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- 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 <your application name> 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
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