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- default 1 second, each direction, before measurements

- default to 100

- may need some tweaks to confirm/correct which interface is used

- match current style on cooley and bebop
- set explicit HOME to avoid interference from user spack env

- must build benchmarks twice, once with pmdk back end and once with
  file backend
- rpath in executable keeps a fixed library linkage otherwise

- includes two bake builds: one with pmdk, one with file backend
- actual runs do not work yet due to a mount problem

- size of buffer to iterate over during transfer
- if this size matches transfer size, then a single hot buffer will be used
  repeatedly for all operations

- some examples are crashing at runtime, not sure why yet

- set $HOME to avoid perturbing ~/ config files for the user running this script
- remove deprecated --dirty and LD_PRELOAD hacks
- remove explicit set of SPACK_ROOT in favor of variable set by spack itself
- other misc streamlining improvements