Re: [PATCH 13/15] drm/amdgpu: adapt vm size for multi vmpt

[Christian König]

Am 28.03.2017 um 05:19 schrieb Zhang, Jerry (Junwei):

On 03/27/2017 01:53 PM, Chunming Zhou wrote:

Change-Id: I17b40aec68404e46961a9fda22dfadd1ae9d6f2c
Signed-off-by: Chunming Zhou 
---
  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 6 ++
  1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c 
b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

index 6625a2f..613c8f6 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -508,6 +508,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device 
*adev)

   * amdkfd will use VMIDs 8-15
   */
  adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
+/* Because of four level VMPTs, vm size at least is 256GB.
+256TB is OK as well */


If each PT size is 9, and contains 3 levels PT + 1 PD.
9 * 3 + 12(page size) + 1(at least 1 bit for PD) = 40 bits here.

Then it looks 1T is minimum size.
Please confirm it.


I would rather say completely ignore the setting of amdgpu_vm_size here 
and always use 256TB for GFX9.


Allocating a PD smaller than 4K doesn't make much sense cause you don't 
save anything.


So the only valid approach would be to switch between 1, 2, 3 and 4 
levels when the VM size changes and that doesn't make to much sense to 
me because the saved memory is minimal (4K for each level).


Christian.



Jerry.


+if (amdgpu_vm_size < 256) {
+DRM_WARN("vm size at least is 256GB!\n");
+amdgpu_vm_size = 256;
+}
  adev->vm_manager.num_level = 1;
  amdgpu_vm_manager_init(adev);



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Re: [PATCH 13/15] drm/amdgpu: adapt vm size for multi vmpt

[zhoucm1]

On 2017年03月28日 11:19, Zhang, Jerry (Junwei) wrote:

On 03/27/2017 01:53 PM, Chunming Zhou wrote:

Change-Id: I17b40aec68404e46961a9fda22dfadd1ae9d6f2c
Signed-off-by: Chunming Zhou 
---
  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 6 ++
  1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c 
b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

index 6625a2f..613c8f6 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -508,6 +508,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device 
*adev)

   * amdkfd will use VMIDs 8-15
   */
  adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
+/* Because of four level VMPTs, vm size at least is 256GB.
+256TB is OK as well */


If each PT size is 9, and contains 3 levels PT + 1 PD.
9 * 3 + 12(page size) + 1(at least 1 bit for PD) = 40 bits here.
block size is 9 means 512 entries each PDB/PTB. then one PDE of 4 levels 
is 512* 512 *512*4KB = 512GB.


will send another patch to correct this typo.

Thanks,
David Zhou


Then it looks 1T is minimum size.
Please confirm it.

Jerry.


+if (amdgpu_vm_size < 256) {
+DRM_WARN("vm size at least is 256GB!\n");
+amdgpu_vm_size = 256;
+}
  adev->vm_manager.num_level = 1;
  amdgpu_vm_manager_init(adev);




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Re: [PATCH 13/15] drm/amdgpu: adapt vm size for multi vmpt

[Zhang, Jerry (Junwei)]

On 03/27/2017 01:53 PM, Chunming Zhou wrote:

Change-Id: I17b40aec68404e46961a9fda22dfadd1ae9d6f2c
Signed-off-by: Chunming Zhou 
---
  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 6 ++
  1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c 
b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index 6625a2f..613c8f6 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -508,6 +508,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device *adev)
 * amdkfd will use VMIDs 8-15
 */
adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
+   /* Because of four level VMPTs, vm size at least is 256GB.
+   256TB is OK as well */


If each PT size is 9, and contains 3 levels PT + 1 PD.
9 * 3 + 12(page size) + 1(at least 1 bit for PD) = 40 bits here.

Then it looks 1T is minimum size.
Please confirm it.

Jerry.


+   if (amdgpu_vm_size < 256) {
+   DRM_WARN("vm size at least is 256GB!\n");
+   amdgpu_vm_size = 256;
+   }
adev->vm_manager.num_level = 1;
amdgpu_vm_manager_init(adev);



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[PATCH 13/15] drm/amdgpu: adapt vm size for multi vmpt

[Chunming Zhou]

Change-Id: I17b40aec68404e46961a9fda22dfadd1ae9d6f2c
Signed-off-by: Chunming Zhou 
---
 drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 6 ++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c 
b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
index 6625a2f..613c8f6 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
@@ -508,6 +508,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device *adev)
 * amdkfd will use VMIDs 8-15
 */
adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
+   /* Because of four level VMPTs, vm size at least is 256GB.
+   256TB is OK as well */
+   if (amdgpu_vm_size < 256) {
+   DRM_WARN("vm size at least is 256GB!\n");
+   amdgpu_vm_size = 256;
+   }
adev->vm_manager.num_level = 1;
amdgpu_vm_manager_init(adev);
 
-- 
1.9.1

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