Nix Profiling: Difference between revisions

Revision as of 06:34, 3 March 2026

Nix-darwin

First, run the following to get a flamegraph:

# This assumes that you've named your nix-darwin configuration
# after your hostname
nix eval --option eval-profiler flamegraph .#darwinConfigurations.$(hostname).system

You should end up with a file called nix.profile:

$ file nix.profile nix.profile: Unicode text, UTF-8 text, with very long lines (1339

Make flamegraph

This zoomed out screenshot of `nix.svg` shows what kind of image you should expect to come out of the `flamegraph` tool for a `nix eval` run on `nix-darwin`.

Use the flamegraph package to render this nix.profile file to a SVG image:

$ flamegraph < nix.profile > nix.svg

On my system, this creates a 3.5 MiB SVG file.

@@ Line 4: / Line 4: @@
 # after your hostname
 nix eval --option eval-profiler flamegraph .#darwinConfigurations.$(hostname).system
+</pre>You should end up with a file called <code>nix.profile</code>:<pre>
+$ file nix.profile
+nix.profile: Unicode text, UTF-8 text, with very long lines (1339
 </pre>
+=== Make flamegraph ===
+[[File:Nix eval flamegraph.png|thumb|This zoomed out screenshot of <code>nix.svg</code> shows what kind of image you should expect to come out of the <code>flamegraph</code> tool for a <code>nix eval</code> run on <code>nix-darwin</code>.]]
+Use the flamegraph package to render this <code>nix.profile</code> file to a SVG image:<pre>
+$ flamegraph < nix.profile > nix.svg
+</pre>On my system, this creates a 3.5 MiB SVG file.