On Tue, Mar 29, 2022 at 9:59 AM Tejun Heo tj@kernel.org wrote:
Hello,
I'm sorry for the delay Tejun, my test device stopped working and my attention has been occupied with that.
On Mon, Mar 28, 2022 at 03:59:41AM +0000, T.J. Mercier wrote:
The API/UAPI can be extended to set per-device/total allocation limits in the future.
This total thing kinda bothers me. Can you please provide some concrete examples of how this and per-device limits would be used?
The use case we have for accounting the total (separate from the individual devices) is to include the value as part of bugreports, for understanding the system-wide amount of dmabuf allocations. I'm not aware of an existing need to limit the total. Admittedly this is just the sum over the devices, but we currently maintain out of tree code to do this sort of thing today. [1]
The per-device limits would be used to restrict the amount of each type of allocation charged to an individual application to prevent hogging or to completely prevent access. This limitation is not something we have implemented today, but it is on our roadmap.
[1] https://android-review.googlesource.com/c/kernel/common/+/1566704/3/drivers/...
Thanks.
-- tejun