Global memory with OpenCL

Prasanna_P_ · ‎07-23-2013

Hi,

The Intel Xeon Phi we have has 7936MB of GDDR memory according to micinfo. However when I query the available global memory in OpenCL using clGetDeviceInfo, it says that the size is only 1677MB. Why is this so? Is there any environment variable or setting I need to change to fix this?

Thanks,

Prasanna.

Sumedh_N_Intel · ‎07-24-2013

The OpenCL runtime competes with other offload and native applications for memory. Also, since the coprocessor uses a RAM FS, the amount of memory available at execution is smaller than what is reported by micinfo. These are two primary reason why your application may be reporting lower global memory values. With that said, 1677MB doesn't seem quite right. If possible, could you reboot the coprocessor and try running this test so that you have maximum memory available to your application.

Prasanna_P_ · ‎07-25-2013

Hi Sumedh,

Thank you for the reply. I tried rebooting the coprocessor using micctrl -r and micctrl -b and it still shows available global memory as 1677MB. The device is running an older flash version (2.1.01.0372). Could this be a reason? I am awaiting response on one of my other threads regarding this issue before I do a flash update: http://software.intel.com/en-us/comment/1744331

Thanks,

Prasanna.

Sumedh_N_Intel · ‎07-25-2013

I am not sure if this could be a result of an older flash version. Could you send me the output of micinfo and a small reproducer? Also, what version of OpenCL SDK and runtime are you using?

Prasanna_P_ · ‎07-28-2013

The memory issue is resolved. It was a rather stupid mistake in my code. The available memory shown is 5773MB. The OpenCL version I am using is 3.0.67279-2. However the MPSS version I am running is 2.1.5889-17. Do I need to install the older SDK version to work with this version of MPSS?

Thanks,

Prasanna.

Loc_N_Intel · ‎07-29-2013

For the latest Intel(R) SDK for OpenCL* Applications XE 2013 (version 3.0.67279), you must to install Intel(R) MPSS Update 3 or higher (mpss_gold_update_3.2.1.6720-15). We don't recommand you downgrade the MPSS.

Thanks.