3 ms·

I’ve wondered how much those speedups are due to Rust/Go/Zig/etc, versus how much is due to being able to design the system with fresh eyes and an eye for perfo

I’ve wondered how much those speedups are due to Rust/Go/Zig/etc, versus how much is due to being able to design the system with fresh eyes and an eye for performance. JS is almost surely slower than Rust, for instance, but it’s not 10-100x in most cases, at least in this random set of benchmarks I found [0]. 0: https://programming-language-benchmarks.vercel.app/rust-vs-javascript https://programming-language-benchmarks.vercel.app/rust-vs-j...

the_duke 4y ago
Benchmarks are often not a great indicator for real world performance, especially for Javascript. Benchmarks are very constrained, repetitive and often numerical code that is executed a lot of times with similar input. This gives the JIT a lot of opportunity to optimise and specialise for specific types. These tools are usually not long-running , so code has to be JITed all over again on each invocation. A lot of code will probably only be executed a few times, so might only be executed by the interpreter or low tier JIT. There will also be a lot of AST construction, walking and modification, which is really difficult to optimise without the guidance of types. A lower level language can use better data structures that don't require so much pointer chasing. Also lots of potential GC pressure if there are multiple internal representations to construct. JS can be insanely fast for what it is, but alot of the weaknesses are apparent with short-running tooling. There is also a reason why most complex,JS heavy web apps seem to get laggy and slow eventually...
TakeBlaster16 4y ago
A major benefit of Rust/Go/Zig is control over data layout. If your language doesn't have value types, the CPU spends a lot of time pointer chasing and trashes the cache. In the worst case a cache miss could have the CPU sitting idle for hundreds of clock cycles while it waits for a RAM fetch to finish. That has a big effect in large programs with many layers of data structures, but it's not usually captured in microbenchmarks.
terafo 4y ago
As already mentioned in neighboring comment, these languages give you control over data layout. But what's really powerful - is that control over layout opens up a possibility of using SIMD instructions, which by itself may have 10x speed up over optimized scalar code in the same languages, speed up over JS is, of course, greater.

the_duke 4y ago

Benchmarks are often not a great indicator for real world performance, especially for Javascript. Benchmarks are very constrained, repetitive and often numerical code that is executed a lot of times with similar input. This gives the JIT a lot of opportunity to optimise and specialise for specific types. These tools are usually not long-running , so code has to be JITed all over again on each invocation. A lot of code will probably only be executed a few times, so might only be executed by the interpreter or low tier JIT. There will also be a lot of AST construction, walking and modification, which is really difficult to optimise without the guidance of types. A lower level language can use better data structures that don't require so much pointer chasing. Also lots of potential GC pressure if there are multiple internal representations to construct. JS can be insanely fast for what it is, but alot of the weaknesses are apparent with short-running tooling. There is also a reason why most complex,JS heavy web apps seem to get laggy and slow eventually...

TakeBlaster16 4y ago

A major benefit of Rust/Go/Zig is control over data layout. If your language doesn't have value types, the CPU spends a lot of time pointer chasing and trashes the cache. In the worst case a cache miss could have the CPU sitting idle for hundreds of clock cycles while it waits for a RAM fetch to finish. That has a big effect in large programs with many layers of data structures, but it's not usually captured in microbenchmarks.

terafo 4y ago

As already mentioned in neighboring comment, these languages give you control over data layout. But what's really powerful - is that control over layout opens up a possibility of using SIMD instructions, which by itself may have 10x speed up over optimized scalar code in the same languages, speed up over JS is, of course, greater.