gdm loads slowly

(In reply to comment #0)
> I'm running Ubuntu Breezy, and has been updated today. However gdm is still
> loading slow for me, it takes ~2 seconds to load the graphic, and loads it
> diagonally and jagged -- it doesn't look very nice. Hoary on the other hand
> loads gdm instantly on the same machine.

Same here. I'm on a Dell Inspiron 510m Laptop. Here is lspci -vv for me:

0000:00:02.0 VGA compatible controller: Intel Corp. 82852/855GM Integrated
Graphics Device (rev 02) (prog-if 00 [VGA])
        Subsystem: Dell: Unknown device 0164
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR-
        Latency: 0
        Interrupt: pin A routed to IRQ 11
        Region 0: Memory at f0000000 (32-bit, prefetchable) [size=128M]
        Region 1: Memory at faf80000 (32-bit, non-prefetchable) [size=512K]
        Region 2: I/O ports at c000 [size=8]
        Capabilities: [d0] Power Management version 1
                Flags: PMEClk- DSI+ D1+ D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

0000:00:02.1 Display controller: Intel Corp. 82852/855GM Integrated Graphics
Device (rev 02)
        Subsystem: Dell: Unknown device 0164
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B-
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort-
<MAbort- >SERR- <PERR-
        Latency: 0
        Region 0: Memory at e8000000 (32-bit, prefetchable) [size=128M]
        Region 1: Memory at faf00000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: [d0] Power Management version 1
                Flags: PMEClk- DSI+ D1+ D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

I'm using the i810 driver, which was detected by the installer.

Cheers.

Thanks for your bug. 2s is not that slow to start gdm, is it? I don't notice any
slowdown for my part and I'm not convinced that a bug. Maybe that's an xorg
slowdown? Or maybe that due to GTK/cairo. Anyway probably better to discuss than
on a list than opening a bug ...

The thing is, I have a very fast system and gdm loaded as such in Hoary. I would
have thought this problem would be worse for slower machines. Not sure however.
IMHO, it's not so much the time, it's the uglyness :).

But yes, definitely not a high priority problem.

the slowness is subjective and could be due to an issue on your box, a slow
disk, cairo, xorg, the video driver you use ... not sure of how to debug that

This bug doesn't really matter. It was a mistake submit it, but I do understand
some things better now.

This is cosmetic, but genuine. It may be that there is something we can do
about it. If someone could try the test below, that could help isolate the problem.

<mdz> seb128: the gdm slowness issue is something to do with how the background
is drawn; I see it here too
<mdz> seb128: did something change from bitmap to svg or something like that?
<ogra> mdz, nothing changed in the artwork
<seb128> mdz: not that I known of
<seb128> s/known/know/
<seb128> mdz: maybe gtk/cairo ...
<ogra> seb128, what does gdm use to draw the fullscreen background ? cairo, canvas ?
<seb128> mdz: cairo has created slowdown for some stuff
<mdz> seb128: I see this everywhere, on completely different hardware, so I
don't think it's X related
<mdz> it's completely cosmetic of course, but it gives the impression of
slowness :-/
<mdz> people will say that the entire system is slower because it makes them
feel this way
<ogra> its very likely that its cairo...
<seb128> it's the kind of issue not easy to track since it's subjective
<ogra> probably svg artwork would help
<mdz> it's basically scaling a bitmap and drawing it on the screen
<mdz> should
<mdz> be very quick
<mdz> seb128: are there any simpler programs which use cairo to do this, so that
we can more easily compare and profile them?
<seb128> one stuff to try for somebody noticing the difference with hoary would
be to run gdm with GTK 2.6 and 2.8

First thing to try would be for somebody noticing the difference to build the
current package on an hoary box and try if it notices a difference. The current
package should build on an hoary system without any change.

Does anybody want to play with that? Let me know if you need instructions on how
to build the current package on hoary.

(In reply to comment #7)
> First thing to try would be for somebody noticing the difference to build the
> current package on an hoary box and try if it notices a difference. The current
> package should build on an hoary system without any change.
>
> Does anybody want to play with that? Let me know if you need instructions on how
> to build the current package on hoary.
>

Howdy. Yes, I'd like to give that a go. If you could send me instructions I
would appreciate that. The problem certainly is not subjective. Hoary displays
the gdm screen instantly. With Breezy you can see the gdm screen drawing from
top to bottom. It _very_ noticeable, and _very_ slow. This problem was posted
and discussed briefly on ubuntu-devel, but we were told to post a bug here, so
we did.
Anyway, yes, I would like to build it on a hoary box, so if you could let me
know how I will help out.

