opencl - Is there a good way to choose the right platform on the fly? -

because computer using has amd, nvidea, , intel platforms. how can know right platform use on users computer? have loop tries create platform, device, context, , queue every platform. if fails @ point tries next platform.

    readkernel();      numplatforms = getnumplatforms(); test     platforms = getplatforms(); test     for(int = 0; < numplatforms; i++)     {         numdevices = getnumdevices(platforms[i]); test_and_continue         devices = getdevices(platforms[i], numdevices); test_and_continue         context = createcontext(platforms[i], devices); test_and_continue         queue = getcommandqueue(context, devices[0]); test_and_continue          // setup. can post info here ->  getdeviceinfo(devices[0]);         break;      }     program = createprogram(context, source); test     buildprogram(program); test     kernel = buildkernel(program, appname); test 

is way or there better way?

as usual kind of question, answer is: depends on need. or in other words, need define "the right platform".

here cases can think of (i'm sure can find others):

• you developed kernel using features specific version of ocl. using clgetplatforminfo, query each platform present find 1 has proper ocl version.

• you optimized kernel specific type of device (cpu, gpu). filter devices interested in using appropriate flag (cl_device_type_typename) clgetdeviceids.

• you want parallelized as possible computation, have move lot of data device. in case might have found out running kernel on igpu gives best performance. function clgetdeviceinfo , flag cl_device_host_unified_memory can determine if have such device available.

• with clgetdeviceinfo function can query specific vendor extension want use (flag: cl_device_extensions). note clgetplatforminfo provides list of extension supported platform.

• you have several gpus available , want 1 "best performance". still clgetdeviceinfo can query specifications of device. based on these specs can make choice. instance can found out if device has cache (cl_device_global_mem_cache_type) , if yes how (cl_device_global_mem_cacheline_size). can query clock frequency (cl_device_max_clock_frequency) or how many compute units available on device (cl_device_max_compute_units).