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96 lines
2.5 KiB
ReStructuredText
96 lines
2.5 KiB
ReStructuredText
.. Copyright 2003-2024 by Wilson Snyder.
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.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
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verilator_gantt
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===============
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Verilator_gantt creates a visual representation to help analyze Verilator
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multithreaded simulation performance by showing when each macro-task
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starts, ends, and when each thread is busy or idle.
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For an overview of the use of verilator_gantt, see :ref:`Profiling`.
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Gantt Chart VCD
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---------------
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Verilated_gantt creates a value change dump (VCD) format dump file which
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may be viewed in a waveform viewer (e.g., C<GTKWave>):
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.. figure:: figures/fig_gantt_min.png
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Example verilator_gantt output, as viewed with GTKWave.
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The viewed waveform chart has time on the X-axis, with one unit for each
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time tick of the system's high-performance counter.
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Gantt Chart VCD Signals
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-----------------------
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In waveforms, there are the following signals. In GTKWave, use "decimal"
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data format to remove the leading zeros and make the traces easier to read.
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trace/section
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Shows the name of the current top of the execution section stack.
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Set GTKWave data format to "ASCII".
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trace/depth
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Shows the depth of the execution section stack.
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Set GTKWave data format to "Analog".
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measured_parallelism
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The number of mtasks active at this time, for best performance, this will
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match the thread count. In GTKWave, use a data format of "analog step" to
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view this signal.
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predicted_parallelism
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The number of mtasks Verilator predicted would be active at this time,
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for best performance this will match the thread count. In GTKWave, use a
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data format of "analog step" to view this signal.
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cpu#_thread
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For the given CPU number, the thread number measured to be executing.
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mtask#_cpu
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For the given mtask id, the CPU it was measured to execute on.
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thread#_mtask
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For the given thread number, the mtask id it was executing.
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predicted_thread#_mtask
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For the given thread number, the mtask id Verilator predicted would be
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executing.
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verilator_gantt Example Usage
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-----------------------------
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..
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verilator_gantt --help
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verilator_gantt --version
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verilator_gantt profile_exec.dat
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verilator_gantt Arguments
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-------------------------
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.. program:: verilator_gantt
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.. option:: <filename>
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The filename to read data from; the default is "profile_exec.dat".
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.. option:: --help
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Displays a help summary, the program version, and exits.
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.. option:: --no-vcd
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Disables creating a .vcd file.
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.. option:: --vcd <filename>
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Sets the output filename for vcd dump; the default is "verilator_gantt.vcd".
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