Very slow IO with WSL2 even on SSD. Example: updatedb

[danielniccoli]

• Your Windows build number: Microsoft Windows [Version 10.0.19018.1]
• What you're doing and what's happening:

WSL 2 installed on a SSD. Running updatedb.
It takes 6 minutes the first time and 2 minutes the second run. On an SSD this should take a couple of seconds at most, at least for the second run.

root@BORKASON:~# time updatedb

real    5m50.360s
user    0m7.647s
sys     0m50.115s
root@BORKASON:~# time updatedb

real    1m55.429s
user    0m2.723s
sys     0m16.396s

• What's wrong / what should be happening instead:
  On an SSD this should take a couple of seconds at most.

[onomatopellan]

Try adding /mnt to the PRUNEPATHS variable in /etc/updatedb.conf

Accessing /mnt files in WSL2 is slow right now #4197

[therealkenc]

Try adding /mnt to the PRUNEPATHS variable in /etc/updatedb.conf

That's the catch. I didn't consider updatedb(8) would traipse all over /mnt (an strace log would have made that obv). Thanks!

[late ed] Odd though. Having something big and slow on /mnt in Real Linux isn't an unusual scenario; I have a slow USB backup drive on mine. "Forgetting" (scare quote) to tweak /etc/updatedb.conf is probably pretty common too. Never seen it take 5min tho.