On 7/15/20 1:51 PM, Chris Wilson wrote:
It is reasonably common for userspace (even modern drivers like iris) to
reuse an active address for a new buffer. This would cause the
application to stall under its mutex (originally struct_mutex) until the
old batches were idle and it could synchronously remove the stale PTE.
However, we can queue up a job that waits on the signal for the old
nodes to complete and upon those signals, remove the old nodes replacing
them with the new ones for the batch. This is still CPU driven, but in
theory we can do the GTT patching from the GPU. The job itself has a
completion signal allowing the execbuf to wait upon the rebinding, and
also other observers to coordinate with the common VM activity.
Letting userspace queue up more work, lets it do more stuff without
blocking other clients. In turn, we take care not to let it too much
concurrent work, creating a small number of queues for each context to
limit the number of concurrent tasks.
The implementation relies on only scheduling one unbind operation per
vma as we use the unbound vma->node location to track the stale PTE.
Closes: https://gitlab.freedesktop.org/drm/intel/issues/1402
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.a...@intel.com>
Cc: Andi Shyti <andi.sh...@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellst...@intel.com>
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
