This is a collection of simple streaming kernels for teaching purposes. It is heavily inspired by John McCalpin's https://www.cs.virginia.edu/stream/.

It contains the following streaming kernels with corresponding data access pattern (Notation: S - store, L - load, WA - write allocate):

init (S1, WA): Initilize an array. Store only.
sum (L1): Vector reduction. Load only.
copy (L1, S1, WA): Classic memcopy.
update (L1, S1): Update a vector. Also load + store but without write allocate.
triad (L2, S1, WA): Stream triad - a = b + b * scalar.
daxpy (L2, S1): Daxpy - a = a + b * scalar.
striad (L3, S1, WA): Schoenauer triad - a = b + c * d.
sdaxpy (L3, S1): Schoenauer triad without write allocate - a = a + b * c.

Build

Configure the toolchain to use in the Makefile:

TAG = GCC  # Supported GCC, CLANG, ICC

Review the flags for toolchain in the corresponding included file, e.g. include_GCC.mk. OpenMP is disabled per default, you can enable it by uncommenting the OpenMP flag:

OPENMP   = -fopenmp

Build with:

make

You can build multiple toolchains in the same directory, but notice that the Makefile is only acting on the one currently set. Intermediate build results are located in the <TOOLCHAIN> directory.

To output the executed commands use:

make Q=

Clean up with:

make clean

to clean intermediate build results.

make distclean

to clean intermediate build results and binary.

(Optional) Generate assembler:

make asm

The assembler files will also be located in the <TOOLCHAIN> directory.

Usage

To run the benchmark call:

./bwBench-<TOOLCHAIN>

The benchmark will output the results similar to the stream benchmark. Results are validated. For threaded execution it is recommended to control thread affinity.

We recommend to use likwid-pin for benchmarking:

likwid-pin -c 0-3 ./bwbench-GCC

Example output for threaded execution:

-------------------------------------------------------------
[pthread wrapper] 
[pthread wrapper] MAIN -> 0
[pthread wrapper] PIN_MASK: 0->1  1->2  2->3  
[pthread wrapper] SKIP MASK: 0x0
        threadid 140271463495424 -> core 1 - OK
        threadid 140271455102720 -> core 2 - OK
        threadid 140271446710016 -> core 3 - OK
OpenMP enabled, running with 4 threads
-------------------------------------------------------------
Function      Rate (MB/s)   Avg time     Min time     Max time
Init:        14681.5000       0.0110       0.0109       0.0111
Sum:         20634.9290       0.0079       0.0078       0.0082
Copy:        18822.2827       0.0172       0.0170       0.0176
Update:      28135.9717       0.0115       0.0114       0.0117
Triad:       19263.0634       0.0253       0.0249       0.0268
Daxpy:       26718.1377       0.0182       0.0180       0.0187
STriad:      21229.4470       0.0305       0.0301       0.0313
SDaxpy:      26714.3897       0.0243       0.0240       0.0253
-------------------------------------------------------------
Solution Validates