On 12/22/2025 8:57 AM, Jakob Bohm via Cygwin wrote:
As a longtime aficionado of these issues, Cygwin/MSYS2 stat() function is inherently slower than native Linux/WSL stat() syscall, because the native stat returns data already kept and cached for each file system inode/MFTE, while the Cygwin emulation goes through a lot of hoops to synthesize similar information from a variety of file system data . The call path that uses GetFileInformationByHandle() is the closest to a native fast implementation, but unfortunately, most 21st century antivirus solutions tend to initiate a full "scan file on open to prevent passing infected data to vulnerable applications" cost when doing the proforma file open to get the file handle needed for the GetFileInformationByHandle() call or other low risk checks .
Another set of hoops in the stat() code is the synthesis of a simulated set of mode bits, which tends to bring in the entire ACL reinterpretation logic as well as detection of various symlink approximations (it would be faster to simply treat all "reparse points" as symlinks and add logic to readlink() that deals with the various native types, but that would loose the ability to create file system symlinks without the Administrator privilege of creating the more dangerous system objects also named "symlink" ).
If the false triggering of AV scanning can be avoided, streamlining the Cygwin stat() code could greatly speed up heavy users of stat() such as the find and du commands .
Thank you, Jakob! That gives me some interesting ideas. First, one of my mount lines indicates noacl, so I may be avoiding that cost. (I am still a little confused about having two mount lines and wonder which one takes precedence (or some combination?).) Concerning antivirus, maybe I can turn it off for that drive. It stores only tings I explicitly put there, which should not need scanning for safety. Regards - 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
