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

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Sep 13 13:28, Yoni Londner wrote:
> Hi,
> 
> > However, isn't that kind of a chicken/egg situation?  If you want to
> > reuse the content of the FILE_BOTH{_ID}_DIRECTORY_INFORMATION structure
> > from a previous call to readdir, you would have to call the
> 
> I am not talking about reusing info from a previous readdir.
> 
> Every single file cygwin tries to access, it does it in a loop,
> trying afterwards to check for *.lnk file.
> 
> Using the directory query operations, it is possible to get this
> info faster:
> instead of getting file info for FOO and then for "FOO.lnk",
> Cygwin can query the directory info for "FOO FOO.LNK" (for the file
> requested, plus its possible symlink file).

I don't understand how you think this should work.  The filter expression
given to NtQueryDirectoryFile is either a constant string and has to match
the filename exactly, or it contains wildcards.  This is documented
behaviour: http://msdn.microsoft.com/en-us/library/ff567047%28VS.85%29.aspx
So, "foo" works, "foo*" works, but a list like "foo foo.exe foo.lnk" 
does not.

There's also the problem of handling NFS shares.  However, I just had an
idea how to speed up symlink_info::check without neglecting NFS shares.
This will take some time, though since it turns a lot of code upside
down.  Stay tuned.


Corinna

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