Cygwin Filesystem Performance degradation 1.7.5 vs 1.7.7, and methods for improving performance

Corinna Vinschen
Thu Oct 7 16:14:00 GMT 2010

On Oct  7 17:31, Derry Shribman wrote:
> Hi,
> On 10/7/2010 3:45 PM, Corinna Vinschen wrote:
> > Well, just an idea.  I'm also still mulling over a good caching
> > method to speed up `ls -l'.  The worst problem is still that `ls -l'
> > calls getacl on all files.  In case of using POSIX permissions (default
> > "acl" mount), this potentially requires to open all files three times.
> > Since we already have the ACL from the lstat call, it's kind of a pity
> > that we don't reuse it in the subsequent getacl calls.
> May a 'generic cygwin cache' cound be added later on, for caching
> paths to 'extra cygwin/POSIX info' (st_nlink, st_ino, ACL, symlink
> magic, exectuable magic, filesystem info).

Yes, in theory.  The problem which we have to keep in mind is that
caching file meta information for any longer period of time can very
quickly result in wrong information, which in turn can result in subtile
misbehavior on the application level.  This would be very hard to track
down since it's almost impossible to reproduce.  We are not the OS, so
we never have real control over all file access.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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