From: Eli Zaretskii <eliz@gnu.org>
To: dmantipov@yandex.ru
Cc: emacs-devel@gnu.org
Subject: Re: Long lines and bidi
Date: Fri, 08 Feb 2013 16:46:13 +0200 [thread overview]
Message-ID: <836222983u.fsf@gnu.org> (raw)
In-Reply-To: <838v6y99wk.fsf@gnu.org>
> Date: Fri, 08 Feb 2013 16:07:23 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: emacs-devel@gnu.org
>
> Profile alone is not enough. Please tell how did you "scroll",
> exactly (which commands did you use), and please also show the
> absolute times it took to perform each command.
Btw, if you are serious about finding a solution to the long-line
display misfeature (or any other too-slow redisplay situation), I
generally find it necessary to do precision timing of the suspicious
parts of code, because otherwise it is impossible to find the actual
culprits. On GNU/Linux, I use the following simple function:
double
timer_time (void)
{
struct timeval tv;
gettimeofday (&tv, NULL);
return tv.tv_usec * 0.000001 + tv.tv_sec;
}
Now, to time a particular portion of the code, do something like this:
double t1, t2;
...
t1 = timer_time ();
/* here comes the code that should be timed */
t2 = timer_time ();
if (t2 - t1 > THRESHOLD)
fprintf (stderr, "that code took %.4g sec\n", t2 - t1);
The value of THRESHOLD depends on the magnitude of the slow-down you
are working on. I generally start with 0.1 of the time it takes to
perform some redisplay operation; e.g., if it takes 5 sec to move the
cursor, start with 0.5 sec. gettimeofday has a sufficient resolution
on GNU/Linux to get you sub-millisecond accuracy, which is more than
enough for display engine measurements.
Using the above, you can quickly identify the function(s) that take
most of the time of a particular redisplay operation, then time the
parts of those functions to find the most expensive parts, and so on,
recursively, until you find the hot spots (more than 50% of the slow
operation).
next prev parent reply other threads:[~2013-02-08 14:46 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-03 22:05 bug#13623: 24.3.50; Redisplay issue with transient-mark-mode Lawrence Mitchell
2013-02-04 15:49 ` Eli Zaretskii
2013-02-04 17:20 ` Lawrence Mitchell
2013-02-04 18:10 ` Eli Zaretskii
2013-02-05 4:54 ` Dmitry Antipov
2013-02-05 12:07 ` Dmitry Antipov
2013-02-05 17:46 ` Eli Zaretskii
2013-02-05 17:45 ` Eli Zaretskii
2013-02-06 7:16 ` Dmitry Antipov
2013-02-06 14:31 ` Stefan Monnier
2013-02-06 15:14 ` Dmitry Antipov
2013-02-06 18:04 ` Eli Zaretskii
2013-02-06 18:23 ` Eli Zaretskii
2013-02-06 20:30 ` Stefan Monnier
2013-02-07 3:41 ` Eli Zaretskii
2013-02-08 13:33 ` Long lines and bidi [Was: Re: bug#13623: ...] Dmitry Antipov
2013-02-08 14:07 ` Eli Zaretskii
2013-02-08 14:46 ` Eli Zaretskii [this message]
2013-02-08 16:38 ` Long lines and bidi Dmitry Antipov
2013-02-08 16:52 ` Eli Zaretskii
2013-02-09 3:34 ` Paul Eggert
2013-02-09 8:46 ` Eli Zaretskii
2013-02-09 9:05 ` Paul Eggert
2013-02-09 9:33 ` Eli Zaretskii
2013-02-11 2:33 ` Paul Eggert
2013-02-09 10:01 ` Eli Zaretskii
2013-02-10 16:57 ` Eli Zaretskii
2013-02-11 5:43 ` Dmitry Antipov
2013-02-11 7:54 ` Dmitry Antipov
2013-02-11 16:47 ` Eli Zaretskii
2013-02-11 23:55 ` Paul Eggert
2013-02-11 16:42 ` Eli Zaretskii
2013-02-11 17:53 ` Dmitry Antipov
2013-02-11 18:10 ` Eli Zaretskii
2013-02-11 18:21 ` Dmitry Antipov
2013-02-11 17:17 ` Eli Zaretskii
2013-02-11 17:55 ` Drew Adams
2013-02-11 18:13 ` Eli Zaretskii
2013-02-08 16:21 ` Long lines and bidi [Was: Re: bug#13623: ...] Dmitry Antipov
2013-02-08 17:04 ` Eli Zaretskii
2013-02-08 15:33 ` Stefan Monnier
2013-02-08 16:05 ` Eli Zaretskii
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