Re: State of the overlay tree branch?

[Sebastian Sturm <s.sturm@arkona-technologies.de>]

On 03/19/2018 07:43 AM, Eli Zaretskii wrote:
 >> From: Sebastian Sturm <s.sturm@arkona-technologies.de>
 >> Date: Mon, 19 Mar 2018 00:20:13 +0100
 >>
 >> for the record, I just switched back to emacs master (no noverlay) and
 >> the time reported by (benchmark-run 1000 (line-number-at-pos (point))
 >> increased by a factor of ~40, to 75-80s. At this level, editing is
 >> unbearably slow. With the semantic highlighter disabled, the same
 >> measurement yields ~2.5s (still painfully slow, but borderline usable),
 >> so about the same time reported by the noverlay branch.
 >
 > You will have to explain why overlays and the semantic highlighter
 > affect line-counting.  How about presenting a profile produced by
 > "M-x profiler-report"?

please find below a profiler report taken this morning (on my PC at 
work, which doesn't suffer from the performance issue as much as my 2014 
MacBook Pro, but even here the issue is clearly noticeable)

 >
 > And the timings you measure are 2.5 _milliseconds_ (the benchmark runs
 > 1000 times), right?  If so, I cannot understand why you say that's
 > borderline usable, because IME such short times are imperceptible by
 > humans.  I guess some other factor is at work here, so I'd suggest to
 > describe more details about your use case.

well no, it's about 2.5ms per call to line-number-at-pos, which is 
called at least 6 times per character insertion (with my Emacs config, 
at least). Which already makes for 15ms per character insertion, 
excluding anything else done by cc-mode or lsp-mode.

 >> Since the time taken by line-number-at-pos seems to fluctuate wildly for
 >> (to me) unknown reasons, I'll try and see if I can set up a systematic
 >> way to collect reliable data.
 >
 > Yes, please do.  I'm guessing there's some factor here that is
 > important to consider.

I wrote a simple-minded measurement routine that can at least report the 
time taken between successive character insertions, and I noticed that 
better alternatives have been brought up in response to my other mailing 
list thread (titled "Latency profiling?"). I haven't had time to prepare 
a systematic test case yet, but I will look into it when I get home from 
work this evening.


- command-execute                                                5676  73%
  - call-interactively                                            5676  73%
   - funcall-interactively                                        5676  73%
    - self-insert-command                                         5080  66%
     - lsp-on-change                                              2144  27%
      - lsp--text-document-content-change-event                   1964  25%
       - lsp--point-to-position                                   1964  25%
          line-number-at-pos                                      1964  25%
      + json-encode                                                164   2%
      + file-truename                                               16   0%
     - c-after-change                                             1784  23%
      - mapc                                                      1772  23%
       + #<compiled 0x1a24bed>                                    1772  23%
      - c-invalidate-sws-region-after                               12   0%
       - c-invalidate-sws-region-after-ins                          12   0%
        - c-beginning-of-macro                                       8   0%
           back-to-indentation                                       4   0%
        - c-literal-limits                                           4   0%
           c-state-full-pp-to-literal                                4   0%
     - lsp-before-change                                          1016  13%
      - lsp--point-to-position                                    1016  13%
         line-number-at-pos                                       1016  13%
     - sp--post-self-insert-hook-handler                            56   0%
      - sp-insert-pair                                              28   0%
       - sp--pair-to-insert                                         24   0%
        - sp--all-pairs-to-insert                                   20   0%
         - sp--looking-back-p                                        8   0%
            sp--looking-back                                         8   0%
         + sp--do-action-p                                           8   0%
       + sp--get-closing-regexp                                      4   0%
      + sp--all-pairs-to-insert                                     16   0%
      + sp-escape-open-delimiter                                    12   0%
     + c-before-change                                              28   0%
     - jit-lock-after-change                                         4   0%
      + run-hook-with-args                                           4   0%
    + counsel-M-x                                                  360   4%
    + evil-open-below                                              232   3%
- lsp-ui-doc--make-request                                        643   8%
    line-number-at-pos                                             627   8%
  + file-truename                                                    8   0%
    url-hexify-string                                                4   0%
- lsp-ui-sideline                                                 528   6%
    line-number-at-pos                                             528   6%
+ timer-event-handler                                             327   4%
+ evil-escape-pre-command-hook                                    220   2%
+ #<compiled 0xb54291>                                            141   1%
+ redisplay_internal (C function)                                  88   1%
+ ...                                                              29   0%
+ yas--post-command-handler                                        20   0%
+ global-spacemacs-whitespace-cleanup-mode-check-buffers            4   0%
+ internal-timer-start-idle                                         4   0%
+ flycheck-display-error-at-point-soon                              4   0%
   flycheck-error-list-update-source                                 4   0%