Configuring HBM for report_power - 2020.2 English

Vivado Design Suite User Guide: Power Analysis and Optimization (UG907)

Document ID
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2020.2 English

The HBM is configured using the HBM IP wizard within an IP integrator block design or the IP catalog. Set the cell properties on HBM instance to access further HBM settings for report_power. Cell properties can be used to fine-tune power analysis. The following types of cells are available in an HBM instance:

  • HBM_ONE_STACK_INTF: if targeting a single HBM stack
  • HBM_TWO_STACK_INTF: if targeting two HBM stacks
Use the get_cells command to locate the HBM instance.
set hbm_inst [get_cells -hier -filter {REF_NAME == HBM_TWO_STACK_INTF}]

You can also locate HBM instance using Find in the Vivado® Integrated Design Environment as shown in the following figure:

Figure 1. HBM Instance Using Find in Vivado

The property values can be modified before running report_power. The following properties are used for power analysis:

  • PAGEHIT_PERCENT_00, PAGEHIT_PERCENT_01: The percentage of cycles that an HBM transaction accesses an open page, which results in the fastest access. For example, sequential memory accesses are more likely to occur within an open page which reduces power and increases efficiency.
  • READ_PERCENT_00 to READ_PERCENT_15 (Stack 0), READ_PERCENT_16 to READ_PERCENT_31 (Stack 1): The percentage of cycles that a pseudo-channel is reading from the HBM.
  • WRITE_PERCENT_00 to WRITE_PERCENT_15 (Stack 0), WRITE_PERCENT_16 to WRITE_PERCENT_31 (Stack 1): The percentage of cycles that a pseudo-channel is writing to the HBM.

Ensure reasonable values for READ_PERCENT and WRITE_PERCENT based on PAGEHIT_PERCENT. Use the following guidelines:

  • PAGEHIT_PERCENT < 75%: READ_PERCENT + WRITE_PERCENT should be 50% or less
  • PAGEHIT_PERCENT >= 75%: READ_PERCENT + WRITE_PERCENT should be 90% or less
Note: In the current release, PAGEHIT_PERCENT_00 and PAGEHIT_PERCENT_01 have a default value of 50. The default value will be corrected to 75 in a future release.

The following properties are assigned by HBM IP configuration and are not modified.

  • DATARATE_00 to DATARATE_15: Data rate for each memory controller in Gbps. Properties 00 to 07 apply to Stack 0 and 08 to 15 apply to Stack 1.
  • SWITCH_ENABLE_00, SWITCH_ENABLE_01: Reflects whether the dedicated AXI switch is enabled or disabled for a stack.

The following figure is an example of Report Power output for HBM, showing the breakdown of power between the device and HBM stacks.

Figure 2. Report Power for HBM