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

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Date:   Thu, 22 Sep 2022 14:03:52 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Tejun Heo <tj@...nel.org>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org,
        cgroups@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <songmuchun@...edance.com>
Subject: Re: [RFC PATCH 00/20] Add Cgroup support for SGX EPC memory

On 9/22/22 12:08, Tejun Heo wrote:
> Can you please give more concrete examples? I'd love to hear how the SGX EPC
> memory is typically used in what amounts and what's the performance
> implications when they get reclaimed and so on. ie. Please describe a
> realistic usage scenario of contention with sufficient details on how the
> system is set up, what the applications are using the SGX EPC memory for and
> how much, how the contention on memory affects the users and so on.

One wrinkle is that the apps that use SGX EPC memory are *normal* apps.
 There are frameworks that some folks are very excited about that allow
you to run mostly unmodified app stacks inside SGX.  For example:

	https://github.com/gramineproject/graphene

In fact, Gramine users are the troublesome ones for overcommit.  Most
explicitly-written SGX applications are quite austere in their SGX
memory use; they're probably never going to see overcommit.  These
Gramine-wrapped apps are (relative) pigs.  They've been the ones finding
bugs in the existing SGX overcommit code.

So, where does all the SGX memory go?  It's the usual suspects:
memcached and redis. ;)