Re: emacs slow on dired renaming

[Eli Zaretskii]

> From: Robert Marshall <spam@capuchin.co.uk>
> Date: Sat, 05 Apr 2014 12:09:42 +0100
> 
> > Btw, I don't understand this part of your profile:
> >
> >     - dired-in-this-tree                     10841  38%
> >      + let                                      23   0%
> >
> > This says that dired-in-this-tree takes 1/3rd of the run time.  But
> > dired-in-this-tree is just this:
> >
> >   (defun dired-in-this-tree (file dir)
> >     ;;"Is FILE part of the directory tree starting at DIR?"
> >     (let (case-fold-search)
> >       (string-match-p (concat "^" (regexp-quote dir)) file)))
> >
> > So I wonder how come it takes such a large proportion of the time.
> >
> > As another possible hint, does the number of times dired-create-files
> > is called (26704) make sense?  Do you really have such a large number
> > of files in the tree you are moving?  Can you produce a profile for
> > moving a single file (which you say takes about 2 sec)?
> >
> 
> This then (26704) - as you see from my comment about the jpg's which are
> the only files being moved - doesn't appear to make any sense - I didn't
> realise that number was the number of times the function was called. 10
> files only are being moved none of which are directories, none of them
> are links to other files

No, wait, I think I was wrong -- this is the number of times the
profiler sampling found Emacs inside the function, not the number of
calls.  But that also sounds too large, as you say you were moving 10
files with 2 sec per file.  That should give 20000 samples (one sample
each millisecond), not 26700.

> Here's moving a single file (using 'R' in a dired buffer) - the full trace 
> rather than just a
> selection from the report (again a jpg) from ~/Pictures to
> ~/Pictures/yy; 1083 calls to dired-do-rename(!). Could there be some
> recursive calls somehow, why is command-execute being called 1227 times?!
> 
> - command-execute                                                1227  97%

This is 1.2 sec, so it looks about OK.

>  - call-interactively                                            1227  97%
>   - dired-do-rename                                              1083  86%
>    - dired-do-create-files                                       1083  86%
>     - dired-create-files                                          962  76%
>      - byte-code                                                  952  75%
>       - dired-rename-file                                         766  61%
>        - dired-rename-subdir                                      568  45%
>         - dired-fun-in-all-buffers                                180  14%

According to this, dired-rename-subdir, dired-rename-file, and
dired-create-files took 70% of the time.  But I have no idea why.

Did you try turning on garbage-collection-messages?

If that doesn't give any clues, I guess the only way is to selectively
disable portions of your ~/.emacs, to find which part causes this.

Alternatively, try running "emacs -Q" for some time, and see if things
get slower there as well.