Re: Why is stat slow?
Eliot Moss via Cygwin <[email protected]>
| Newsgroups | gmane.os.cygwin |
|---|---|
| Message-ID | <[email protected]> |
On 12/22/2025 10:07 AM, Christian Franke via Cygwin wrote: > Eliot Moss via Cygwin wrote: >> I'm sure this has been asked before, more than once, but I am again wondering >> what, specifically, makes stat (the program, but presumably also the syscall) >> substantially slower on Cygwin compared to stat on WSL2. I am talking about >> an external HDD (not solid state) on my D: drive. It shows under WSL 2 as >> /mnt/d like this (output of mount): >> >> D:\ on /mnt/d type 9p >> (rw,noatime,aname=drvfs;path=D:\;uid=0;gid=0;symlinkroot=/mnt/,cache=5,access=client,msize=65536,trans=fd,rfd=5,wfd=5) >> >> On Cygwin it shows up like this (yes, mount shows two lines): >> >> D: on /cygdrive/d type ntfs (binary,notexec,posix=0,user) >> D: on /cygdrive/d type ntfs (binary,noacl,posix=0,user,noumount,auto) >> >> My /etc/fstab lines are: >> >> none /cygdrive cygdrive binary,noacl,posix=0,user 0 0 >> d: /cygdrive/d ntfs binary,posix=0,user,auto,notexec 0 0 > > In the past, Cygwin did not support individual options for some /cygdrive/X. If this is still the case, "noacl" without > "notexec" is effective for /cygdrive/d. Then Cygwin reads the header of each file to check for a possible "x" permission. > > >> >> (Presumably this has something to do with two mounts showing ...) >> >> On D; I have a folder with hundreds of 2Gb files (they are backups, split into >> 2Gb portions). On Cygwin >> >> time stat <the files> gives >> >> real 2m12.425s >> user 0m0.249s >> sys 0m1.312s >> > > This would explain this long duration. > > Quick test: > > $ echo '#!/bin/sh' > /cygdrive/d/script.tmp > $ ls -l /cygdrive/d/script.tmp > -rwxr-xr-x .... <== notexec unset > -rw-r--r-- .... <== notexec set Aha! I changed my /etc/fstab to be like this: none /cygdrive cygdrive binary,noacl,posix=0,user 0 0 d: /d ntfs binary,posix=0,user 0 0 D: is still available via explicit /cygdrive/d, but that would be without the noacl option. Using /d now the previously slow stat completes in a few seconds, reasonable for going over what is now 2000 files. My memory of exactly why is dim, but the noacl seems important for my C: drive. Using the ACLs on D: to determine executability seems good. Thanks! Eliot -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple