Re: [RFC PATCH 00/20] Add Cgroup support for SGX EPC memory

[Jarkko Sakkinen]

On Thu, Sep 22, 2022 at 10:10:37AM -0700, Kristen Carlson Accardi wrote:
> Add a new cgroup controller to regulate the distribution of SGX EPC memory,
> which is a subset of system RAM that is used to provide SGX-enabled
> applications with protected memory, and is otherwise inaccessible.
> 
> SGX EPC memory allocations are separate from normal RAM allocations,
> and is managed solely by the SGX subsystem. The existing cgroup memory
> controller cannot be used to limit or account for SGX EPC memory.
> 
> This patchset implements the sgx_epc cgroup controller, which will provide
> support for stats, events, and the following interface files:
> 
> sgx_epc.current
> 	A read-only value which represents the total amount of EPC
> 	memory currently being used on by the cgroup and its descendents.
> 
> sgx_epc.low
> 	A read-write value which is used to set best-effort protection
> 	of EPC usage. If the EPC usage of a cgroup drops below this value,
> 	then the cgroup's EPC memory will not be reclaimed if possible.
> 
> sgx_epc.high
> 	A read-write value which is used to set a best-effort limit
> 	on the amount of EPC usage a cgroup has. If a cgroup's usage
> 	goes past the high value, the EPC memory of that cgroup will
> 	get reclaimed back under the high limit.
> 
> sgx_epc.max
> 	A read-write value which is used to set a hard limit for
> 	cgroup EPC usage. If a cgroup's EPC usage reaches this limit,
> 	allocations are blocked until EPC memory can be reclaimed from
> 	the cgroup.

It would be worth of mentioning for clarity that shmem is accounted from
memcg.

BR, Jarkko