Hello Erik, > It's strange that code without "-xHost" does not run on the head node. What > other compiler options are there? The only reason I can see is that the > Intel compiler has been installed in a special way to use additional > compiler flags, and these flags make the code not work any more on Sandy > Bridge. It is some runtime detection that fails. I get: --8<-- Please verify that both the operating system and the processor support Intel(R) F16C instructions. --8<-- and adding -xHost complains that "icc: command line warning #10121: overriding '-xCORE-AVX-I' with '-xHost'" so it seesm as if some vectorization is enabled by the cray cc wrapper.
> To my knowledge, the processors accept the same machine instructions. The > CPU tuning might be different. Is this also true for vectorization? Or maybe this really is just a lack of OS support for the AVX registers on the login nodes. -xAVX seems to work fine and the only difference (according to the man page for icpc) are "Float-16 conversion instructions and the RDRND instruction". Float16 conversion would fit the F16C acronym in the error message. > Running short tests or compiled utilities on the head nodes is very > convenient. I would continue to make sure the code runs everywhere until > there is a proven performance benefit. Yes, that is what I would do as well. Yours, Roland -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://keys.gnupg.net.
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