Intel Xeon Phi and High Bandwidth Memory
High Bandwith Memory
High Bandwidth Memory (HBM) is a high bandwidth RAM interface for 3D-stacked DRAM developed by AMD. Hybrid Memory Cube Interface developed by Micron Technology is also a similar technology but is not compatible with HBM. HBM has been designed to provide higher bandwidth than DDR4 (for CPUs) and GDDR5 (for GPUs) while demanding less power and space. Furthermore, it is compatible with on-chip integration, while other technologies (DRAM, NAND) are not, which allows for even higher performance benefit.
Technology
HBM consists of a number of stacked DRAM dies, with each one having a set of independent channels available to for access by the processors. Each channel interface maintains a 128-bit data bus operating at DDR data rates. The DRAM dies connect to the CPU or GPU through an ultra-fast interconnect called the “interposer. Several stacks of HBM are plugged into the interposer alongside a CPU or GPU, and that assembled module connects to a circuit board. Though these HBM stacks are not physically integrated with the CPU or GPU, they are so closely and quickly connected via the interposer that HBM’s characteristics are nearly indistinguishable from on-chip integrated RAM
