Package: emacs;
Reported by: Akib Azmain Turja <akib <at> disroot.org>
Date: Sun, 27 Nov 2022 20:02:01 UTC
Severity: wishlist
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From: Akib Azmain Turja <akib <at> disroot.org> To: Eli Zaretskii <eliz <at> gnu.org> Cc: 59641 <at> debbugs.gnu.org Subject: bug#59641: term is very slow Date: Sat, 17 Dec 2022 18:32:09 +0600
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I missed this again! There is definitely something wrong. Anyway...
Eli Zaretskii <eliz <at> gnu.org> writes:
>> From: Akib Azmain Turja <akib <at> disroot.org>
>> Cc: 59641 <at> debbugs.gnu.org
>> Date: Sat, 17 Dec 2022 00:29:02 +0600
>>
>> >> Here are the reports (attached), but don't seem to be human readable:
>> >
>> > Copy them from the display shown by profiler-report, after you expand it
>> > completely.
>> >
>> > And the "cpu" profile is enough; the "mem" one doesn't add anything useful.
>>
>> Sorry, I missed this reply. I found this in debbugs.gnu.org. :O
>>
>> Here is the data: (I didn't redo the steps, I just did
>> 'M-x profiler-find-profile RET path/to/profile'. ;) )
>>
>> --8<---------------cut here---------------start------------->8---
>> 9397 95% - term-emulate-terminal
>> 2710 27% - term-handle-ansi-escape
>> 1831 18% - term-down
>> 8 0% term-move-columns
>> 765 7% - term-goto
>
> Doesn't surprise me: most of the time is spent in term.el's business
> logic, not in Emacs display primitives.
I know that very well.
>
> If you want to work on speeding up term.el, I suggest to start by
> loading term.el (not term.elc) manually, and repeating the profiling
> session. That could tell you in more detail where are the hot sports
> in those functions at the top of the profile. Then some clever
> optimization ideas are needed to make it significantly faster.
>
> Thanks.
I guess the hot spot here is 'vertical-motion'. 'vertical-motion' takes
various things into account, which are unnecessary for a terminal
emulator. Eat implements its own motion functions, which make their own
assumptions (e.g. each character takes exactly one column, each line
finishes with a newline, etc). I guess this might be a reason why Eat
is faster.
Note that I'm the author of Eat, and Term is a direct competitor of Eat.
So although I want Term to be faster, I will be of course biased if I
try to improve Term. But don't get me wrong, I really want Term to do
better; competition is fun when you have tough competitors!
Here is the CPU profile data, with 'term.el' loaded:
--8<---------------cut here---------------start------------->8---
1551 87% - term-emulate-terminal
1551 87% - if
1551 87% - progn
1551 87% - save-current-buffer
1515 85% - let*
1515 85% - let
1515 85% - save-current-buffer
1515 85% - unwind-protect
1515 85% - progn
1361 76% - save-restriction
1361 76% - while
1341 75% - let
1130 63% - let*
1126 63% - cond
1126 63% - let
586 33% - funcall
108 6% - vertical-motion
100 5% - jit-lock-function
84 4% - jit-lock-fontify-now
64 3% - jit-lock--run-functions
24 1% - #<compiled -0x1546ff15e132d103>
24 1% - font-lock-fontify-region
24 1% font-lock-default-fontify-region
20 1% - #<compiled -0x1540f7d5aaa5a503>
20 1% font-lock-fontify-region
4 0% - #<compiled -0x1546e4779f110a03>
4 0% - font-lock-fontify-region
4 0% - font-lock-default-fontify-region
4 0% - font-lock-extend-region-wholelines
4 0% syntax-propertize-wholelines
4 0% #<compiled -0x15468ebfcfc1d703>
4 0% - #<compiled -0x15464f08f89a1f03>
4 0% - font-lock-fontify-region
