I'm using the Intel OpenCL driver on a Debian 7 64-bit, dual E5-2670 machine, programming with the PyOpenCL interface to OpenCL.
When I query available devices on the Intel platform, I see one device named 'Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz'. Using this single OpenCL device, with a large work group size, I see that only one physical CPU is being used.
When I start a second program using the same device, I see that they compete for CPU time instead of being distributed, one on each CPU.
Is this a known limitation of the Intel OpenCL driver, or is there a workaround to use both CPUs?