Re: [PATCH v9 10/15] x86/sgx: Add EPC reclamation in cgroup try_charge()

[Dave Hansen]

On 2/26/24 13:48, Haitao Huang wrote:
> In case of overcomitting, i.e., sum of limits greater than the EPC
> capacity, if one group has a fault, and its usage is not above its own
> limit (try_charge() passes), yet total usage of the system has exceeded
> the capacity, whether we do global reclaim or just reclaim pages in the
> current faulting group.

I don't see _any_ reason to limit reclaim to the current faulting cgroup.

>> Last, what is the simplest (least amount of code) thing that the SGX
>> cgroup controller could implement here?
> 
> I still think the current approach of doing global reclaim is reasonable
> and simple: try_charge() checks cgroup limit and reclaim within the
> group if needed, then do EPC page allocation, reclaim globally if
> allocation fails due to global usage reaches the capacity.
> 
> I'm not sure how not doing global reclaiming in this case would bring
> any benefit.
I tend to agree.

Kai, I think your examples sound a little bit contrived.  Have actual
users expressed a strong intent for doing anything with this series
other than limiting bad actors from eating all the EPC?