#perf #profiling #flamegraph

bin+lib inferno

Rust port of the FlameGraph performance profiling tool suite

7 releases (breaking)

✓ Uses Rust 2018 edition

0.6.0 Mar 13, 2019
0.5.0 Mar 13, 2019
0.4.1 Mar 11, 2019
0.3.0 Feb 21, 2019
0.1.0 Jan 27, 2019

#18 in Profiling

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Used in 1 crate



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Inferno is a port of parts of the flamegraph toolkit to Rust, with the aim of improving the performance of the original flamegraph tools. The primary focus is on speeding up the stackcollapse-* tools that process output from various profiling tools into the "folded" format expected by the flamegraph plotting tool. So far, the focus has been on parsing profiling results from perf and DTrace. At the time of writing, inferno-collapse-perf is ~9x faster than stackcollapse-perf.pl and inferno-collapse-dtrace is ~10x faster than stackcollapse.pl (see compare.sh).

It is developed in part through live coding sessions, which you can find on YouTube.


To profile your application, you'll need to have a "profiler" installed. This will likely be perf or bpftrace on Linux, and DTrace on macOS. There are some great instructions on how to get started with these tools on Brendan Gregg's CPU Flame Graphs page.

In Linux, you may need to tweak a kernel config such as

$ echo 0 | sudo tee /proc/sys/kernel/perf_event_paranoid

to get profiling to work.

How to use

As a library

Inferno provides a library interface through the inferno crate. This will let you collapse stacks and produce flame graphs without going through the command line, and is intended for integration with external Rust tools like cargo-flamegraph.

As a binary

First, install Inferno. Then, build your application (in release mode and with debug symbols). Finally, run a profiler to gather profiling data and pass it through the appropriate Inferno "collapser". Depending on your platform, this will look something like

$ # Linux
# perf record --call-graph dwarf target/release/mybin
$ perf script | inferno-collapse-perf > stacks.folded


$ # macOS
$ target/release/mybin &
$ pid=$!
# dtrace -x ustackframes=100 -n "profile-97 /pid == $pid/ { @[ustack()] = count(); } tick-60s { exit(0); }"  -o out.user_stacks
$ cat out.user_stacks | inferno-collapse-dtrace > stacks.folded

In the end, you'll end up with a "folded stack" file. You can pass that file to inferno-flamegraph to generate a flame graph SVG:

$ cat stacks.folded | inferno-flamegraph > flamegraph.svg

You'll end up with an image like this:

colorized flamegraph output


Comparison to the Perl implementation

To run Inferno's performance comparison, run ./compare.sh. It requires hyperfine, and you must make sure you also check out Inferno's submodules.

Collapsing benchmarks

Inferno includes criterion benchmarks of its stack collapser implementations in benches/. Criterion saves its results in target/criterion/, and uses that to recognize changes in performance, which should make it easy to detect performance regressions while developing bugfixes and improvements.

You can run the benchmarks with cargo bench. On my desktop computer (AMD Ryzen 5 2600X), I get these results, but YMMV:

collapse/perf           time:   [14.978 ms 14.987 ms 14.996 ms]
                        thrpt:  [199.64 MiB/s 199.76 MiB/s 199.88 MiB/s]

collapse/dtrace         time:   [9.8128 ms 9.8169 ms 9.8213 ms]
                        thrpt:  [134.24 MiB/s 134.30 MiB/s 134.36 MiB/s]


Inferno is a port of @brendangregg's awesome original FlameGraph project, written in Perl, and owes its existence and pretty much of all of its functionality entirely to that project. Like FlameGraph, Inferno is licensed under the CDDL 1.0 to avoid any licensing issues. Specifically, the CDDL 1.0 grants

a world-wide, royalty-free, non-exclusive license under intellectual property rights (other than patent or trademark) Licensable by Initial Developer, to use, reproduce, modify, display, perform, sublicense and distribute the Original Software (or portions thereof), with or without Modifications, and/or as part of a Larger Work; and under Patent Claims infringed by the making, using or selling of Original Software, to make, have made, use, practice, sell, and offer for sale, and/or otherwise dispose of the Original Software (or portions thereof).

as long as the source is made available along with the license (3.1), both of which are true since you're reading this file!


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