# of OpenCL devices on 2012 Macbook pro - macos

Question

I'm writing an openCL program on a mid 2012 13" macbook pro with the following specs:
Processor: 2.9 GHz Intel Core i7
Graphics: Intel HD Graphics 4000
In my program I do the following to check how many devices I have access to:
// get first platform
cl_platform_id platform;
err = clGetPlatformIDs(1, &platform, NULL);
// get device count
cl_uint gpuCount;
err = clGetDeviceIDs(platform, CL_DEVICE_TYPE_GPU, 0, NULL, &gpuCount);
cl_uint cpuCount;
err |= clGetDeviceIDs(platform, CL_DEVICE_TYPE_CPU, 0, NULL, &cpuCount);
std::cout<<"NUM CPUS: "<<cpuCount<<" NUM GPUS: "<<gpuCount<<std::endl;
After execution, my program states that I have only one CPU and zero GPUs.
How can that be? Is openCL not compatible with Intel HD Graphics 4000 card? And I thought my computer had a dual core processor. So shouldn't there be 2 CPUs and 1 GPU?
Or am I simply not fetching the data correctly?
EDIT: I have found the issue. After upgrading my OS to Mavericks (was previously running Mountain Lion), openCL now recognizes my graphics card as a valid device.

Answer 1

Your processor has multiple cores, which are recognized as Compute Units. Run following code snippet & check that number of CU is as expected:
cl_device_id device;
cl_uint max_compute_units;
cl_int ret = clGetDeviceInfo(device, CL_DEVICE_MAX_COMPUTE_UNITS, sizeof(cl_uint), &max_compute_units, NULL);
printf("Number of computing units: %u\n", max_compute_units);

Answer 2

This doesn't answer your question, (and doesn't need downvoting please) but hopefully will help you work out what you have actually got installed. I would have posted it as a comment, but the formatting there would be useless.
If you want a legible list of your installed CPU and Graphics equipment, the following command does it nicely:
system_profiler | awk '/^Hardware/ || /^Graphics/{p=1;print;next} /^[A-Za-z]/{p=0} p'
Graphics/Displays:
AMD Radeon HD 6970M:
Chipset Model: AMD Radeon HD 6970M
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 1024 MB
Vendor: ATI (0x1002)
Device ID: 0x6720
Revision ID: 0x0000
ROM Revision: 113-C2960H-203
EFI Driver Version: 01.00.560
Displays:
iMac:
Display Type: LCD
Resolution: 2560 x 1440
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Built-In: Yes
Hardware:
Hardware Overview:
Model Name: iMac
Model Identifier: iMac12,2
Processor Name: Intel Core i7
Processor Speed: 3.4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Memory: 16 GB
Boot ROM Version: IM121.0047.B1F
SMC Version (system): 1.72f2
Serial Number (system): DGKH90PWDHJW
Hardware UUID: 1025AC04-9F8E-5342-9EF4-XXXXXXXXXXXXX
And also this for the actual CPU details:
sysctl -a | grep "brand_string"
machdep.cpu.brand_string: Intel(R) Core(TM) i7-2600 CPU # 3.40GHz
And this for OpenCL version:
system_profiler | grep -A 11 OpenCL:
OpenCL:
Version: 2.3.59
Obtained from: Apple
Last Modified: 19/09/2014 10:28
Kind: Intel
64-Bit (Intel): Yes
Signed by: Software Signing, Apple Code Signing Certification Authority, Apple Root CA
Get Info String: 2.3.59, Copyright 2008-2013 Apple Inc.
Location: /System/Library/Frameworks/OpenCL.framework
Private: No
P.S. If there is a better way to provide additonal, useful information (which is not really a proper answer) on SO than this, please let me know.