I was comparing implementations of aerial distance: module GeoCalculator EARTH_RADIUS_IN_KM = 6371.0 def self.aerial_distance(from, to) dlat = to.lat - from.lat dlon = to.lon - from.lon a = Math.sin(dlat/2.0)**2 a += Math.cos(from.lat)*Math.cos(to.lat)*(Math.sin(dlon/2.0)**2)…

Struct is allocated on stack so function has direct access to value. Object is always pointer to the allocated memory so it must be dereferenced before using it. It adds up so this is why struct is faster. But I don’t think that it should be that big difference. I’d expect 10-15% difference but no…

[image] ComputerMage: Object is always pointer to the allocated memory so it must be dereferenced before using it. It adds up so this is why struct is faster. Yeah, that was the clear difference, but, as you said, the factor 3x seemed too much. Also, that 3x includes all the math! How long …

I don’t have an answer but I know LLVM is pretty good at optimizing code with structs (scalar values). Maybe one would have to compare the generated llvm IR code, or run the code through a profiler, to draw conclusions.

@fxn I’m not sure if you are aware of the Benchmark - github.com/crystal-lang/crystal module it’s handy to compare implementations. [image] fxn: compile with --release (don’t know if that is relevant) The --release is important :-) You can check the llvm-ir code if you want: $ crystal buil…

I tried to isolate struct vs class access with this simple benchmark: require "benchmark" class C getter :x, :y def initialize(@x : Float32, @y : Float32) end end c1 = C.new(1.0, 2.0) c2 = C.new(3.0, 4.0) struct S getter :x, :y def initialize(@x : Float32, @y : Float32) end end s1…

[image] bcardiff: @fxn I’m not sure if you are aware of the https://crystal-lang.org/api/0.33.0/Benchmark.html module it’s handy to compare implementations. Yep, thanks! The way the code is written (eg explicit ivar assignment) is influenced because I was comparing Ruby vs Crystal. I compare…

The thing with that benchmark is that those local variables are used by Benchmark, which captured the block and so the vars become closured and allocated on the heap. It’s very hard to benchmark.

Awesome!!! That connects with something I wondered: if all blocks are inlined, what happens with vars that belong originally to the outer scope (closured)? Probably related?

Can you compile your code with --emit=llvm-ir and send here .ll file? also compile it with --emit=asm and also attach .s file. I want to see what asm code is generated from .ll file.

The original one with aerial_distance?

Performance struct vs class

ComputerMage February 16, 2020, 1:28am 14

Cool! I will compare the code and will check what da heck is going on.

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Performance struct vs class

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