bandwidth

bandwidth

Compute bandwidth for GPU and CPU at different matrix sizes.

Usage

Bandwidth for float

Change these lines about type definations in bandwidth.c as below:

#define   ELEM_TYPE                     float
#define   ELEM_TYPE_STR                 "float"
#define   CL_ELEM_TYPE                  cl_float
#define   CL_ELEM_TYPE_STR              "float"

And then, build bandwidth.c using following command:

$ ./make.sh

If build's okay, you can execute ./bandwidth first to check how to use:

$ ./bandwidth 
>>> [USAGE] ./bandwidth HEGHTA WIDTHA KERNEL_FILE_PATH KERNEL_FUNC_NAME LOOP_EXECUTION_TIMES GLOBAL_WORK_SIZE[0] GLOBAL_WORK_SIZE[1] GLOBAL_WORK_SIZE[2]

============== INIT ==============
>>> [INFO] ELEM_TYPE_STR: float, sizeof(ELEM_TYPE): 4
>>> [INFO] CL_ELEM_TYPE_STR: float, sizeof(CL_ELEM_TYPE): 4
>>> [INFO] cl_program_build_options: -D CL_ELEM_TYPE=float -D CL_INPUT_TYPE=float
>>> [ERROR] please input args

Assuming a 2048*2048 matrix, preparing-execution kernel file is kernel.cl, preparing-execution function is global_bandwidth_vec1 (vec1 representing non-vectorization) and run 100 times to measure bandwidth, global work size is (2048*2048, 1, 1):

# >>> [USAGE] ./bandwidth HEGHTA WIDTHA KERNEL_FILE_PATH KERNEL_FUNC_NAME LOOP_EXECUTION_TIMES GLOBAL_WORK_SIZE[0] GLOBAL_WORK_SIZE[1] GLOBAL_WORK_SIZE[2]
$ ./bandwidth 2048 2048 ./kernel.cl global_bandwidth_vec1 100 $[2048*2048] 1 1

Bandwidth for float8

Change these lines in bandwidth.c first:

#define   ELEM_TYPE                     float
#define   ELEM_TYPE_STR                 "float"
#define   CL_ELEM_TYPE                  cl_float8
#define   CL_ELEM_TYPE_STR              "float8"

Build bandwidth.c:

$ ./make.sh

Execute binary file as below, and watch out the difference between float and float8:

# >>> [USAGE] ./bandwidth HEGHTA WIDTHA KERNEL_FILE_PATH KERNEL_FUNC_NAME LOOP_EXECUTION_TIMES GLOBAL_WORK_SIZE[0] GLOBAL_WORK_SIZE[1] GLOBAL_WORK_SIZE[2]
$ ./bandwidth 2048 2048 ./kernel.cl global_bandwidth_vec8 100 $[2048*2048/8] 1 1

Bandwidth for half

Change these lines in bandwidth.c:

#define   ELEM_TYPE                     __fp16
#define   ELEM_TYPE_STR                 "__fp16"
#define   CL_ELEM_TYPE                  cl_half 
#define   CL_ELEM_TYPE_STR              "half"

Build:

$ ./make.sh

Execute:

$ # >>> [USAGE] ./bandwidth HEGHTA WIDTHA KERNEL_FILE_PATH KERNEL_FUNC_NAME LOOP_EXECUTION_TIMES GLOBAL_WORK_SIZE[0] GLOBAL_WORK_SIZE[1] GLOBAL_WORK_SIZE[2]
$ ./bandwidth 2048 2048 ./kernel.cl global_bandwidth_vec1 100 $[2048*2048] 1 1

Bandwidth for half16

Change these lines in bandwidth.c:

#define   ELEM_TYPE                     __fp16
#define   ELEM_TYPE_STR                 "__fp16"
#define   CL_ELEM_TYPE                  cl_half 
#define   CL_ELEM_TYPE_STR              "half16"

Note: The half type is an outlier on host (halfN is not defined in host: cl_half2, cl_half4, cl_half8 and cl_half16 are not in /usr/include/CL/cl.h), but okay on device (half, half2, half4, half8, half16). If define CL_ELEM_TYPE as cl_half16, it'll cause a problem: cl_halfN is undeclared.

Build:

$ ./make.sh

Execute:

$ # >>> [USAGE] ./bandwidth HEGHTA WIDTHA KERNEL_FILE_PATH KERNEL_FUNC_NAME LOOP_EXECUTION_TIMES GLOBAL_WORK_SIZE[0] GLOBAL_WORK_SIZE[1] GLOBAL_WORK_SIZE[2]
$ ./bandwidth 2048 2048 ./kernel.cl global_bandwidth_vec16 100 $[2048*2048/16] 1 1

Frequency Monitor & Modification

Please refer to tools directory.