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AR# 55904

2013.1 Vivado - The percentage of memory in the utilization report is understated

Description

In the utilization report (after opening synthesized/implemented design), you can see the memory usage:

Memory(16 of 405; 4%)
RAMB36/FIFO36 (16 of 135; 12%)
RAMB18/FIFO18 (0 of 270 ; 0% )

In the above example, the percentage of RAMB36/FIFO36(12%) and RAMB18/FIFO18(0%) is correct, but the percentage for the total memory should be 12% (not 4%) because RAMB36/FIFO36 and RAMB18/FIFO18 share the same memory resource.

Solution

The calculation of the block RAM utilization report has been updated in Vivado Design Suite 2013.2.

Memory(16 of 135; 12%)
     -Block RAM Tile(16 of 135; 12%)
        -- RAMB36/FIFO36 (16 of 135; 12%)
        -- RAMB18/FIFO18 (0 of 270 ; 0% )

Where Vivado calculates the Block RAM Tile as follows:

Block RAM Tile = (RAMB36 + FIFO36E1) + (FIFO18E1 + RAMB18E1) / 2
AR# 55904
Date Created 05/07/2013
Last Updated 12/17/2013
Status Active
Type Known Issues
Tools
  • Vivado Design Suite - 2013.1