Use of SVG backdrop by default causes extremely slow gdm startup on armel

[Dave Martin]

Binary package hint: xubuntu-artwork

With no accelerated SVG implementation for ARM at present, this is causing a delay of about 1 minute between gdm startup and displaying a login box on an 800 MHz ARMv7 platform. This at least doubles the time from boot to a login prompt on this platform.

By contrast, scaling a 1680 x 1050 .png to fit the 800 x 600 screen size (as done in the previous xubuntu-artwork) gives a much faster gdm startup time (start of execution to display of login box) of about 6 seconds. I've tested this by editing /usr/share/gdm/themes/xubuntu/Xubuntu.xml to change the background image file and leave everything else the same.

Ideally, this kind of bulk SVG graphics rendering should not be on the boot+login critical path, the rendered image should be persistently cached, or there should be a way for the default backdrop to fall back to another (probaly png or jpeg) format for selected platforms such as armel.

$ lsb_release -a
Distributor ID: Ubuntu
Description: Ubuntu jaunty (development branch)
Release: 9.04
Codename: jaunty

$ apt-cache policy xubuntu-artwork
xubuntu-artwork:
  Installed: 0.24
  Candidate: 0.24
  Version table:
 *** 0.24 0
        500 http://arm-ports-ubuntu jaunty/universe Packages
        100 /var/lib/dpkg/status

[Michael Casadevall (mcasadevall)]

Milestoning to get this on the release team's tracker, and assigning it to myself.

I discussed this with Cody; the sanest solution is we'll keep the SVGs in the source package, and convert at build time to PNGs, which should resolve the slowdown on ARM.

[Dave Martin (dave-martin-arm)]

Sounds OK as a solution--- the time taken to resample a large PNG down seems much less of an issue than the time taken to render SVG.

[Launchpad Janitor (janitor)]

This bug was fixed in the package xubuntu-artwork - 0.25

---------------
xubuntu-artwork (0.25) jaunty; urgency=high

  * Modified the theme to use PNGs vs. SVGs due to speed
    issues on slower architectures, especially ARM (LP: #351588)
  * Makefile:
    - Takes the source SVGs and converts to PNGs at build time
  * gdm_svg/Makefile:
    - New file to generate pngs, and install them into the DESTDIR
  * debian/control:
    - Added build-dep on librsvg2-bin
  * debian/xubuntu-artwork.install:
    - Install the new PNGs into their proper places

 -- Michael Casadevall <email address hidden> Mon, 30 Mar 2009 10:52:21 -0400

[Dave Martin (dave-martin-arm)]

Got the update – much better now, thanks