Re: SGX Performance Creep

["Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>]

On Mon, 2021-03-08 at 16:40 -0800, Dave Hansen wrote:
> I got my hands on a NUC7CJYH, which is the first piece of functional
> Flexible Launch Control hardware I've actually laid my hands on.
> 
> I went looking for any "performance creep".  I tried a very simple test:
> Create and run an enclave that touches a 64MB statically-allocated
> buffer.  (The patch to the kernel selftest to do this is attached).
> 
> tl;dr: I'm not seeing any meaningful change in runtimes, even after
> running and tearing down the enclave for 6-7 hours.
> 
> I'm running the selftest like this, creating a log file with /usr/bin/time:
> 
> NOW=$(date +%s); make && while true; do /usr/bin/time ./test_sgx >>
> $NOW.log 2>> $NOW.timelog || break; done
> 
> This lets me do a quick and dirty histogram of the runtimes.  Note that
> there's a single, nice peak.  It's not "smeared" like I would expect
> from slowly-degrading run times.
> 
> $ cat 1615229976.timelog  | grep elapsed | awk '{print $1}' | sort | uniq -c
>       4 2.08user
>      14 2.09user
>     106 2.10user
>     403 2.11user
>    1055 2.12user
>    1518 2.13user
>    1268 2.14user
>     726 2.15user
>     302 2.16user
>      96 2.17user
>      23 2.18user
>       8 2.19user
>       1 2.20user

I think it would be a great enhancement for the self-test, if you could

1. Make the test program change attached.
2. Create a script for stress test and histogram.


> 
> I'll run for another day or two and see if anything interesting shows
> up.  But, for now, nothing interesting is happening.  Whatever folks are
> seeing, it doesn't seem to be present on my little simple test case, or
> this Atom-based hardware.
> 
> The kernel is: stock 5.12.0-rc2.
> The CPU is: Intel(R) Celeron(R) J4005 CPU @ 2.00GHz
> 

/Jarkko