3 ms·

It's probably "slow" because of sdl and cgo not native Go code. A gb emulator doesn't do much actually, it's about fixed array, bit shifting, switch cases etc .

by Thaxll 4y ago

It's probably "slow" because of sdl and cgo not native Go code. A gb emulator doesn't do much actually, it's about fixed array, bit shifting, switch cases etc ... I ran a quick pprof and indeed it's spending a lot of time in cgo: Showing nodes accounting for 28720ms, 67.67% of 42440ms total Dropped 145 nodes (cum <= 212.20ms) Showing top 10 nodes out of 53 flat flat% sum% cum cum% 13080ms 30.82% 30.82% 16600ms 39.11% runtime.cgocall 4720ms 11.12% 41.94% 4750ms 11.19% main.(*RAM).get 2840ms 6.69% 48.63% 33070ms 77.92% main.(*GPU).tick 1970ms 4.64% 53.28% 3720ms 8.77% runtime.mallocgc 1450ms 3.42% 56.69% 1470ms 3.46% main.(*RAM).set 1160ms 2.73% 59.43% 41350ms 97.43% main.(*GameBoy).tick 1000ms 2.36% 61.78% 3160ms 7.45% runtime.exitsyscall 890ms 2.10% 63.88% 1610ms 3.79% main.(*CPU).tick_interrupts 820ms 1.93% 65.81% 850ms 2.00% runtime.casgstatus 790ms 1.86% 67.67% 5530ms 13.03% main.(*CPU).tick

Shish2k 4y ago
> It's probably "slow" because of sdl and cgo not native Go code The other languages are also using SDL via their respective interacting-with-C interfaces - what makes Go special here?
- Thaxll 4y ago
  Go FFI is notoriously slow. https://stackoverflow.com/questions/28272285/why-cgos-performance-is-so-slow-is-there-something-wrong-with-my-testing-code/28272990#28272990 https://stackoverflow.com/questions/28272285/why-cgos-perfor...
jbverschoor 4y ago
Yup.. a 240x performance difference (zig-py) has very little to do with the language, vm, or whatever. As soon as I saw that, I dismissed the benchmark. By these standards a 10 year old cpu with a beefy GPU will beat any new cpu as well.
- chlorion 4y ago
  What does a GPU have to do with any of this? I think you may be a little confused about something but I am not sure what.
- logicchains 4y ago
  >Yup.. a 240x performance difference (zig-py) has very little to do with the language, vm, or whatever. It absolutely does. A simple for loop in the standard Python interpreter will literally take 100x longer than the same thing in a language like C/C++, try for yourself if you don't believe me. CPython is unbelievably slow.
  - jbverschoor 4y ago
    Very interesting... Simple loop (0 -> 320000000) and add 1 to a variable. I couldn't reproduce 100x (no optimization flags, otherwise it won't do anything) Apple clang version 14.0.0 (clang-1400.0.29.102) -> 0m0.347s ruby 3.1.2p20 -> 0m11.314s Python 3.8.12 -> 0m19.662s So ruby is almost 60% faster, but the C version is "only" 32x faster than ruby. 55x python. I thought the differences would be smaller these days
chlorion 4y ago
The author stated that the benchmarks run in headless mode, so I am not sure that it's SDL that's slowing it down here. Even if it is SDL slowing it down, Go FFI being slow is still a real disadvantage compared to the other languages, and you can't just pretend like it doesn't exist in this case.

by Thaxll 4y ago

Shish2k 4y ago

> It's probably "slow" because of sdl and cgo not native Go code The other languages are also using SDL via their respective interacting-with-C interfaces - what makes Go special here?

Thaxll 4y ago
Go FFI is notoriously slow. https://stackoverflow.com/questions/28272285/why-cgos-performance-is-so-slow-is-there-something-wrong-with-my-testing-code/28272990#28272990 https://stackoverflow.com/questions/28272285/why-cgos-perfor...

jbverschoor 4y ago

Yup.. a 240x performance difference (zig-py) has very little to do with the language, vm, or whatever. As soon as I saw that, I dismissed the benchmark. By these standards a 10 year old cpu with a beefy GPU will beat any new cpu as well.

chlorion 4y ago
What does a GPU have to do with any of this? I think you may be a little confused about something but I am not sure what.
logicchains 4y ago
>Yup.. a 240x performance difference (zig-py) has very little to do with the language, vm, or whatever. It absolutely does. A simple for loop in the standard Python interpreter will literally take 100x longer than the same thing in a language like C/C++, try for yourself if you don't believe me. CPython is unbelievably slow.
- jbverschoor 4y ago
  Very interesting... Simple loop (0 -> 320000000) and add 1 to a variable. I couldn't reproduce 100x (no optimization flags, otherwise it won't do anything) Apple clang version 14.0.0 (clang-1400.0.29.102) -> 0m0.347s ruby 3.1.2p20 -> 0m11.314s Python 3.8.12 -> 0m19.662s So ruby is almost 60% faster, but the C version is "only" 32x faster than ruby. 55x python. I thought the differences would be smaller these days

chlorion 4y ago

The author stated that the benchmarks run in headless mode, so I am not sure that it's SDL that's slowing it down here. Even if it is SDL slowing it down, Go FFI being slow is still a real disadvantage compared to the other languages, and you can't just pretend like it doesn't exist in this case.