Thread (43 messages) 43 messages, 7 authors, 2021-08-20

Re: [PATCH v6 05/13] drm/amdkfd: generic type as sys mem on migration to ram

From: Sierra Guiza, Alejandro (Alex) <hidden>
Date: 2021-08-16 19:53:25
Also in: amd-gfx, dri-devel, linux-mm, linux-xfs

On 8/15/2021 10:38 AM, Christoph Hellwig wrote:
On Fri, Aug 13, 2021 at 01:31:42AM -0500, Alex Sierra wrote:
quoted
  	migrate.vma = vma;
  	migrate.start = start;
  	migrate.end = end;
-	migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
  	migrate.pgmap_owner = SVM_ADEV_PGMAP_OWNER(adev);
  
+	if (adev->gmc.xgmi.connected_to_cpu)
+		migrate.flags = MIGRATE_VMA_SELECT_SYSTEM;
+	else
+		migrate.flags = MIGRATE_VMA_SELECT_DEVICE_PRIVATE;
It's been a while since I touched this migrate code, but doesn't this
mean that if the range already contains system memory the migration
now won't do anything? for the connected_to_cpu case?
For above’s condition equal to connected_to_cpu , we’re explicitly 
migrating from
device memory to system memory with device generic type. In this type, 
device PTEs are
present in CPU page table.

During migrate_vma_collect_pmd walk op at migrate_vma_setup call, 
there’s a condition
for present pte that require migrate->flags be set for 
MIGRATE_VMA_SELECT_SYSTEM.
Otherwise, the migration for this entry will be ignored.

Regards,
Alex S.
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