From: "Clément Pit--Claudel" <clement.pitclaudel@live.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 21028@debbugs.gnu.org
Subject: bug#21028: Performance regression in revision af1a69f4d17a482c359d98c00ef86fac835b5fac (Apr 2014).
Date: Fri, 10 Jul 2015 09:55:18 -0700 [thread overview]
Message-ID: <559FF8F6.2060209@live.com> (raw)
In-Reply-To: <83egkgb2wo.fsf@gnu.org>
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On 07/10/2015 05:41 AM, Eli Zaretskii wrote:
>> Date: Fri, 10 Jul 2015 03:34:23 -0700
>> From: Clément Pit--Claudel <clement.pitclaudel@live.com>
>>
>> I tried to pinpoint the commit that introduced the bug, and found revision af1a69f4d17a482c359d98c00ef86fac835b5fac by bisecting between 24.3 and master. Here's the commit in question:
>>
>> af1a69f4d17a482c359d98c00ef86fac835b5fac is the first bad commit
>> commit af1a69f4d17a482c359d98c00ef86fac835b5fac
>> Author: Dmitry Antipov <dmantipov@yandex.ru>
>> Date: Wed Apr 2 17:24:19 2014 +0400
>>
>> * font.c (font_list_entities): Do not add empty vector to font cache.
>> (font_matching_entity): Likewise. If matching entity is found, insert
>> 1-item vector with this entity instead of entity itself (Bug#17125).
>
> Maybe I'm blind, but I don't see anything in that changeset that could
> explain a performance hit. The modified code seems to do
> approximately the same amount of work, and create the same data
> structures, as the original one. Are you sure that backing out those
> changes fixes your problem?
Thanks for looking into this. Yes, reverting these changes on master fixes the problem. I ran a number of experiments:
* I timed the sample code that I sent, before and after af1a69f4d17a482c359d98c00ef86fac835b5fac:
** On af1a69f4d17a482c359d98c00ef86fac835b5fac (the commit that I identified as bad):
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (redisplay t) (kill-emacs))"
real 0m2.249s
user 0m1.259s
sys 0m0.100s
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (dotimes (_ 50) (insert \"日本国\n\")) (redisplay t) (kill-emacs))"
real 0m5.749s
user 0m2.717s
sys 0m0.857s
** On 200c532bd04a67a89db602462d74706051c61178 (the previous commit)
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (redisplay t) (kill-emacs))"
real 0m2.214s
user 0m1.247s
sys 0m0.077s
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (dotimes (_ 50) (insert \"日本国\n\")) (redisplay t) (kill-emacs))"
real 0m2.226s
user 0m1.222s
sys 0m0.106s
Thus the operation of inserting these 50 lines takes about 3.5 seconds on the bad commit, while it's instantaneous in the previous commit.
* On master, timed the same code before and after reverting af1a69f4d17a482c359d98c00ef86fac835b5fac:
** Before reverting
$ time emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (redisplay t) (kill-emacs))"
real 0m2.441s
user 0m1.363s
sys 0m0.142s
$ time emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (dotimes (_ 50) (insert \"日本国\n\")) (redisplay t) (kill-emacs))"
real 0m5.149s
user 0m2.569s
sys 0m0.742s
** After reverting
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (redisplay t) (kill-emacs))"
real 0m2.413s
user 0m1.351s
sys 0m0.147s
$ time src/emacs -Q --eval "(progn (dotimes (_ 3) (set-fontset-font t 'unicode (font-spec :name \"Arial\") nil 'append)) (dotimes (_ 50) (insert \"日本国\n\")) (redisplay t) (kill-emacs))"
real 0m2.570s
user 0m1.608s
sys 0m0.083s
The figures are very similar to the tests above: with that patch inserting 50 lines takes 3 seconds, and without it it's instantaneous. Thus I think it's safe to say that this particular patch is indeed responsible for the performance regression. But maybe I'm missing something?
Cheers,
Clément.
