Affects Version/s: None
Fix Version/s: None
Environment:Argonne's Theta machine is a Cray running lustre: 184.108.40.206
I'm going to bug Cray about this but Andreas said "we can't fix problems that aren't in Jira" so here I am.
In the old days one would get striping information via an ioctl:
Then the llapi_ routines showed up:
and even more sophisticated llapi_layout_ routines:
I haven't done a full scaling run, but small scale tests don't look great for the newer interfaces. Average time to get the stripe size for a 2 node 128 process MPI job:
ioctl: 17.2 ms
llapi_file_get_stripe: 142.0 ms
llapi_layout: 2220 ms
Wow! I want to use the new interfaces but these overheads are bonkers.