On 5/18/21 10:26 AM, Thomas Hellström wrote:
We are calling the eviction_valuable driver callback at eviction time to
determine whether we actually can evict a buffer object.
The upcoming i915 TTM backend needs the same functionality for swapout,
and that might actually be beneficial to other drivers as well.
Add an eviction_valuable call also in the swapout path. Try to keep the
current behaviour for all drivers by returning true if the buffer object
is already in the TTM_PL_SYSTEM placement. We change behaviour for the
case where a buffer object is in a TT backed placement when swapped out,
in which case the drivers normal eviction_valuable path is run.
Finally export ttm_tt_unpopulate() and don't swap out bos
that are not populated. This allows a driver to purge a bo at
swapout time if its content is no longer valuable rather than to
have TTM swap the contents out.
Cc: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Christian,
Here we have a ttm_tt_unpopulate() export as well at the end. I figure
you will push back on that one. What we really need is a functionality
to just drop the bo contents and end up in system memory unpopulated.
Should I perhaps add a utility function to do that instead? like
ttm_bo_purge()?
Thanks,
Thomas