Cheers,

(In reply to comment #8)

> Howdy. Yes, I'd like to give that a go. If you could send me instructions I
> would appreciate that.
> Anyway, yes, I would like to build it on a hoary box, so if you could let me
> know how I will help out.

add deb-src http://archive.ubuntu.com/breezy main to your hoary
/etc/apt/sources.list
apt-get update
apt-get source gdm

Then you get the sourcecode for gdm

https://wiki.ubuntu.com/PbuilderHowto shows you how to set up pbuilder to build
source / .dsc file into an installable .deb package.
apt-get install pbuilder, then follow the howto.
it should build easily, if it does not, please ask for help here, or on
irc/mailing list.

you don't need to bother installing a pbuilder to build a package for you, just do:
- sudo apt-get build-dep gdm
- apt-get source -b gdm

I can confirm this.

Hoary's gdm is faster than breezy's.

AMD Athlon 1300, nv-driver.

Hello,

I added breezy main sources to my sources.list,
apt-get update
apt-get build-deps gdm
apt-get source -b gdm

The package built fine, but...
Preparing to replace gdm 2.6.0.7-0ubuntu7 (using
gdm_2.8.0.4-0ubuntu6_i386.deb) ...
Unpacking replacement gdm ...
dpkg: dependency problems prevent configuration of gdm:
 gdm depends on libpam-runtime (>= 0.76-22ubuntu3); however:
 Version of libpam-runtime on system is 0.76-22.
dpkg: error processing gdm (--install):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 gdm

So, I did a dpkg -i --force-all, which let it install, but when gdm loads it
complains about bad configuration, so it only loads the GTK+ greeter, rather
than the themed greeter, so I can't tell if it's worse or not. Using the login
screen setup util to change to the themed greeter makes no difference.

> Unpacking replacement gdm ...
> dpkg: dependency problems prevent configuration of gdm:
> gdm depends on libpam-runtime (>= 0.76-22ubuntu3); however:
> Version of libpam-runtime on system is 0.76-22.

This is due to the changes made this week. You can change debian/control to not
force the version before building the package

> So, I did a dpkg -i --force-all, which let it install, but when gdm loads it
> complains about bad configuration, so it only loads the GTK+ greeter, rather
> than the themed greeter, so I can't tell if it's worse or not. Using the login
> screen setup util to change to the themed greeter makes no difference.

maybe you can try to install the version of the package at the installation?

After sorting out the problems above, I've now got breezy gdm running on hoary.
It runs just as fast as hoary gdm, and does not exhibit the behaviour seen in
breezy.

*** Bug 21807 has been marked as a duplicate of this bug. ***

Ive installed Breezy on 3 machines so far (a Hoary install upgraded to Breezy),
and on each one it has exhibited this problem. So if it's not Breezy's gdm
causing this problem, then what else is left? Xorg? Drivers?

Also can this be changed to confirmed, since there are a number of different
people experiencing the same issue.

Does anyone *not* have this issue?

(In reply to comment #17)
> Does anyone *not* have this issue?
>

It is likely to affect everyone equally. It's just that it's essentially a
cosmetic issue, and we have much more severe bugs that need attention right now.
 If someone could spare some time to dig into the code and find out if there's
something we can do to regain some performance, that would be a great help to
the development team.

I've just noticed something interesting. It's not only when gdm loads, but also
when you console switch. For example, try sitting at the gdm screen, then
switching to console 1, then back to 8 (or whatever your gdm is on). For me, the
screen goes completely white for a second, and then gdm redraws itself just like
on startup. Maybe this is useful?

I've tracked that to an interpolation change of libgnomecanvas for GNOME 2.12.
This upload fixes the issue:

 libgnomecanvas (2.12.0-0ubuntu2) breezy; urgency=low
 .
   * debian/patches/gdmslownessfix.patch:
     - undo the upstream (GNOME: #129891) interpolation change,
       fix the gdm slowness (Ubuntu: #15373).