Why is stat slow?
Eliot Moss via Cygwin <[email protected]>
| Newsgroups | gmane.os.cygwin |
|---|---|
| Message-ID | <[email protected]> |
Dear Cygwin-ers -- 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 (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 A second run shortly after the first completes very quickly, indicating the presence of a cache :-) . time stat <the files> on WSL2 gives: real 0m2.208s user 0m0.026s sys 0m0.149s This is after a reboot, so there is no caching available. So, why is Cygwin 60 times slower, even when WSL2 has the handicap of having to work through the 9p adapter / COM surrogate? Mostly I am curious, but this is also relevant because I rsync this file collection to offsite storage, and the stat time is about what it takes for rsync to start up - it needs to check file times and lengths. This makes me wonder if there is something we can do to make this better, by figuring out what WSL2 / 9p are doing ... Best - Eliot Moss -- 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