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AR# 16411

5.1i HDL Bencher - Small changes to a testbench waveform (TBW) cause HDL Bencher to use a large amount of memory and appear to hang

Description

Keywords: lock, toggle, input, respond, memory, usage, allocation, not responding, .tbw, freeze

Urgency: Standard

General Description:
Small changes to a testbench waveform cause HDL Bencher to use a large amount of memory and appear to hang. I can open a testbench without a problem, but a small change (such as toggling a signal or moving the end of testbench marker) causes HDL Bencher to freeze for a time. When I check the process information, I notice that HDL Bencher is using a large amount of memory.

Solution

HDL Bencher dynamically adds additional clock cycles to the end of a testbench as you near the end of a waveform. However, as with longer waveforms and waveforms with larger numbers of signals, this dynamic allocation and other similar events cause HDL Bencher to react slowly or appear to hang because of the memory requirements of handling (the number of signals) x (the number of possible transition points).

In reviewing the code, Xilinx found that HDL Bencher's memory usage is not as efficient as it could be. In the 6.1i release, the code has been enhanced to use as much as 80%-90% less memory.
AR# 16411
Date Created 12/18/2002
Last Updated 02/07/2006
Status Archive
Type General Article