pimeys
So basically your typical network protocol is something that converts an async stream of bytes into things like Postgres Row objects. What you do then is you write a synchronous library that does the byte conversion, then you write an asynchronous library that talks with the database with async functions, but most of the business logic is sync for converting the data coming from the async pipe.
Now, this can also be done in a higher level application. You do a server that is by nature async in 2024. Write the server part in async, and implement a sync set of mapping functions which take a request coming in and returns a response. This can be sync. If you need a database, this sync set of functions maps a request to a database query, and your async code can then call the database with the query. Another set of sync functions maps the database result into http response. No need to color everything async.
The good part with this approach is that if you want to make a completely sync version of this library or application, you just rewrite the async IO parts and can reuse all the protocol business logic. And you can provide sync and async versions of your library too!
That’s why you write your protocol as a sync library, then implement the async IO separately and mapping the data over the protocol modules.
Thanks for sparking my interest on cachyos kernels and what they patch. In addition to bore, they also patch the sched_ext support!
https://github.com/CachyOS/linux-cachyos?tab=readme-ov-file#cachyos-default-kernel
Now, what this means is you can boot this kernel, then just start the scheduler from userland, e.g.
run0 scx_rustland
It uses bpf, so the scheduler switches immediately and is as fast as anything in the kernel space. What makes this rustland scheduler super interesting is how it can detect what application is currently active, and give it a full priority over anything else. So you can compile code in the background with all cores, and at the same time play a game with the best frame rate.
There are other sched_ext schedulers available, at least on nixos with the cachyos kernel I get a bunch of scx_ binaries to play with.
For nix users here, nyx flake packages and compiles the cachyos kernel:
They have a few in the main branch: https://github.com/NixOS/nixpkgs/tree/master/pkgs/os-specific/linux/kernel
I see rt and zen at least being available. Would of course be quite easy to just send them a PR for bore patches, but I think I wait for sched_ext to land instead…
Me neither. But. I think the answer is much simpler here: Microsoft doesn’t make their money with schedulers, but bundling that Office and tracking to everybody, and charging rent every month. They have way less people working on making the kernel as fast as possible, compared to Linux where:
- there are many companies running crazy workloads 24/7, and providing patches
- very talented individual hackers who have an open source kernel and can play around with things, getting that last oomph out from their system
This is why, for a pro user, Linux is an amazing platform.
It’s pretty easy to patch the kernel in NixOS:
https://git.sr.ht/~pimeys/nixos/commit/2a023c5ccc8a499dcb4ea14b0ab52c33db3f3523
It definitely feels snappier even with my 5950x. I hope this lands to mainline soon, compiling kernel for every update takes a few minutes extra.
Not yet in the Torvalds tree of Linux? There’s a ton of interesting schedulers coming when sched_ext lands to the mainline:
https://www.phoronix.com/news/sched_ext-Ahead-Of-Linux-6.12
Also, would be great if more distros would compile packages with AVX512, there’s a ton of perf left on the table:
Meanwhile these CPUs are amazing on Linux
https://www.phoronix.com/review/amd-ryzen-9950x-9900x
https://www.phoronix.com/review/amd-zen5-avx-512-9950x
For some reason Windows scheduler is not as good as the one found in the Linux kernel with the zen5.