4 Replies Latest reply on Mar 28, 2012 5:29 PM by nervi

    ACML 5.1.0 or ACML 4.4.0?



      I'm compiling quantum chemical number-crunching applications on a linux machine with 4 x Opteron 6168, using gfortran 4.6.2.

      I'm wondering which ACML version is best for this family (10) of processors: acml 4.4.0 reports "optimized for amd fam 10", whereas 5.1.0 reports "optimized for amd fam 15". Since, as far as I undestood, some vectors instructions are available under family 15 (Bulldozer), but not under family 10 (Barcelona) I'm wondering whether 5.1.0 under opteron 6168 uses fast vectorized algebra or not...




        • Re: ACML 5.1.0 or ACML 4.4.0?

          You can use either version of the library.  ACML 5.1.0 was primarily released to provide support for our newest Family 15h processors, however it includes the same optimizations that 4.4.0 had for our Family 10h processors.


          Using the gfortran compiler as an example, if you are building for our newest Bulldozer processors you would use the libraries in gfortran64_fma4, while for the Opteron 6168 you would use the libraries in gfortran64.

            • Re: ACML 5.1.0 or ACML 4.4.0?

              Thanks for the answer. However I was wondering whether the library gfortran64 in ACML 5.1.0 contains or not the fast math vector. For example, in ACML 4.4.0 I was using explicitly gfortran64_mv to include math vect, and gfortran64 to don't use math vect. (i.e. CFLAGS         = -Ofast -march=native -ftree-vectorize -funsafe-math-optimizations -mveclibabi=acml and linking with gfortran64/lib/libacml_mv.a)


              How about ACML 5.1.0? May I use  CFLAGS         = -Ofast -march=native -ftree-vectorize -funsafe-math-optimizations -mveclibabi=acml and link against   gfortran64/lib/libacml.a (or gfortran64 lib or whathever is named)?


              As far as I  understood I cannot use gfortran64_fma4 of ACML 5.1.0 because I need family 15 CPUs...


              From your words I understood that for my needs it should be better to use ACML 4.4.0 (BTW I have a local copy, but the version for gfortran64 is disappeared from the download page).


              [Added]: Can you confirm that if I want to use mv library I have to switch to ACML 4.4.0 on fam 10h CPUs?


              Thanks again,