not checking the fallback path can break as well.
>
> So this patch is clearly not a good idea and needs to be fixed before it is
> pushed.

Jerome looked into it when Monk first debugged this, but I don't think
anything ever came of it:
https://patchwork.kernel.org/patch/7079521/

Alex

>
> Christian.
>
>
>> Signed-off-by: monk.liu <Monk.Liu at amd.com>
>> Reviewed-by: Jammy Zhou <jammy.zhou at amd.com>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 13 -------------
>>   1 file changed, 13 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 3beb10b..e2fcd39 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -783,12 +783,6 @@ static int amdgpu_ttm_tt_populate(struct ttm_tt *ttm)
>>         adev = amdgpu_get_adev(ttm->bdev);
>>   -#ifdef CONFIG_SWIOTLB
>> -       if (swiotlb_nr_tbl()) {
>> -               return ttm_dma_populate(&gtt->ttm, adev->dev);
>> -       }
>> -#endif
>> -
>>         r = ttm_pool_populate(ttm);
>>         if (r) {
>>                 return r;
>> @@ -829,13 +823,6 @@ static void amdgpu_ttm_tt_unpopulate(struct ttm_tt
>> *ttm)
>>         adev = amdgpu_get_adev(ttm->bdev);
>>   -#ifdef CONFIG_SWIOTLB
>> -       if (swiotlb_nr_tbl()) {
>> -               ttm_dma_unpopulate(&gtt->ttm, adev->dev);
>> -               return;
>> -       }
>> -#endif
>> -
>>         for (i = 0; i < ttm->num_pages; i++) {
>>                 if (gtt->ttm.dma_address[i]) {
>>                         pci_unmap_page(adev->pdev,
>> gtt->ttm.dma_address[i],
>
>
>