Re: NT directory traversal speed on 25K files on Cygwin

On Mon, Feb 27, 2006 at 10:19:09AM +0100, Andreas Ericsson wrote:

Rutger Nijlunsing wrote:

quoted

On Sun, Feb 26, 2006 at 02:55:52PM -0500, Christopher Faylor wrote:

quoted

On Thu, Feb 23, 2006 at 03:07:07PM +0100, Alex Riesen wrote:

quoted

filesystem is slow and locked down, and exec-attribute is NOT really
useful even on NTFS (it is somehow related to execute permission and
open files.  I still cannot figure out how exactly are they related).

Again, it's not clear if you're talking about Windows or Cygwin but
under Cygwin, in the default configuration, the exec attribute means the
same thing to cygwin as it does to linux.

I don't know about native Windows speed, but comparing NutCracker with
Cygwin on a simple 'find . | wc -l' already gives a clue that looking
at Cygwin to benchmark NT file inspection IO will give a skewed
picture:

Well, naturally. Cygwin is a userland implementation of a sane 
filesystem on top of a less sane one. File IO is bound to be slower when 
one FS is emulated on top of another. I think cygwin users are aware of 
this and simply accept the speed-for-sanity tradeoff. I know I would.

MKS NutCracker tries to solve the same issues as Cygwin tries to
solve. But maybe less sane, I don't know. But a simple 'find' is
several times faster than a Cygwin 'find'. Yes, very
unscientific. Just as unscientific as 'git is slow on Windows,
therefore Windows IO is slow'.

I'm not saying Cygwin is bad (actually, I'm installing on every
Windows PC I get my hand on ;), but using Cygwin for all file IO
instead of native Windows IO makes git a magnitude slower on Windows
than could-be. So a small portability layer with a function like
'given all filenames with all mtimes' might help, or we could look at
why Cygwin is slower in this case. Alas my Windows profiling skills
aren't that good...

Regards,
Rutger.

-- 
Rutger Nijlunsing ---------------------------------- eludias ed dse.nl
never attribute to a conspiracy which can be explained by incompetence
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