GotoBLAS2 FAQ 1. General 1.1 Q Can I find useful paper about GotoBLAS2? A You may check following URL. http://www.cs.utexas.edu/users/flame/Publications/index.htm 11. Kazushige Goto and Robert A. van de Geijn, " Anatomy of High-Performance Matrix Multiplication," ACM Transactions on Mathematical Software, accepted. 15. Kazushige Goto and Robert van de Geijn, "High-Performance Implementation of the Level-3 BLAS." ACM Transactions on Mathematical Software, submitted. 1.2 Q Does GotoBLAS2 work with Hyperthread (SMT)? A Yes, it will work. GotoBLAS2 detects Hyperthread and avoid scheduling on the same core. 1.3 Q When I type "make", following error occured. What's wrong? $shell> make "./Makefile.rule", line 58: Missing dependency operator "./Makefile.rule", line 61: Need an operator ... A This error occurs because you didn't use GNU make. Some binary packages install GNU make as "gmake" and it's worth to try. 1.4 Q Function "xxx" is slow. Why? A Generally GotoBLAS2 has many well optimized functions, but it's far and far from perfect. Especially Level 1/2 function performance depends on how you call BLAS. You should understand what happends between your function and GotoBLAS2 by using profile enabled version or hardware performance counter. Again, please don't regard GotoBLAS2 as a black box. 1.5 Q I have a commercial C compiler and want to compile GotoBLAS2 with it. Is it possible? A All function that affects performance is written in assembler and C code is just used for wrapper of assembler functions or complicated functions. Also I use many inline assembler functions, unfortunately most of commercial compiler can't handle inline assembler. Therefore you should use gcc. 1.6 Q I use OpenMP compiler. How can I use GotoBLAS2 with it? A Please understand that OpenMP is a compromised method to use thread. If you want to use OpenMP based code with GotoBLAS2, you should enable "USE_OPENMP=1" in Makefile.rule. 1.7 Q Could you tell me how to use profiled library? A You need to build and link your application with -pg option. After executing your application, "gmon.out" is generated in your current directory. $shell> gprof gmon.out Each sample counts as 0.01 seconds. % cumulative self self total time seconds seconds calls Ks/call Ks/call name 89.86 975.02 975.02 79317 0.00 0.00 .dgemm_kernel 4.19 1020.47 45.45 40 0.00 0.00 .dlaswp00N 2.28 1045.16 24.69 2539 0.00 0.00 .dtrsm_kernel_LT 1.19 1058.03 12.87 79317 0.00 0.00 .dgemm_otcopy 1.05 1069.40 11.37 4999 0.00 0.00 .dgemm_oncopy .... I think profiled BLAS library is really useful for your research. Please find bottleneck of your application and improve it. 1.8 Q Is number of thread limited? A Basically, there is no limitation about number of threads. You can specify number of threads as many as you want, but larger number of threads will consume extra resource. I recommend you to specify minimum number of threads. 2. Architecture Specific issue or Implementation 2.1 Q GotoBLAS2 seems to support any combination with OS and architecture. Is it possible? A Combination is limited by current OS and architecture. For examble, the combination OSX with SPARC is impossible. But it will be possible with slight modification if these combination appears in front of us. 2.2 Q I have POWER architecture systems. Do I need extra work? A Although POWER architecture defined special instruction like CPUID to detect correct architecture, it's privileged and can't be accessed by user process. So you have to set the architecture that you have manually in getarch.c. 2.3 Q I can't create DLL on Cygwin (Error 53). What's wrong? A You have to make sure if lib.exe and mspdb80.dll are in Microsoft Studio PATH. The easiest way is to use 'which' command. $shell> which lib.exe /cygdrive/c/Program Files/Microsoft Visual Studio/VC98/bin/lib.exe