Running Windows exe from WSL is slower than from native Windows

[lucidfrontier45]

Version

Microsoft Windows [Version 10.0.22621.675]

WSL Version

• WSL 2
• WSL 1

Kernel Version

5.15.57.1

Distro Version

Ubuntu 22.04

Other Software

No response

Repro Steps

1. sudo apt install mingw-w64
2. download https://gist.github.com/lucidfrontier45/c83a58ff423f26dc0feb9ce84ea8f836#file-main2-cpp and save as main.cpp
3. x86_64-w64-mingw32-g++ -O3 --std=c++17 --static main.cpp
4. put compiled a.exe to /mnt/c
5. run /mnt/c/a.exe from WSL Ubuntu terminal
6. run C:\a.exe from Windows Powershell terminal

Expected Behavior

5 and 6 end in the same duration

Actual Behavior

6 is twice slower than 5.

Diagnostic Logs

No response

related #8943

[lucidfrontier45]

This does not happen for the stock WSL (kernel 5.10.102.1)

[ghost]

endl causes a flush. Meaning you have synchronous write output blocking forward progress.

I'm closing this as designed. We could bump buffer sizes, but I doubt that would do much here.

[lucidfrontier45]

@pmartincic

Hi. endl flush is done only once at the end, not inside the for loop. I don't understand why it cause the performance drop.

I also mentioned in the comment that this problem doesn't happen on the stock WSL (kernel 5.10.102.1). Is it really as designed ?

[ghost]

Are you running a custom kernel?

[lucidfrontier45]

@pmartincic

The stock WSL (kernel 5.10.102.1) does not have this problem.
After running wsl --update in powershell, the kernel became 5.15.57.1 and this problem happened.

[ghost]

Depending on what the application does there is always going to be some hit on performance by running through wsl.

However, if you're telling me that you updated WSL, and then saw a performance decrease, with no custom kernel. Then there is probably something for us to look at.

[lucidfrontier45]

However, if you're telling me that you updated WSL, and then saw a performance decrease, with no custom kernel.

Yes, that's exactly what I am saying.

[DoctorWho8]

@lucidfrontier45 what did you do to update your kernel from 5.10.102.1 to 5.15.57.1?

I've got:
PS C:\Users\hanso\OneDrive\Desktop> wsl --update
Checking for updates...
No updates are available.
Kernel version: 5.10.102.1
And that's from running things inside PowerShell both normal levels and Admin levels.

[lucidfrontier45]

@DoctorWho8 I just did wsl --update in normal level PowerShell. After it now I have WSL 0.70.4.0 with Kernel 5.15.68.1. Previously wsl --update results in WSL 0.66.2 and Kernel 5.15.57.1. Both WSL/Kernel version have the reported problem. Only the stock WSL before applying wsl --update doesn't have the problem but I don't know its exact version since wsl --version doesn't work in the stock WSL.

Below are the logs (in Japanese)

PS C:\Users\lucid> wsl --update
インストール中: Linux 用 Windows サブシステム
Linux 用 Windows サブシステム はインストールされました。 (Windows subsystem for Linux is installed)
PS C:\Users\lucid> wsl --version
WSL バージョン: 0.70.4.0 (WSL version)
カーネル バージョン: 5.15.68.1 (Kernel version)
WSLg バージョン: 1.0.45
MSRDC バージョン: 1.2.3575
Direct3D バージョン: 1.606.4
DXCore バージョン: 10.0.25131.1002-220531-1700.rs-onecore-base2-hyp
Windowsバージョン: 10.0.22621.675

[microsoft-github-policy-service]

This issue has been automatically closed since it has not had any activity for the past year. If you're still experiencing this issue please re-file this as a new issue or feature request.

Thank you!