perfanno-vscode

Perfanno-vscode is a simple extension that allows users to annotate buffers using perf output information. The result is a beatiful heatmap showing developers where performance bottlenecks are slowing down their program.

Notes

• Most of the processing algorithm is taken directly from https://github.com/t-troebst/perfanno.nvim. I am not the original author of the code. I ported it to vscode/typescript and added a few features.
• This extension is still in beta. It is not expansive in any way, but it does the job simply and effectively.
• Only C++ programs on MacOS (with perf on Ubuntu) have been tested. But anything that perf can profile should work.
• Please report any issues you may find.

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Workflow

1. Generate profiling information:

perf record --call-graph dwarf ./my_program --some-arg < some_input_etc

optionally, use the following alias by adding it to your .bashrc or .zshrc:

alias perf_record="perf record --call-graph dwarf"

and run: perf_record ./my_program --some-arg < some_input_etc

Customization:

• -e flag can be used to specify the event to profile. By default, it records cpu-cycles. See perf list for a list of events.
• -F flag can be used to specify the frequency of the event. For example, -F 1000 will sample every 1000 events.
• And many more. See man perf-record for more information.

2. Generate a report:

perf report -g folded,0,caller,srcline,branch,count --no-children --full-source-path --stdio -i perf.data > perf.out

again, you can also use the following alias:

alias perf_report="perf report -g folded,0,caller,srcline,branch,count --no-children --full-source-path --stdio -i perf.data > perf.out"

and run:

perf_report

This command will always be the same. Therefore, if desired, one can chain both commands like so:

perf_record ./my_program --some-arg < some_input_etc && perf_report

3. (optional) If you are doing remote development and want to see the heatmap on your local machine, you can use scp to copy the perf.out file to your local machine. Then, run sed -i '' "s:{REMOTE_DIRECTORY}:{LOCAL_DIRECTORY}:g" "perf.out" to replace any instances of the remote directory with the local directory in the perf report.

4. Open a source file in vscode and run the perfanno.readFile (Perfanno: Read File) command using the command palette. Select the perf.out file generated in the previous step. Success!

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Extension Commands

• perfanno.readFile: Prompts for a file and annotates buffers with with the perf information.
• perfanno.pickEvent: Select a perf event to annotate.
• perfanno.clearHighlights: Clears all annotations and highlights.
• perfanno.highlight: Highlights the current line. Used to test certain highlighter capabilities.

Extension Settings

• perfanno.file: Perf datafile to search for by default. Will prompt with finder if file does not exist. Can be a file path.
• perfanno.eventOutputType: Specifies the output format for virtual text when annotating.
• perfanno.localRelative: Whether to show count relative to enclosing symbol (high sample count recommended).
• perfanno.highlightColor: The color of the highlight.
• perfanno.minimumThreshold: The minimum percentage threshold for annotating.
• perfanno.onlyLocalLeaf: Collapse each trace to its deepest in-workspace frame.

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