topic I believe that's not possible in OpenCL* for CPU

Disable TBB on CPU fallback

Alexander_Herz — Mon, 02 Sep 2013 14:49:37 GMT

Hi,

I have a slightly obscure problem :) For testing purposes we're running opencl inside a linux VM, so the actual gfx hardware is not accessable. We're using the CPU fallback from intel's opencl impl instead. Apparently, this impl is using TBB to get better performance but our environment does not allow for third parties to create any threads. We don't need any performance, just that it works at all. Is there a way (maybe by setting an environment variable) to disable the multi-threading inside intel's CPU based opencl driver?

Thx, Alex

I believe that's not possible

Raghupathi_M_Intel — Tue, 03 Sep 2013 17:40:30 GMT

I believe that's not possible. You may be able to play with global and local sizes to restrict the number of threads but the runtime still depends on tbb. I will fwd your question to see if there are workarounds.

Raghu

Ok. Looks like there is no

Raghupathi_M_Intel — Wed, 04 Sep 2013 16:58:08 GMT

Ok. Looks like there is no way to disable TBB.

Hi Alexander,

Yuri_K_Intel — Fri, 06 Sep 2013 12:25:58 GMT

Hi Alexander, Is it possible to adjust VM settings so it uses only 1 core (without HT)? Probably this will prevent TBB from creating new threads. Thanks, Yuri

Hi,

Maxim_S_Intel — Fri, 06 Sep 2013 12:31:32 GMT

Hi,

Also please look at Immediate Execution: http://software.intel.com/sites/products/documentation/ioclsdk/2013/UG/Intel_Immediate_Command_Execution_Extension.htm

Great, immidate exec seems to

Alexander_Herz — Fri, 06 Sep 2013 15:19:45 GMT

Great, immidate exec seems to fix my problem.

I assume the standard TBB ENV vars also work here?

Regards,

Alex

Thanks Max. I wasn't aware of

Raghupathi_M_Intel — Fri, 06 Sep 2013 17:55:09 GMT

Thanks Max. I wasn't aware of the extension. Moreover I misunderstood the question as "completely disabling tbb".