rustc-perf VS rfcs

> what do people use to run benchmarks on CI?

Typically, you purchase/rent a server that does nothing but sequentially run queued benchmarks (and the size/performance of this server doesn't really matter, as long as the performance is consistent), then sends the report somewhere for hosting and processing. Of course, this could be triggered by something running in CI, and the CI job could wait for the results, if benchmarking is an important part of your workflow.

But CI and benchmarks really shouldn't be run on the same host.

> What does the rust project use?

It's not clear exactly where the Rust benchmark "perf-runner" is hosted, but here are the specifications of the machine at least: https://github.com/rust-lang/rustc-perf/blob/414230abc695bd7...

> What do other projects use?

Essentially what I described above, a dedicated machine that runs benchmarks. The Rust project seems to do it via GitHub comments (as I understand https://github.com/rust-lang/rustc-perf/tree/master/collecto...), others have API servers that respond to HTTP requests done from CI/chat, others have remote GUIs that triggers the runs. I don't think there is a single solution that everyone/most are using.

A lot of effort is spent to reduce the size of structs in the Rust compiler

https://nnethercote.github.io/2023/03/24/how-to-speed-up-the...

3% and 6% of improvement doesn't seem like much, but at the level of rustc those big wins

Performance of Rustc must be continously tracked (here https://perf.rust-lang.org/) because if you don't proactively fight against bloat, the tendency is that the code will become slower over time (due to new features etc)

hmm really really hard to answer :'), it's tradeoffs I think, no matter what you think Rust (cmiiw, I'm not qualified to say this) has (and probably in the future will adds more with guards on compiler metrics https://perf.rust-lang.org/) several phases that given the diffs to other language, might not available to any language compiler out there, if it's available I think rustc already did their best in here (some already being parallized etc etc, might be wrong since I can't refs any reference MRs, but it does exists though labels regarding this)

About a year ago I was looking for a tool like Rust perf for my application code. I did some research and found a lot of prior art. However, nothing checked all the boxes I was looking for, so I built Bencher!

https://www.pingcap.com/blog/rust-compilation-model-calamity... is a good overview. In general it varies depending on the crate but we track the performance at https://perf.rust-lang.org/ - if you look at cargo, for example, over 60% of the time is spent in codegen through LLVM: https://perf.rust-lang.org/detailed-query.html?commit=222d1f...

Something like https://perf.rust-lang.org/?

The performance full-report link is dead: https://github.com/rust-lang/rustc-perf/blob/master/triage/2022-10-04.md

RFC: Add large language models to Rust

https://github.com/rust-lang/rfcs/pull/3603

Man, SO and family has really gone downhill. That top answer is absolutely terrible. In fact, if you care, you can literally look at the RFC discussion here to see the actual debate: https://github.com/rust-lang/rfcs/pull/582

Basically, `for x in y` is kind of redundant, already sorta-kinda supported by itertools, and there's also a ton of macros that sorta-kinda do it already. It would just be language bloat at this point.

Literally has nothing to do with memory management.

Congrats!

> Similarly, uv does not yet generate a platform-agnostic lockfile. This matches pip-tools, but differs from Poetry and PDM, making uv a better fit for projects built around the pip and pip-tools workflows.

Do you expect to make the higher level workflow independent of requirements.txt / support a platform-agnostic lockfile? Being attached to Rye makes me think "no".

Without being platform agnostic, to me this is dead-on-arrival and unable to meet the "Cargo for Python" aim.

> uv supports alternate resolution strategies. By default, uv follows the standard Python dependency resolution strategy of preferring the latest compatible version of each package. But by passing --resolution=lowest, library authors can test their packages against the lowest-compatible version of their dependencies. (This is similar to Go's Minimal version selection.)

> uv allows for resolutions against arbitrary target Python versions. While pip and pip-tools always resolve against the currently-installed Python version (generating, e.g., a Python 3.12-compatible resolution when running under Python 3.12), uv accepts a --python-version parameter, enabling you to generate, e.g., Python 3.7-compatible resolutions even when running under newer versions.

This is great to see though!

I can understand it being a flag on these lower level, directly invoked dependency resolution operations.

While you aren't onto the higher level operations yet, I think it'd be useful to see if there is any cross-ecosystem learning we can do for my MSRV RFC: https://github.com/rust-lang/rfcs/pull/3537

How are you handling pre-releases in you resolution? Unsure how much of that is specified in PEPs. Its something that Cargo is weak in today but we're slowly improving.

In the early days of Rust there was a debate about whether to support "green threads" and in doing that require runtime support. It was actually implemented and included for a time but it creates problems when trying to do library or embedded code. At the time Go for example chose to go that route, and it was both nice (goroutines are nice to write and well supported) and expensive (effectively requires GC etc). I don't remember the details but there is a Rust RFC from when they removed green threads:

https://github.com/rust-lang/rfcs/blob/0806be4f282144cfcd55b...

I did some more digging. By RFC 899, I believe Alex Crichton meant PR 899 in this repo:

https://github.com/rust-lang/rfcs/pull/899

Still, no real discussion of why unbuffered stderr.

Rust has had a stable SIMD vector API[1] for a long time. But, it's architecture specific. The portable API[2] isn't stable yet, but you probably can't use the portable API for some of the more exotic uses of SIMD anyway. Indeed, that's true in .NET's case too[3].

Rust does all this SIMD too. It just isn't in the standard library. But the regex crate does it. Indeed, this is where .NET got its SIMD approach for multiple substring search from in the first place[4]. ;-)

You're right that Rust's standard library is conservatively vectorized though[5]. The main thing blocking this isn't the lack of SIMD availability. It's more about how the standard library is internally structured, and the fact that things like substring search are not actually defined in `std` directly, but rather, in `core`. There are plans to fix this[6].

[1]: https://doc.rust-lang.org/std/arch/index.html

[2]: https://doc.rust-lang.org/std/simd/index.html

[3]: https://github.com/dotnet/runtime/blob/72fae0073b35a404f03c3...

[4]: https://github.com/dotnet/runtime/pull/88394#issuecomment-16...

[5]: https://github.com/BurntSushi/memchr#why-is-the-standard-lib...

[6]: https://github.com/rust-lang/rfcs/pull/3469