GNU bug report logs - #16830
[Bug] 24.3.50; massive slow down in forward-line

Previous Next

Full log

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Stefan-W. Hahn" <stefan.hahn <at> s-hahn.de>
To: bug-gnu-emacs <at> gnu.org
Subject: [Bug] 24.3.50; massive slow down in forward-line
Date: Fri, 21 Feb 2014 13:16:07 +0100

Good day,

I have measured a massive slow down for emacs24 on windows. I struggled
while using org-mode columnview, which takes for a short table several
minutes compared to a second with an older versino of emacs.

I tried to dig it down:

Running on an Core I7 Laptop with Windows 7/64 bit,
starting "emacs -q"

I got the  following times (elp measurement) for the org-mode function
org-goto-line:

Emacs 24.3.1 is ok, on Emacs 24.3.50 (I tested
https://www.dropbox.com/sh/3pgcb3iiy8s9irl/77pwM1O-5K/emacs-20140217-r116465-bin-i386.zip
) got a slow down of factor 10!!

org-goto-line (24.3.1)
test-org-goto-line  1           0.2           0.2
forward-line        10000       0.0640000000  6.40...e-006
widen               10000       0.003         3e-007
goto-char           10001       0.002         1.99...e-007

org-forward-line with narrow (24.3.1)
test-forward-line  1           0.042         0.042
forward-line       10000       0.003         3e-007
goto-char          1           0.0           0.0

org-forward-line without narrow (24.3.1)
test-forward-line  1           0.046         0.046
forward-line       10000       0.007         7e-007
goto-char          1           0.0           0.0


org-goto-line (24.3.50.1)
test-org-goto-line  1           2.141         2.141
forward-line        10000       1.8479999999  0.0001847999
goto-char           10001       0.006         5.99...e-007
widen               10000       0.005         5e-007

org-forward-line with narrow (24.3.50.1)
test-forward-line  1           0.102         0.102
forward-line       10000       0.0160000000  1.60...e-006
goto-char          1           0.0           0.0

org-forward-line without narrow (24.3.50.1)
test-forward-line  1           0.125         0.125
forward-line       10000       0.005         5e-007
goto-char          1           0.0           0.0

Problem seemss to be forward-line.

Tested with following test case:

#+BEGIN_SRC elisp
(defsubst my-org-goto-line (N)
  (save-restriction
    (widen)
    (goto-char (point-min))
    (forward-line (1- N))))

(defun test-org-goto-line ()
  (with-temp-buffer
    (open-line 10000)
    (goto-char (point-min))
    (narrow-to-region (point-min) (point-max))
    (dotimes (i 10000)
      (my-org-goto-line i)
      )
    )
  )

(defun test-forward-line (with-narrow)
  (with-temp-buffer
    (open-line 10000)
    (goto-char (point-min))
    (if with-narrow
        (narrow-to-region (point-min) (point-max)))
    (dotimes (i 10000)
      (forward-line 1)
      )
    )
  )

(defvar test-buffer nil)
(defun test-performance/org-goto-line ()
  (interactive)
  (elp-instrument-list '(test-org-goto-line forward-line goto-char widen))
  (test-org-goto-line)
  (let ((elp-recycle-buffers-p nil)
        rc)
    (elp-results)
    (setq rc (buffer-string))
    (kill-buffer)
    (with-current-buffer test-buffer
      (insert "org-goto-line ("
              emacs-version
              ")\n")
      (insert rc "\n"))
    )
  (elp-restore-all)
)

(defun test-performance/forward-line (with-narrow)
  (interactive)
  (elp-instrument-list '(test-forward-line forward-line goto-char widen))
  (test-forward-line with-narrow)
  (let ((elp-recycle-buffers-p nil)
        rc)
    (elp-results)
    (setq rc (buffer-string))
    (kill-buffer)
    (with-current-buffer test-buffer
      (insert (format "org-forward-line %s (" (if with-narrow "with narrow" "without narrow"))
              emacs-version
              ")\n")
      (insert rc "\n")))
  (elp-restore-all)
)

(defun test-performance ()
  (interactive)
  (setq test-buffer (generate-new-buffer "*Performance*"))
  (test-performance/org-goto-line)
  (test-performance/forward-line t)
  (test-performance/forward-line nil)
  (pop-to-buffer test-buffer))
#+END:

With kind regards,
Stefan

-- 
Stefan-W. Hahn                          It is easy to make things.
                                        It is hard to make things simple.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.