pwru
parca-agent
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pwru | parca-agent | |
---|---|---|
7 | 10 | |
2,464 | 480 | |
6.9% | 8.0% | |
9.1 | 9.9 | |
2 days ago | 1 day ago | |
C | Go | |
Apache License 2.0 | Apache License 2.0 |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
pwru
- GitHub - cilium/pwru: Packet, where are you? -- eBPF-based Linux kernel networking debugger
- cilium/pwru: Packet, where are you? -- eBPF-based Linux kernel networking debugger
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Packet, where are you? – eBPF-based Linux kernel networking debugger
if you have a recent enough kernel, this change https://github.com/cilium/pwru/pull/148 means that it will print the reason the packet was dropped in the output - see https://lwn.net/Articles/885729/
There's a whole heap of reasons a packet can be dropped:
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A list of new(ish) command line tools – Julia Evans
[pwru](https://github.com/cilium/pwru) is a fun new tool from the Cilium folks for tracing network packets in the kernel. Like tcpdump but it shows you the full path including kernel syscalls. Lets you debug much deeper than "when the packet gets to this port it gets dropped".
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Better visibility into Linux packet-dropping decisions
I recently came across another useful utility for debugging unexpected packet drops - PWRU[0] (Packet, Where Are You) by Cilium.
It uses eBPF to try to trace the path of the packet through the kernel. Haven't needed to use it yet, but it could have saved me a lot of trouble in the past.
[0]: https://github.com/cilium/pwru
parca-agent
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Flameshow: A Terminal Flamegraph Viewer
If that's true, you should probably update the docs. Everything I could find implied dotnet, jvm, python were still unsupported. For example, the roadmap section of the readme mentions most of these but nothing mentions dotnet. However I did find your tickets and a demo being merged in which makes it seem maybe supported?
Ticket: https://github.com/parca-dev/parca-agent/issues/161
Demo: https://github.com/parca-dev/parca-demo/pull/18
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How to troubleshoot memory leaks in Go with Grafana Pyroscope
Couldn't see any advantages to this over https://github.com/parca-dev/parca-agent. Which uses eBPF so it can be used with non-instrumented apps and code paths.
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Frame pointers vs. DWARF – my verdict
The pervasive lack of frame pointers is the reason why we've developed a custom format derived from DWARF unwind information thanks to some insights: DWARF unwind information is incredible flexible, it supports many arches and allows restoring any arbitrary register. But we only need 3: the frame pointer, the stack pointer, and in non-x86 the return address.
In addition, this encoding doesn't use that many bytes, but unfortunately reading and parsing that information is quite expensive.
For that reason I've developed a new unwinder that uses custom unwind information derived from DWARF (https://www.polarsignals.com/blog/posts/2022/11/29/profiling..., previously discussed in https://news.ycombinator.com/item?id=33788794) that runs in BPF. This new compact representation can be binary searched easily and each unwind row has a size of 16 bytes. I are currently working on reducing it down to ~10 bytes.
All the code is fully OSS (Apache 2.0 for userspace and GPL for BPF), and part of the Parca project (https://github.com/parca-dev/parca-agent).
We've also given some talks in FOSDEM going deeper into how we made it scale for many big processes.
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Dwarf-Based Stack Walking Using eBPF
I find this surprising! Was this for off the shelf applications or some custom binaries?
As mentioned above, we see DWARF expressions such as `DW_CFA_def_cfa_expression` on the regular. See the "Test Plan" section and commit messages of the PR that introduced support for this particular opcode [0]
[0]: https://github.com/parca-dev/parca-agent/pull/1058
- Parca Agent rewrites eBPF in-kernel C code in Rust (using Aya-rs)
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Fantastic Symbols and Where to Find Them - Part 2
Let's see an example perf map file for NodeJS. The runtimes out there output this file with more or less the same format, more or less!
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Fantastic Symbols and Where to Find Them - Part 1
The good news is we got you covered. If you are using Parca Agent, we already do the heavy lifting for you to symbolize captured stack traces. And we keep extending our support for the different languages and runtimes.
What are some alternatives?
fsmon - monitor filesystem on iOS / OS X / Android / FirefoxOS / Linux
kubectl-flame - Kubectl plugin for effortless profiling on kubernetes
libbpf - Automated upstream mirror for libbpf stand-alone build.
ebpf - ebpf-go is a pure-Go library to read, modify and load eBPF programs and attach them to various hooks in the Linux kernel.
bpfcov - Source-code based coverage for eBPF programs actually running in the Linux kernel
perf-map-agent - A java agent to generate method mappings to use with the linux `perf` tool
glow - Render markdown on the CLI, with pizzazz! 💅🏻
rbspy - Sampling CPU profiler for Ruby
up - Ultimate Plumber is a tool for writing Linux pipes with instant live preview
go-profiler-notes - felixge's notes on the various go profiling methods that are available.
lnav - Log file navigator
profefe - Continuous profiling for long-term postmortem analysis