From: Dmitry Antipov <dmantipov@yandex.ru>
To: Stefan Monnier <monnier@iro.umontreal.ca>,
Paul Eggert <eggert@cs.ucla.edu>
Cc: Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: Benchmarking temporary Lisp objects [Was: Re: [RFC] temporary Lisp_Strings]
Date: Mon, 08 Sep 2014 16:01:43 +0400 [thread overview]
Message-ID: <540D9AA7.5020205@yandex.ru> (raw)
In-Reply-To: <540D85E3.5090407@yandex.ru>
On 09/08/2014 02:33 PM, Dmitry Antipov wrote:
>> Basically, this risks making Elisp's semantics more murky, so it has to
>> come with a good performance story.
Here is a "real-life" example with my favorite benchmark running over xdisp.c:
(defun scroll-up-benchmark ()
(interactive)
(let ((oldgc gcs-done)
(oldtime (float-time)))
(condition-case nil (while t (scroll-up) (redisplay))
(error (message "GCs: %d Elapsed time: %f seconds"
(- gcs-done oldgc) (- (float-time) oldtime))))))
==> 401 GCs, ~29.9s.
With two-lines change:
=== modified file 'src/textprop.c'
--- src/textprop.c 2014-09-07 07:04:01 +0000
+++ src/textprop.c 2014-09-08 11:49:52 +0000
@@ -1319,7 +1319,8 @@
markers). If OBJECT is a string, START and END are 0-based indices into it. */)
(Lisp_Object start, Lisp_Object end, Lisp_Object property, Lisp_Object value, Lisp_Object object)
{
- Fadd_text_properties (start, end, list2 (property, value), object);
+ Lisp_Object val = scoped_cons (property, scoped_cons (value, Qnil));
+ Fadd_text_properties (start, end, val, object);
return Qnil;
}
it shows 399 GCs and ~29.6s.
Here we just allocate 2 cons cells (32 bytes on a 64-bit system) on stack,
and can see a measurable performance improvement. I believe that carefully
used stack allocation can give a much more visible improvement for a wide
range of Lisp workloads.
Dmitry
next prev parent reply other threads:[~2014-09-08 12:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-02 12:55 [RFC] temporary Lisp_Strings Dmitry Antipov
2014-09-02 13:21 ` Andreas Schwab
2014-09-02 13:47 ` Dmitry Antipov
2014-09-02 14:14 ` Andreas Schwab
2014-09-02 15:00 ` Eli Zaretskii
2014-09-02 14:00 ` Stefan Monnier
2014-09-02 15:13 ` Dmitry Antipov
2014-09-02 17:32 ` Stefan Monnier
2014-09-03 10:23 ` Benchmarking temporary Lisp objects [Was: Re: [RFC] temporary Lisp_Strings] Dmitry Antipov
2014-09-03 13:14 ` Stefan Monnier
2014-09-03 14:39 ` Paul Eggert
2014-09-03 15:39 ` Dmitry Antipov
2014-09-03 16:42 ` Paul Eggert
2014-09-03 17:47 ` Stefan Monnier
2014-09-03 18:00 ` Paul Eggert
2014-09-04 4:59 ` Dmitry Antipov
2014-09-04 5:13 ` Paul Eggert
2014-09-04 5:51 ` Dmitry Antipov
2014-09-04 6:45 ` Paul Eggert
2014-09-04 13:11 ` Stefan Monnier
2014-09-04 13:37 ` Dmitry Antipov
2014-09-04 14:46 ` Dmitry Antipov
2014-09-04 16:03 ` Paul Eggert
2014-09-05 4:00 ` Dmitry Antipov
2014-09-05 4:24 ` Stefan Monnier
2014-09-05 9:28 ` Dmitry Antipov
2014-09-05 7:15 ` Paul Eggert
2014-09-05 9:16 ` Dmitry Antipov
2014-09-05 14:35 ` Paul Eggert
2014-09-05 15:35 ` Stefan Monnier
2014-09-08 10:33 ` Dmitry Antipov
2014-09-08 12:01 ` Dmitry Antipov [this message]
2014-09-08 13:30 ` Stefan Monnier
2014-09-08 12:44 ` Stefan Monnier
2014-09-08 13:30 ` Stefan Monnier
2014-09-02 14:37 ` [RFC] temporary Lisp_Strings Paul Eggert
2014-09-02 15:24 ` Dmitry Antipov
2014-09-02 15:28 ` Dmitry Antipov
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