Bug 1400417

Summary: unwanted cache flush in Freetype engine
Product: [Fedora] Fedora Reporter: Maxim Prohorenko <maxim.prohorenko>
Component: qt5-qtbaseAssignee: Than Ngo <than>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 25CC: avolk07, jgrulich, jreznik, rdieter, than
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Target Release: ---   
Hardware: x86_64   
OS: Linux   
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Last Closed: 2017-07-26 06:49:13 UTC Type: Bug
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Patch from QT git none

Description Maxim Prohorenko 2016-12-01 07:29:30 UTC
Created attachment 1226647 [details]
Patch from QT git

Description of problem:

QT 5 font rendering very slow.

Need fix form qt:

REG: Fix unwanted cache flush in Freetype engine
6f423555eba55ccdf7287071e10576bc1b687fd2

Version-Release number of selected component (if applicable):

Fedora 25

Installed Packages
Name        : qt5
Arch        : noarch
Epoch       : 0
Version     : 5.7.0
Release     : 9.fc25
Size        : 9.0 k
Installed Packages
Name        : qt5-qtbase
Arch        : x86_64
Epoch       : 0
Version     : 5.7.0
Release     : 3.fc25
Size        : 8.3 M
Repo        : @System


How reproducible:
100% load 1 core in Glyph rendering.
If use nvidia driver - GL context freez.
If use nouveau - system too slow.

Steps to Reproduce:
0. Set text anti-aliasing Enable->Full
1. Open kwrite
2. Open qtbase-opensource-src-5.7.0/src/gui/doc/src/richtext.qdoc
3. Switch font to inconsolata
3. Scroll, slow
4. Switch font to consolas
5. Scroll, very slow!


Actual results:
QFontEngineFT::alphaMapForGlyph in top of callgrind

alphaMapFromGlyphData

Fonts very slow


Expected results:
Fast fonts, smooth scrolling.

Additional info:
Apply patch, rebuild qt5-qtbase* .rpm, speedup system.

Comment 1 Rex Dieter 2016-12-01 14:37:35 UTC
A qt-5.7.1 bugfix update that includes this fix is being worked on.

Comment 2 Than Ngo 2017-07-26 06:49:13 UTC
it's fixed in latest qt5-qtbase-5.7.1-19 which was pushed into stable f25 last week.