bug#26990: 25.2; Text refresh delay upon moving text or scrolling

bug#26990: 25.2; Text refresh delay upon moving text or scrolling

[Chris Seifried]

I'm having a strange issue where upon scrolling or shifting text up or
down with ENTER/BACKSPACE/C-k, lines of text that are supposed to be
shifted will appear to stay there for a second or two. While this
artifacting/delay is happening, any keyboard input seems to "refresh"
the buffer and the text returns to normal. This happens with
'emacs -q' as well but it seems less noticeable than running Emacs
normally. Note that I'm running X.org and Compton. This issue does not
occur with 'emacs-nox'.

System:
- x86-64 Arch-Linux on linux-lts kernel, latest updates
- Lenovo ThinkPad T550, Intel Core i7 vPro, 16 GB RAM
- X.org, Compton, GTK+ 3.22.10

Steps to reproduce:
1. Open any file with text using C-x C-f, or make a new file and type
some text
2. Place cursor somewhere before a line of text, hit ENTER (once or 
repeatedly)
3. OR for a larger file, scroll up or down slightly with the mousewheel

---

In GNU Emacs 25.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.22.10)
of 2017-04-22 built on juergen
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
Configured using:
'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
--localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules
'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe
-fstack-protector-strong' CPPFLAGS=-D_FORTIFY_SOURCE=2
LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES

Important settings:
value of $LANG: en_US.utf8
locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
text-scale-mode: t
tooltip-mode: t
global-eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit
Use +,-,0 for further adjustment [6 times]
Auto-saving...done

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message idna dired format-spec rfc822
mml mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns help-mode easymenu
cl-loaddefs pcase cl-lib mail-prsvr mail-utils face-remap time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel x-win term/common-win x-dnd tool-bar dnd fontset
image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow timer select scroll-bar
mouse jit-lock font-lock syntax facemenu font-core frame cl-generic cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese charscript case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer cl-preloaded nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote dbusbind inotify dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 90735 7305)
(symbols 48 19831 0)
(miscs 40 99 171)
(strings 32 14598 4436)
(string-bytes 1 415381)
(vectors 16 11823)
(vector-slots 8 432226 8146)
(floats 8 170 415)
(intervals 56 497 62)
(buffers 976 21))

bug#26990: 25.2; Text refresh delay upon moving text or scrolling

[Eli Zaretskii]

> From: Chris Seifried <seifried.chris@gmail.com>
> Date: Thu, 18 May 2017 23:00:53 -0400
> 
> I'm having a strange issue where upon scrolling or shifting text up or
> down with ENTER/BACKSPACE/C-k, lines of text that are supposed to be
> shifted will appear to stay there for a second or two. While this
> artifacting/delay is happening, any keyboard input seems to "refresh"
> the buffer and the text returns to normal. This happens with
> 'emacs -q' as well but it seems less noticeable than running Emacs
> normally. Note that I'm running X.org and Compton. This issue does not
> occur with 'emacs-nox'.
> 
> System:
> - x86-64 Arch-Linux on linux-lts kernel, latest updates
> - Lenovo ThinkPad T550, Intel Core i7 vPro, 16 GB RAM
> - X.org, Compton, GTK+ 3.22.10

Thanks.

Does someone else here use Compton?

Chris, is it possible for you to try without Compton?

bug#26990: 25.2; Text refresh delay upon moving text or scrolling

[Eli Zaretskii]

> From: Chris Seifried <seifried.chris@gmail.com>
> Date: Fri, 19 May 2017 10:11:25 -0400
> 
> I think I found a solution, not Emacs related. I changed the default Intel graphics acceleration method from
> SNA to UXA as described in this ArchWiki page: 
> https://wiki.archlinux.org/index.php/Intel_graphics#SNA_issues
> 
> The problem has went away completely. I originally thought this would be Emacs related because this
> behavior happened only in Emacs. Sorry for the trouble!

No sweat.  Thanks for telling us.  I'm therefore closing the bug
report.