AN 1003: Multi Memory IP System Resource Planning: for Intel Agilex® 7 M-Series FPGAs

ID 788295
Date 11/22/2023
Public
Document Table of Contents

3.1.1. HBM2E UIB Controller Efficiency

For each HBM2E DRAM in an Intel Agilex® 7 M-Series FPGA, there are eight channels of 128-bits each, or 16 pseudo channels of 64-bits each.

The following equation calculates the ideal bandwidth that a memory can achieve, based on 100% controller efficiency:



For example, for a -1 speed grade device with a HBM2E interface running at 1.6 GHz, the ideal bandwidth per pseudo channel is:

(64 DQ × 1.6 GHz x 2)/8 = 25.6 GBps

Likewise, at -2 and -3 device speed grade, a single pseudo channel provides 22.4 GBps and 16 GBps, respectively.

HBM2E Controller Efficiency Preliminary Data shows the HBM2E controller efficiency specifications for various speed grades when using pseudo BL8 transfers. HBM2E Controller Efficiency Preliminary Data shows that sequential memory access demonstrates a higher typical efficiency compared to random memory access.

Table 2.  HBM2E Controller Efficiency Preliminary Data for -3 Device Speed Grade (2.0 GT/s), -2 Device Speed Grade (2.8 GT/s) and -1 Device Speed Grade (3.2 GT/s)
Access Pattern Read (%) Write (%) Controller Efficiency Specification (%)
2.0 GT/s 2.8 GT/s 3.2 GT/s
Sequential 50 50 > 80 > 70 > 65
Sequential 100 0 > 90 > 90 > 90
Sequential 0 100 > 90 > 90 > 90
Random 50 50 > 65 > 55 > 50
Random 100 0 > 65 > 55 > 50
Random 0 100 > 65 > 55 > 50
Note: HBM2E Controller Efficiency Preliminary Data reflects the specifications that the controller is designed to meet, and not actual measured efficiency data.

The per pseudo channel bandwidth of HBM2E for an FPGA depends on the following factors:

  • Data rate per bit
  • Data bus width
  • Data bus efficiency (percentage of time data is actively being transferred)

The following equation expresses the total effective bandwidth per interface as a function of all these factors:



If the HBM2E controller operates at 90% efficiency, the effective bandwidth is 23.04 GBps (25.6 GBps x 0.9) per pseudo channel, running at 1.6 GHz -1 speed grade. A single HBM2E, with 16 pseudo channels running at 1.6GHz, provides a total of 409.6GBps bandwidth.

You must account for HBM2E controller efficiency across various traffic scenarios that a memory can achieve (or that a memory can service) while determining overall system performance through the hard memory NoC.