Bug 538467

Description of problem:
The GTK-VNC widget used by virt-manager/virt-viewer, uses Cairo for rendering the pixmap to its window. When rendering, it will optionally apply a scaling factor to enlarge/shrink the VNC desktop above/below its natural size. 

Since upgrading from F11 to F12, rendering the VNC desktop pixmap with scaling factor is incredibly slow.  eg when switching virt-viewer to fullscreen mode, it
 will take 15-20 seconds to render the whole page, I can see each individual scan line being drawn very slowly, and Xorg has pegged the CPU at 100%.

After Xorg has finally finished rendering the pixmap, it'll often dump the following to its log file, which seems to suggest that its doing software rendering, rather than hardware accelerated.


[mi] EQ overflowing. The server is probably stuck in an infinite loop.

Backtrace:
0: /usr/bin/Xorg (xorg_backtrace+0x3c) [0x80e587c]
1: /usr/bin/Xorg (mieqEnqueue+0x1b7) [0x80e51a7]
2: /usr/bin/Xorg (xf86PostMotionEventP+0xd4) [0x80bf8a4]
3: /usr/lib/xorg/modules/input/evdev_drv.so (0x17e000+0x3172) [0x181172]
4: /usr/lib/xorg/modules/input/evdev_drv.so (0x17e000+0x3466) [0x181466]
5: /usr/bin/Xorg (0x8047000+0x6b1f0) [0x80b21f0]
6: /usr/bin/Xorg (0x8047000+0x11ed24) [0x8165d24]
7: (vdso) (__kernel_sigreturn+0x0) [0x536400]
8: /usr/lib/libpixman-1.so.0 (0xd02000+0x57aa) [0xd077aa]
9: /usr/lib/libpixman-1.so.0 (0xd02000+0x4119f) [0xd4319f]
10: /usr/lib/libpixman-1.so.0 (0xd02000+0x1477a) [0xd1677a]
11: /usr/lib/libpixman-1.so.0 (0xd02000+0x39d50) [0xd3bd50]
12: /usr/lib/libpixman-1.so.0 (0xd02000+0x41a7a) [0xd43a7a]
13: /usr/lib/libpixman-1.so.0 (0xd02000+0x42c9b) [0xd44c9b]
14: /usr/lib/libpixman-1.so.0 (0xd02000+0x399f4) [0xd3b9f4]
15: /usr/lib/libpixman-1.so.0 (0xd02000+0x152f4) [0xd172f4]
16: /usr/lib/libpixman-1.so.0 (0xd02000+0x3b9af) [0xd3d9af]
17: /usr/lib/libpixman-1.so.0 (0xd02000+0x152f4) [0xd172f4]
18: /usr/lib/libpixman-1.so.0 (0xd02000+0x46df4) [0xd48df4]
19: /usr/lib/libpixman-1.so.0 (0xd02000+0x152f4) [0xd172f4]
20: /usr/lib/libpixman-1.so.0 (0xd02000+0x4d5ca) [0xd4f5ca]
21: /usr/lib/libpixman-1.so.0 (0xd02000+0x152f4) [0xd172f4]
22: /usr/lib/libpixman-1.so.0 (pixman_image_composite+0x177) [0xd3c847]
23: /usr/lib/xorg/modules/libfb.so (fbComposite+0x170) [0x173d70]
24: /usr/lib/xorg/modules/libexa.so (0xefe000+0xfa5b) [0xf0da5b]
25: /usr/lib/xorg/modules/libexa.so (0xefe000+0xd11e) [0xf0b11e]
26: /usr/bin/Xorg (0x8047000+0xd4a07) [0x811ba07]
27: /usr/bin/Xorg (CompositePicture+0x290) [0x810eef0]
28: /usr/bin/Xorg (0x8047000+0xce125) [0x8115125]
29: /usr/bin/Xorg (0x8047000+0xcacb4) [0x8111cb4]
30: /usr/bin/Xorg (0x8047000+0x271f7) [0x806e1f7]
31: /usr/bin/Xorg (0x8047000+0x1b8c5) [0x80628c5]
32: /lib/libc.so.6 (__libc_start_main+0xe6) [0x239bb6]
33: /usr/bin/Xorg (0x8047000+0x1b4b1) [0x80624b1]


If I reboot and add 'nomodeset' to grub kernel command line, then scaled rendering will be done at expected, very fast, speeds on a par with F11, so it appears the problem is only present with KMS.

I do not have any /etc/Xorg/xorg.conf file, so it should be using the driver defaults for everything

Version-Release number of selected component (if applicable):
xorg-x11-drv-ati-6.13.0-0.10.20091006git457646d73.fc12.i686
xorg-x11-server-Xorg-1.7.1-7.fc12.i686
kernel 2.6.31.5-127.fc12.i686.PAE

How reproducible:
Only when booted with KMS active.

Steps to Reproduce:
1. Start a guest virtual machine with libvirt
2. Run  'virt-viewer GUESTNAME'
3. Select  menu  View -> Full Screen
  
Actual results:
Switches to fullscreen and takes 20 seconds to draw the screen

Expected results:
No noticeable delay when drawing

Additional info:
I will attach log files, etc....