lmb

5 ms·

1.
by lmb 1y ago
Location: London, UK / Munich, Germany Remote: No, hybrid only Willing to relocate: Maybe Technologies: Go, C, eBPF, Linux Résumé/CV: on request Email: jobs@lmb.io Systems engineer with ten years of
2.
by lmb 4y ago
Counter point from Gleixner which is worth reading for us in the peanut gallery: https://lwn.net/ml/linux-kernel/87r11qp63n.ffs@tglx/
3.
by lmb 4y ago
Missing Allen (2001) by my late father Christian Bauer https://www.youtube.com/watch?v=kOXSI_vcqK8 Around the turn of the century, my dad's good friend and longtime collaborator Allen Ross vanishes from one day to the
4.
by lmb 4y ago
We ended up with fasthash64 and lookup3 by looking for a fast hash that is easy to port to the restricted subset of C supported by eBPF with minimal changes. https://github.com/rurban/smhasher is a great resource for t
5.
by lmb 4y ago
I think we tried siphash at some point, unfortunately it's significantly slower than the two hash functions we ended up using.
6.
by lmb 4y ago
Count min sketches are really neat. A colleague at my old company used them to implement DDoS mitigations in eBPF and wrote it up: https://blog.cloudflare.com/building-rakelimit/ The code is also open source, and I&#x2
7.
by lmb 5y ago
We don't use kernel bypass anymore, it's all XDP: https://blog.cloudflare.com/l4drop-xdp-ebpf-based-ddos-mitig...
8.
by lmb 5y ago
What does tail latency for the Zig pool look like? It seems like any Task that ends up in one of the overflow queues will stay there until at some ring buffer is emptied. Put another way, during a period of more push than pop some tasks may
9.
by lmb 5y ago
What does tooling / debugging for p4 look like? How do you inspect what happens inside a p4 dataplane? Context: I work on a L4 load balancer written in ebpf / XDP. Debugging that is still too hard even thought it's all softwa
10.
by lmb 5y ago
There is a fair bit of co-evolution of the Linux BPF verifier and the BPF llvm backend. This means that the verifier is biased to do well on bytecode that is commonly emitted by clang. I can imagine that other programming languages will run
11.
by lmb 5y ago
Seems like the right move from a volunteer run project, what will the future will hold though? Artificial scarcity is always a problem. On another note, for just 20k$ I can offer you exclusive use of the xxgfzrf.dinglebop.me Public Suffix s
12.
by lmb 6y ago
You're arguing that the majority of people use the term differently than you and are therefore wrong. Sounds like the definition of technobabble to me.
13.
by lmb 6y ago
Total shot in the dark: I had a similar problem, it turned out the power supply for the router was faulty.
14.
Naïve Art(en.wikipedia.org)
4 points by lmb 6y ago|0 comments
15.
by lmb 7y ago
Can you define ready? The functionality of the library is solid, it's based on code we're using in production. We've not committed to a stable API however. (I'm one of the maintainers of said library.)
16.
by lmb 7y ago
In some of the code snippets, the following is used: threshold = -bound % bound I don't understand how that isn't always zero. What am I missing?
17.
by lmb 7y ago
The problem is that different kernel configurations end up changing the layout of important data structures. Basically, you need to change the offsets that the eBPF uses. There is another proposal that uses BTF to do the fixup at load (not
18.
by lmb 7y ago
It doesn't give any specifics. "2 of 121 parameters were configured incorrectly". Maybe host and port? ;)
19.
by lmb 7y ago
What do you mean with this? Refuse ANY is now a proposed RFC https://datatracker.ietf.org/doc/rfc8482/ How is that a band aid?
20.
by lmb 8y ago
We've been using LMDB at Cloudflare to store small-ish configuration data, it has been rock solid. Thank you and the rest of the contributors for such a great library.
21.
by lmb 8y ago
LMDB is not a great fit for something like the WAL, where new data is written at the end, and old data discarded at the start. It leads to fragmentation (especially if WAL entries are larger than a single page).
22.
by lmb 8y ago
Can you give an idea how big your cluster is? 10, 10s, 100s? I'm curious how well Normand works in reality, but it's hard to find ppl running it.
23.
by lmb 8y ago
The byte code is used as a target for verification, and is designed to be easily JITable on x86 and arm. There are network cards which offer eBPF offload, but they only implement a subset of features available in the kernel. I imagine that
24.
by lmb 8y ago
A colleague of mine did a performance deep dive as well: https://blog.cloudflare.com/arm-takes-wing/ It's sad to see Qualcomm ditch such a good platform.
25.
by lmb 8y ago
Ok, I've looked at the code, and based on that I think what I said in my original post is correct. GLB is more complex, but will maintain connections in more circumstances.
26.
by lmb 8y ago
If the connection tracking state is really not required I don't understand how Katran works. How does it deal with the set of live backends changing? Using Maglev hashing gives you "minimal disruption", not no disruption.
27.
by lmb 8y ago
I haven't looked at what Google has released, but there are big differences between GLB and Katran. (Not affiliated with any of those companies) In terms of technology, Katran uses XDP and IPIP tunnels, both upstream in the Linux kerne
28.
by lmb 8y ago
That repo encourages mindless microoptimization. Don't waste your time worrying how to iterate a slice. Most of the time it makes no difference.
29.
by lmb 8y ago
It is possible to pass file descriptors using os/exec, using the ExtraFiles attribute [1]. No need drop down to os.StartProcess. 1: https://golang.org/pkg/os/exec/#Cmd
30.
by lmb 9y ago
There is so called "bulletproof" hosting which usually includes being able to spoof IP. So yes, there are economic incentives.

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