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I wonder if this will fix the slow IO in WSL2 reading from Windows (/mnt/c), since WSL2 also uses 9p

No, since WSL2 is based on the Windows hypervisor/emulator Hyper-V, not QEMU/KVM.

But when you access files on Windows from WSL2 (e.g., under /mnt/c), the same 9P protocol is being used

Unless Microsoft is violating the GPL they aren't using the same code as QEMU for 9P.

Same protocol, but the implementation is at the discretion of whoever writes the server code.

For example I went to check and in crosvm we use a BTreeMap already for Fids for our p9 implementation (thankfully): https://github.com/google/crosvm/blob/main/common/p9/src/ser...

Right but this fix was on the “qemu 9p server”.

On WSL you would be using the “hyperv 9p server”.

Same Linux 9p client in both cases but that’s not where the fix was.

Reasonable question but the answer is still no.

From commit: > The previous implementation would iterate over the fid table for lookup operations, resulting in an operation with O(n) complexity on the number of open files and poor cache locality -- for every open, stat, read, write, etc operation.

Windows's file handling also is very slow at times (especially Windows Explorer has frustrating UX).

We can ask MS to release all their source and we will then fix all O(n) issues for them.

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