4 0% - font-lock-default-fontify-region
4 0% #<compiled -0x7e8feab343044be>
532 30% - if
528 29% - term-down
528 29% - let
344 19% - if
304 17% - if
304 17% - progn
304 17% - setq
300 16% - -
300 16% - funcall
56 3% - vertical-motion
52 2% - jit-lock-function
48 2% - jit-lock-fontify-now
32 1% - jit-lock--run-functions
12 0% - #<compiled -0x1546ecc8334f3d03>
12 0% font-lock-fontify-region
8 0% - #<compiled -0x1546d143afc77e03>
8 0% - font-lock-fontify-region
8 0% font-lock-default-fontify-region
8 0% - #<compiled -0x1546c17e6a2d8c03>
8 0% - font-lock-fontify-region
8 0% - font-lock-default-fontify-region
8 0% font-lock-extend-region-wholelines
28 1% - progn
28 1% - term-move-columns
28 1% - term-move-to-column
28 1% let
4 0% - and
4 0% =
4 0% term-adjust-current-row-cache
184 10% - cond
176 9% - term-insert-char
172 9% - let
56 3% - put-text-property
20 1% jit-lock-after-change
4 0% syntax-ppss-flush-cache
48 2% - insert-char
20 1% jit-lock-after-change
4 0% and
203 11% - if
187 10% - progn
147 8% - let
24 1% - progn
24 1% setq
24 1% - put-text-property
8 0% jit-lock-after-change
20 1% - insert
8 0% jit-lock-after-change
4 0% - term-horizontal-column
4 0% - -
4 0% - term-current-column
4 0% - cond
4 0% setq
8 0% setq
8 0% if
16 0% setq
136 7% - if
136 7% - progn
136 7% - term-handle-deferred-scroll
136 7% - let
136 7% - if
136 7% - progn
136 7% - save-excursion
136 7% funcall
18 1% - while
18 1% - progn
18 1% - if
18 1% - progn
18 1% - let
18 1% - if
18 1% - progn
18 1% - if
18 1% not
36 2% - if
36 2% - progn
36 2% - redisplay
4 0% - redisplay_internal (C function)
4 0% - eval
4 0% if
171 9% - ...
171 9% Automatic GC
40 2% - command-execute
22 1% - byte-code
22 1% - read-extended-command
22 1% - read-extended-command-1
8 0% completing-read-default
18 1% - funcall-interactively
10 0% - minibuffer-complete
10 0% - completion-in-region
10 0% - completion--in-region
6 0% - #<compiled -0x737dfeebbd42962>
6 0% - apply
6 0% - #<compiled 0x147bf53b9756e246>
6 0% - completion--in-region-1
6 0% - completion--do-completion
6 0% - completion-try-completion
6 0% - completion--nth-completion
6 0% - completion--some
6 0% - #<compiled -0xb70f507d86b95cc>
6 0% - completion-basic-try-completion
6 0% - #<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_54>
6 0% complete-with-action
4 0% - #<compiled -0x737dfeebbd42962>
4 0% - apply
4 0% - #<compiled 0x147bf53b9756e246>
4 0% - completion--in-region-1
4 0% - completion--do-completion
4 0% - completion-try-completion
4 0% - completion--nth-completion
4 0% - completion--some
4 0% - #<compiled -0xb70f507d86b95cc>
4 0% - completion-pcm-try-completion
4 0% - completion-pcm--find-all-completions
4 0% - completion-pcm--all-completions
4 0% - #<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_54>
4 0% complete-with-action
8 0% - execute-extended-command
8 0% - command-execute
8 0% funcall-interactively
7 0% - timer-event-handler
7 0% - apply
4 0% #<compiled -0xabecf6a07658066>
3 0% - #<compiled -0xabecf6a07658066>
3 0% execute-extended-command--shorter
2 0% - redisplay_internal (C function)
2 0% - term--update-term-menu
2 0% - if
2 0% - progn
2 0% - let
2 0% - easy-menu-change
2 0% - mapcar
2 0% - #<lambda 0x1984cdb809973d69>
2 0% - vector
2 0% format
--8<---------------cut here---------------end--------------->8---
--
Akib Azmain Turja, GPG key: 70018CE5819F17A3BBA666AFE74F0EFA922AE7F5
Fediverse: akib <at> hostux.social
Codeberg: akib
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