Re: The Emacs master is much slower than the emacs-27 branch.

[Stephen Berman]

On Fri, 04 Dec 2020 18:03:27 +0100 Stephen Berman <stephen.berman@gmx.net> 
wrote:

> On Fri, 04 Dec 2020 18:31:48 +0200 Eli Zaretskii <eliz@gnu.org> wrote:
>
>>> From: Stephen Berman <stephen.berman@gmx.net>
>>> Cc: acm@muc.de,  emacs-devel@gnu.org
>>> Date: Fri, 04 Dec 2020 17:03:00 +0100
>>>
>>> > Thanks.  This is very strange.  What are the build options and the
>>> > features in each build? are they identical?
>>>
>>> emacs-27:
>>>
>>> system-configuration-options
>>> "'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
>>>
>>> system-configuration-features
>>> "XPM JPEG TIFF GIF PNG RSVG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY ACL
>>> GNUTLS LIBXML2 FREETYPE HARFBUZZ XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11
>>> XDBE XIM MODULES THREADS LIBSYSTEMD PDUMPER LCMS2 GMP"
>>>
>>> master:
>>>
>>> system-configuration-options
>>> "--with-xwidgets 'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
>>>
>>> system-configuration-features
>>> "XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
>>> INOTIFY ACL GNUTLS LIBXML2 FREETYPE HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS
>>> GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LIBSYSTEMD PDUMPER LCMS2"
>>
>> Could Cairo be the factor here?  Emacs 27 was built without it.
>
> On Fri, 04 Dec 2020 11:49:25 -0500 Stefan Monnier <monnier@iro.umontreal.ca> 
> wrote:
>
>> Hmm... so in Emacs-28, "you" removed XFT and GMP and replaced them with
>> CAIRO and XWIDGETS.
>>
>> I doubt GMP and XWIDGETS make any difference, but maybe XFT or CAIRO
>> have something to do with the difference.
>>
>> It might be worth fiddling with `--with(out)-xft` and
>> `--with(out)-cairo` to see if you can get closer to the origin of
>> the difference.
>
> I can try that, but since I used the default configuration features,
> that suggests that those who got no difference between emacs-27 and
> master with the benchmark, or where emacs-27 was even faster, built
> emacs-27 --with-cairo and --without-xft.  Is that the case?

Well, I went ahead and configured emacs-27 --with-cairo --without-xft,
rebuilt and ran the benchmark, and it still took ~60 seconds.  I've
attached the profile because it is considerably longer than the other
emacs-27 profiles, though in general it seems similar to me, but maybe
an expert will spot a significant difference.

Steve Berman

profile-27-cairo
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