Visible to Intel only — GUID: GUID-A860491F-3E9E-4DCF-8789-24267007704E
Visible to Intel only — GUID: GUID-A860491F-3E9E-4DCF-8789-24267007704E
Partitioning Buffers Across Memory Channels of the Same Memory Type
By default, the Intel® oneAPI DPC++/C++ Compiler configures each global memory type in a burst-interleaved manner. Usually, the burst-interleaving configuration leads to the best load balancing between the memory channels. However, there might be situations where it is more efficient to partition the memory into non-interleaved regions. For additional information, refer to Global Memory Accesses Optimization.
The Global Memory Partitions diagram in Global Memory Accesses Optimization illustrates the differences between burst-interleaved and non-interleaved memory partitions.
To manually partition some or all of the available global memory types, perform the following tasks:
- Create a buffer with property::buffer::mem_channel specifying channel ID in its property_list.
- Specify property::buffer::mem_channel with value 1 to allocate the buffer in the lowest available memory channel (default).
- Specify property::buffer::mem_channel with value 2 or greater to allocate the buffer in the higher available memory channel.
Here is an example buffer definition:
range<1> num_of_items{N}; buffer<T, 1> bufferA(VA.data(), num_of_items, {property::buffer::mem_channel{1}}); buffer<T, 1> bufferB(VB.data(), num_of_items, {property::buffer::mem_channel{2}}); buffer<T, 1> bufferC(VC.data(), num_of_items, {property::buffer::mem_channel{3}});
- Compile your design kernel using the =<global_memory_name>> flag to configure the memory channels of the specified memory type as separate addresses. For more information about the use of the =<global_memory_name> flag, refer to the Disable Burst-Interleaving of Global Memory (-Xsno-interleaving) section.
IMPORTANT:If you do not specify the -Xsno-interleaving option in your compiler command and have specified the mem_channel property on buffers in your kernel, the compiler assumes that a =default option was specified in the compiler command. This behavior might change in a future release, so ensure that you always explicitly set the =<global_memory_name>> option in the compiler command when using the mem_channel property.
- Do not set more than one memory channel property on a buffer.
- If the memory channel specified is not available on the target board, the buffer is placed in the first memory channel.