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next prev parent reply other threads:[~2015-07-10 16:55 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-10 10:34 bug#21028: Performance regression in revision af1a69f4d17a482c359d98c00ef86fac835b5fac (Apr 2014) Clément Pit--Claudel
2015-07-10 12:30 ` Eli Zaretskii
2015-07-10 16:02 ` Clément Pit--Claudel
2015-07-10 12:41 ` Eli Zaretskii
2015-07-10 16:55 ` Clément Pit--Claudel [this message]
2015-07-15 12:32 ` Dmitry Antipov
2015-07-18 10:24 ` Clément Pit--Claudel
2015-07-18 11:16 ` Clément Pit--Claudel
2015-07-18 11:26 ` Eli Zaretskii
2015-07-18 20:08 ` Clément Pit--Claudel
2016-03-03 6:12 ` Clément Pit--Claudel
2016-03-03 6:42 ` Clément Pit--Claudel
2016-03-03 7:08 ` Clément Pit--Claudel
2016-03-03 7:33 ` Clément Pit--Claudel
2016-03-03 17:10 ` Glenn Morris
2016-03-03 17:28 ` Clément Pit--Claudel
2016-03-03 20:27 ` Eli Zaretskii
2016-07-20 21:26 ` Clément Pit--Claudel
2016-07-21 14:21 ` Eli Zaretskii
2016-07-21 14:33 ` Clément Pit--Claudel
2016-07-23 20:50 ` Clément Pit--Claudel
2016-10-04 22:17 ` Clément Pit--Claudel
2016-10-26 17:15 ` Clément Pit--Claudel
2016-10-27 14:38 ` Eli Zaretskii
2016-10-27 15:29 ` Clément Pit--Claudel
2016-10-27 15:55 ` Eli Zaretskii
2016-10-28 14:23 ` Clément Pit--Claudel
2016-10-28 14:33 ` Eli Zaretskii
2016-11-18 8:55 ` Eli Zaretskii
2016-12-18 17:33 ` Clément Pit--Claudel
2016-12-18 17:37 ` Eli Zaretskii
2016-12-18 18:04 ` Clément Pit--Claudel
2016-12-18 19:52 ` Eli Zaretskii
2016-12-18 20:44 ` Clément Pit--Claudel
2016-12-19 15:50 ` Eli Zaretskii
2016-12-19 16:25 ` Clément Pit--Claudel
2016-12-19 16:39 ` Eli Zaretskii
2016-12-19 16:55 ` Clément Pit--Claudel
2016-12-19 16:58 ` Eli Zaretskii
2016-12-19 17:13 ` Clément Pit--Claudel
2016-12-22 16:25 ` Eli Zaretskii
2016-12-22 16:49 ` Clément Pit--Claudel
2016-12-22 18:04 ` Eli Zaretskii
2016-12-22 19:08 ` Clément Pit--Claudel
2017-02-10 4:45 ` Clément Pit--Claudel
2017-03-12 11:38 ` Clément Pit--Claudel
2017-03-12 15:49 ` Eli Zaretskii
2017-03-12 17:24 ` Clément Pit--Claudel
2017-03-12 17:48 ` Eli Zaretskii
2017-03-12 19:19 ` Clément Pit--Claudel
2017-03-13 15:46 ` Eli Zaretskii
2017-03-13 16:36 ` Clément Pit--Claudel
2017-03-13 17:22 ` Eli Zaretskii
2017-03-13 19:04 ` Clément Pit--Claudel
2017-03-13 20:53 ` Eli Zaretskii
2017-03-14 19:45 ` Clément Pit--Claudel
2017-03-15 15:37 ` Eli Zaretskii
2017-03-14 15:45 ` Eli Zaretskii
2017-03-14 19:35 ` Clément Pit--Claudel
2017-03-15 15:36 ` Eli Zaretskii
2017-03-15 20:46 ` Clément Pit--Claudel
2017-03-16 15:27 ` Eli Zaretskii
2017-03-16 21:23 ` Clément Pit--Claudel
2017-03-17 8:15 ` Eli Zaretskii
2017-04-16 7:48 ` Eli Zaretskii
2017-04-16 15:28 ` Clément Pit--Claudel
2016-12-19 17:00 ` Clément Pit--Claudel
2015-07-10 15:42 ` Glenn Morris
2016-03-03 6:37 ` Clément Pit--Claudel
2016-10-04 18:56 ` Jason Gross
2017-03-13 15:54 ` bug#21028: Slow font rendering in emacs Ralf Jung
2017-03-13 17:05 ` Eli Zaretskii
2017-03-13 18:12 ` Ralf Jung
2017-03-13 20:39 ` Eli Zaretskii
2017-03-14 15:57 ` Ralf Jung
2017-03-14 17:11 ` Eli Zaretskii
2017-03-14 18:50 ` Ralf Jung
2017-03-14 19:16 ` Eli Zaretskii
2017-03-14 19:17 ` Ralf Jung
2017-03-14 20:49 ` John Mastro
2017-03-15 15:40 ` Eli Zaretskii
2017-03-14 15:47 ` Eli Zaretskii
2017-03-14 18:41 ` Ralf Jung
2017-03-14 19:16 ` Eli Zaretskii
2017-03-14 19:39 ` Ralf Jung
2017-03-14 19:45 ` Ralf Jung
2017-03-15 15:36 ` Eli Zaretskii
2017-04-22 8:54 ` Ralf Jung
2017-04-22 13:40 ` Eli Zaretskii
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