Hello all,
NERSC's edison cluster specifies -xHost in its cfg file. However login nodes and compute nodes are actually different (Sandy Bridge vs. Ivy Bridge cpus).
A quick test removing -xHost reveals a possible reason: without -xHost the compiled exectuables do not run on the head node. No for the actual question: is it worthwhile to claim cross compilation (and the requirement to have to specify endianess, type sizes etc manually) to possibly gain some more speed?
Given that Ivy and Sandy Bridge are tick and tock I would not expect much of a gain (though maybe Ivy Bridge actually offers wider AVX instructions?).
At least I will add a comment to edison.cfg explaining why either -xHost is used or why a cross compilation is required.
Yours, Roland