[PATCH] drm/amdgpu: only use kernel zone if need_dma32 is not required

[Christian König]

Well that we evict here is perfectly intentional.

The laptop I'm typing on actually don't work without this, so please 
don't touch any of that.

Christian.

Am 12.06.19 um 20:06 schrieb Yang, Philip:
> That's kind of hack because dma32 zone is not needed, it has bad effect
> to trigger unnecessary eviction for KFDTest.BigBufStressTest. But
> ttm_bo_global_init->ttm_mem_global_init always create dma32 zone without
> accepting any parameter.
>
> To avoid ttm_mem_global_alloc_page account to dma32 zone, another option
> is to add a new flag to ttm_operation_ctx->flags, that looks not good
> either.
>
> Thanks,
> Philip
>
> On 2019-06-12 1:23 p.m., Kuehling, Felix wrote:
>> TTM itself has some logic for need_dma32 and TTM_PAGE_FLAG_DMA32. I
>> believe that should already handle this. need_dma32 is passed from
>> amdgpu to ttm_bo_device_init to bdev->need_dma32. ttm_tt_create
>> translates that to page_flags |= TTM_PAGE_FLAG_DMA32 and passes that to
>> bdev->driver->ttm_tt_create. The two page allocators in ttm_page_alloc.c
>> and ttm_page_alloc_dma.c check ttm->page_flags. Is that chain broken
>> somewhere? Overriding glob->mem_glob->num_zones from amdgpu seems to be
>> a bit of a hack.
>>
>> Regards,
>>      Felix
>>
>> On 2019-06-12 8:13, Yang, Philip wrote:
>>> TTM create two zones, kernel zone and dma32 zone for system memory. If
>>> system memory address allocated is below 4GB, this account to dma32 zone
>>> and will exhaust dma32 zone and trigger unnesssary TTM eviction.
>>>
>>> Patch "drm/ttm: Account for kernel allocations in kernel zone only" only
>>> handle the allocation for acc_size, the system memory page allocation is
>>> through ttm_mem_global_alloc_page which still account to dma32 zone if
>>> page is below 4GB.
>>>
>>> Change-Id: I289b85d891b8f64a1422c42b1eab398098ab7ef7
>>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>>> ---
>>>     drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 4 ++++
>>>     1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> index 2778ff63d97d..79bb9dfe617b 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> @@ -1686,6 +1686,10 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>>>     	}
>>>     	adev->mman.initialized = true;
>>>     
>>> +	/* Only kernel zone (no dma32 zone) if device does not require dma32 */
>>> +	if (!adev->need_dma32)
>>> +		adev->mman.bdev.glob->mem_glob->num_zones = 1;
>>> +
>>>     	/* We opt to avoid OOM on system pages allocations */
>>>     	adev->mman.bdev.no_retry = true;
>>>     
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