Stream: git-wasmtime

Topic: wasmtime / issue #7731 Performance issue related to float...

Wasmtime GitHub notifications bot (Dec 28 2023 at 14:12):

ShuyaoJiang opened issue #7731:

Summary

Hi, I ran the attached case (C program, compiled to Wasm by Emscripten) in different Wasm runtimes, and found abnormal performance in Wasmtime compared with three other runtimes. The execution time of this case (time interval from the start to the end of the execution of Wasm bytecode running command) on different runtimes is as follows:

• Wasmtime: 3057ms
• Wasmer: 920ms
• WasmEdge (AOT): 759ms
• WAMR (AOT): 754ms

Emscripten

• emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.49 (04a0cad4d4c9f5d62876821274d78cd0a52427af)
  clang version 18.0.0 (https://github.com/llvm/llvm-project 269685545e439ad050b67740533c59f965cae955)
  Target: wasm32-unknown-emscripten
  Thread model: posix

Wasm Runtime Version

• Wasmtime: cli 15.0.0
• Wasmer: 4.2.3
• WasmEdge (AOT): 0.13.5
• WAMR (AOT): 1.2.3

Hardware & OS

• CPU: Intel(R) Xeon(R) E5-2686 v4 CPU @ 2.30GHz
• Memory: 16GB
• OS: Ubuntu 20.04.6 LTS

Additional details

The attached source program is synthesized by a Csmith seed and a code snippet of floating-point (FP) arithmetic. The inserted code snippet is on line 946-1039 of the source program. We found that this abnormal performance would not occur when running the seed program alone. So, we believe that this anomaly may be caused by some improper handling of FP arithmetic. Could you please check this situation? Thank you!

1702437936230.zip

Wasmtime GitHub notifications bot (Jan 02 2024 at 19:57):

fitzgen commented on issue #7731:

Thanks for the bug report. Could you also separate timing of compilation vs execution for this bug as well? Thanks!

Wasmtime GitHub notifications bot (Jan 24 2024 at 23:37):

alexcrichton commented on issue #7731:

It's been awhile since this was last opened, but I wanted to be sure to drop in to say thanks for the detailed report, it's appreciated!

I was able to reproduce this and I think I fixed at least some part of the slowdown in https://github.com/bytecodealliance/wasmtime/pull/7818. I haven't dug too much further though.

Wasmtime GitHub notifications bot (Jan 24 2024 at 23:57):

alexcrichton commented on issue #7731:

I thought that there may be another source of slowdown here but after studying the program a bit more I think that at least everything I know of should be fixed with #7818. I know it's been awhile, but @ShuyaoJiang if you're still interested if you could confirm that #7818 fixes the slowdown you're seeing as well that'd be great!

Last updated: Nov 22 2024 at 16:03 UTC