Don't use musl if you care about performance

https://blog.brokk.ai/dont-use-musl-if-you-care-about-performance/

23•jbellis•2h ago

Comments

grep_it•56m ago

I think the size of linked binaries and simplicity were always the main features?

Joker_vD•45m ago

Yeah... I've recently had a chance to compare how fgets is implemented in both GNU libc and musl, and, well. With glibc, it was a challenge to even find where the fgets's code actually is.

marssaxman•52m ago

People have such different perspectives. 26% slower does not sound "terrible" to me; it sounds like quite a reasonable price one might choose to pay for the convenience musl offers. If musl's allocator were 2.6x slower, I might call that "not so great"... but in order to qualify as "terrible" I think the difference would have to be an order of magnitude!

loeg•24m ago

The 26% number at the top of the article is from using mimalloc (which is a high performance allocator, at least as fast as the glibc allocator) + musl for some task, and the slowdown is coming from (probably) slow musl implementations of memcpy/memset. The musl allocator is even worse.

delduca•51m ago

Also musl is not a complete runtime

OptionOfT•48m ago

Are there other options if I want to ship a 'FROM scratch' image with just a single Rust executable, and everything compiled in?

That to me is the main driver for MUSL.

nazgulsenpai•30m ago

Same usecase here, I use musl for compiling self contained Nim utilities I use on containers and servers without having to deal with glibc hell.

desdenova•24m ago

Most of musl's performance issues come from their allocator. Using it with a third party high performance allocator allows you to benefit from static linking with very little performance loss.

loeg•20m ago

> Most of musl's performance issues come from their allocator. Using it with a third party high performance allocator allows you to benefit from static linking with very little performance loss.

This is addressed and disputed very early in the article. The very first benchmark presented shows a 26% regression using musl + mimalloc, a high-performance 3rd party allocator.

bloppe•23m ago

This is only one aspect of "performance". glibc's allocator may be faster, but it also uses more memory.

For a much more technical discussion, see https://github.com/sharkdp/fd/issues/710

mattrighetti•15m ago

Posted this the other day but the whole musl allocator thing seems to be well known [0]

[0]: https://news.ycombinator.com/item?id=45143347

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