03_shared-memory/00_stream

Hands-on: Building STREAM benchmark

0. Legend

• [src_dir] : source directory
• [rist_dir]: this directory

1. Get source file

$ bash 00_dl.sh
$ ls
stream.v5  # The directory name is specified in 00_dl.sh. In this case, [src_dir] is stream.v5.

2. Preparation

$ cd [src_dir]
$ cp [rist_dir]/rist/Makefile.fj .
$ cp [rist_dir]/rist/Makefile.fj_zfill .

• We recommend that you modify the source code to properly show the results. See [rist_dir]/rist/patch.rist. We show a way of applying the patch file here.

$ patch -p 1 -d [src_dir] < [rist_dir]/rist/patch.rist
patching file stream.c
patching file stream.f

3. Set array size

• STREAM is a benchmark to measure memory bandwidth (memory access throughput, bytes/sec).
• Therefore, the memory size for the arrays needs to be larger than the size of the Last-level cache (LLC) in your machine.
• Set the array size in the following manner. Recall that the LLC of A64FX is L2 and its size is 4x8(=32)MiB.
  • As for FORTRAN (stream.f): Edit PARAMETER n in stream.f.
  • As for C (stream.c): Edit STREAM_ARRAY_SIZE in stream.c. Or, set -DSTREAM_ARRAY_SIZE in makefile.

4. Compile

• You can find the executable file in each of Obj_*** directories.
• If you want to use own compiler, use Makefile.fj_zill.own and so on.
  • If you set a quite large array size, compiling would be failed. In this case, add -mcmodel=large to the compiler option.
• Compare the compiler options (CFLAGS and FFLAGS) of Makefile.fj to those of Makefile.fj_zfill.

$ cd [src_dir]
# We show the case when one choose Makefile.fj_zfill, for example:
$ make -f Makefile.fj_zfill &> make.fj_zfill.log
$ ls 
Obj_c.fj_zfill  Obj_ctrad.fj_zfill  Obj_f.fj_zfill  

Note

• We summarize the main compiler options of each Makefile.

Makefile.fj            #Optimization level is fast. Auto-vectorization is allowed. OpenMP thread is allowed. 
Makefile.fj_zfill      #Optimization level is fast. Auto-vectorization is allowed. OpenMP thread is allowed. ZFILL option is set.