Re: [PATCH v5 4/4] drm/amdgpu: track bo memory stats at runtime

["Christian König" <christian.koenig@amd.com>]

Am 22.10.24 um 18:46 schrieb Li, Yunxiang (Teddy):
> [Public]
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> I suppose we could add a field like amd-memory-private: to cover the private placements.

No, that is not really appropriate either. GWS, GDS and OA are not 
memory in the first place.

Those BOs are HW blocks which the driver allocated to use.

So accounting them for the memory usage doesn't make any sense at all.

We could print them in the fdinfo as something special for statistics, 
but it's probably not that useful.

>   When would a BO not have a placement, is it when it is being moved?

There are BOs which are only temporary, so when they are evicted their 
backing store is just discarded.

Additional to that allocation of backing store is sometimes delayed 
until the first use.

>   Since we are tracking the state changes, I wonder if such situations can be avoided now so whenever we call these stat update functions the BO would always have a placement.

No, as I said before those use cases are perfectly valid. BO don't need 
a backing store nor do they need a placement.

So the code has to gracefully handle that.

Regards,
Christian.

>
> Teddy