srun command at NERSC requires node type option

[BrianS]

srun: error: No hardware architecture specified (-C)!

in docs/build_devel.md we have the line

export CROSS=cray-aries-slurm
srun -n 10 $(nobs exe test/hello_upcxx.cpp)

and we should be telling them

on Cori for a Haswell execution

export CROSS=cray-aries-slurm
srun -C haswell -n 10 $(nobs exe test/hello_upcxx.cpp)

for KNL

export CROSS=cray-aries-slurm
srun -C knl -n 10 $(nobs exe test/hello_upcxx.cpp)

[Dan Bonachea]

srun from the front end automatically submits an interactive job, but this is a very slow mode of operation that should normally not be used (because it can easily add 10+ minutes of queue time to the start of each command).

The "right" way to operate is create an interactive job with a command like:

salloc -n 10 -N 1 --qos=interactive -t1:00:00 -L SCRATCH -C knl

and then from the interactive job prompt srun commands (including those issued by upcxx-run) will operate as expected.

This is also important when doing performance measurements with more than one node, to ensure you are using the same set of nodes for all runs being compared.

[BrianS]

We should likely update the docs to state this. It's where I ended up, but the docs are a handy way to bring team members up to speed.