Am 03.07.2018 um 10:12 schrieb Zhang, Jerry (Junwei):
On 07/03/2018 02:58 PM, Christian König wrote:
Am 03.07.2018 um 03:59 schrieb Zhang, Jerry (Junwei):
On 07/02/2018 05:23 PM, Christian König wrote:
[SNIP]
The reservation_object_reserve_shared() function needs to be called
before you make submissions to the hardware to make sure that you
have a free slot after you made the submission.
The problem is now that we always reserve one free slot during
command submission, but for the page directory reservation object it
can happen that this free slot is used by VM updates.
So the safest approach is to make sure that we have another free slot
after the VM updates are done.
Michel's patch nearly did that, because we rarely have only one
submission in amdgpu_vm_update_directories(). But it isn't 100% correct.
Thanks to explain that, I think got your meaning that we should
reserve slot for command submission after VM update.
if so, shall we add reservation_object_reserve_shared() for both of
them, since any of place may run out of slot.
While the gap from me is I fail to find reserving slot during command
submission,
That's done by ttm_eu_reserve_buffers().
the root bo reservation seems to be used by VM update only(if not
correct me).
No, that is not correct. The root BO is also part of the list of BOs for
the command submission used by ttm_eu_reserve_buffers() and
ttm_eu_fence_buffer_objects().
All VM updates will use the same slot, so we just need one extra
reservation_object_reserve_shared() after all the VM updates are done.
Regards,
Christian.
command submission is likely to use bo's reservation from bo list
rather than root bo reservation.
BTW, reservation_object_reserve_shared() will extend the max num as 2
times if it's not enough.
(default value is 4)
Jerry
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