Am 11.05.21 um 16:06 schrieb Thomas Hellström (Intel):
On 5/11/21 3:58 PM, Christian König wrote:
Am 11.05.21 um 15:25 schrieb Thomas Hellström:
Most logical place to introduce TTM buffer objects is as an i915
gem object backend. We need to add some ops to account for added
functionality like delayed delete and LRU list manipulation.
Initially we support only LMEM and SYSTEM memory, but SYSTEM
(which in this case means evicted LMEM objects) is not
visible to i915 GEM yet. The plan is to move the i915 gem system region
over to the TTM system memory type in upcoming patches.
We set up GPU bindings directly both from LMEM and from the system
region,
as there is no need to use the legacy TTM_TT memory type. We reserve
that for future porting of GGTT bindings to TTM.
There are some changes to TTM to allow for purging system memory buffer
objects and to refuse swapping of some objects: Unfortunately i915 gem
still relies heavily on short-term object pinning, and we've chosen to
keep short-term-pinned buffer objects on the TTM LRU lists for now,
meaning that we need some sort of mechanism to tell TTM they are not
swappable. A longer term goal is to get rid of the short-term pinning.
Well just use the eviction_valuable interface for this.
Yes, we do that for vram/lmem eviction, but we have nothing similar
for system swapping. Do I understand you correctly that you want me to
add a call to eviction_valuable() also for that instead of
swap_possible()?
You should already have that. eviction_valuable is called in both cases.
In general please make separate patches for the TTM changes and for
the i915 changes using them for easier review.
I'll respin with a split. Do you want me to do the same also for the
other two patches that minmally touch TTM?
Yes, that makes it much easier to review the general usefulness of
interface changes.
Thanks,
Christian.
Thanks,
Thomas
