Bug 48395

This is a driver bug; please attach your Xorg.log.

Hi, I will add it on Tuesday. At the moment I don't have access to my pc.

Created attachment 59715 [details]
My Xorg log.

Looks like we may have an issue in the current nvidia driver, they'll want to know about that.

Can you please record a trace of working in gvim with your bitmap font using:
$ cairo-trace --profile gvim # do stuff, then quit
And let's hope the trace is less than 3MiB so it can be attached!

Then can you compare the performance using (will need to uncompress the trace first):
$ CAIRO_TEST_TARGET=image,xlib perf/cairo-perf-trace -i6 gvim.trace

Created attachment 59737 [details]
strace output

I ran the command and resized the window two or three times so it has to rebuild the screen a few times and I toggled NERDTree. 
The other thing I will check in a bit, it seems I don't have this perf/cairo-perf-trace, I will check if the AUR package has it.

Ok, a quick comparison between your trace and the one already in the cairo-traces shows that nvidia has a similar slow-down compared to the image backend for both. As such I think they are already aware of the issue, though possibly not quite aware of how much it impacts upon gvim usability.

[perf] CAIRO_TEST_TARGET=image,xlib ./cairo-perf-trace -i6 ~/gvim.trace
[ # ]  backend                         test   min(s) median(s) stddev. count
[ # ]    image: pixman 0.24.4
[  0]    image                         gvim    0.067    0.067   0.41%    5/6
[  0]     xlib                         gvim    4.129    4.130   0.55%    5/6

This is the output I get from cairo-perf-trace. It all doesn't mean much to me, but I hope it helps.

Ouch, that's even worse than on my machine. Basically it says that the driver is about 70 times slower than the CPU in this test. No wonder you can see it redraw!

[perf] CAIRO_TEST_TARGET=image,xlib ./cairo-perf-trace -i6 ~/gvim1.trace
[ # ]  backend                         test   min(s) median(s) stddev. count
[ # ]    image: pixman 0.24.4
[  0]    image                        gvim1    0.090    0.090   0.53%    5/6
[  0]     xlib                        gvim1    9.474    9.474   0.00%    4/6

The previous one was a bit wrong, I removed the cairo package from Arch [testing] and installed cairo from AUR (cairo-xcb) to see if that comes wiht the perf-trace utility. The previous output was generating using the trace from the [testing] cairo but with cairo-xcb (aur) installed. The one above was done with a new trace that I ran for the cairo-xcb.

I hear on the grapevine that a fix is now pending for the nVidia driver. Thanks for the bug report, and do let us know if the next driver update doesn't perform well.

Hi Patrick,

Chris is quite right, and I thank him for bringing this to my attention; I fixed this on the driver side. On my system, this makes your trace go from 5.674 seconds per run to 0.297 seconds. This'll be delivered in an upcoming driver release; sorry for the inconvenience!

Thanks,
 - Pierre-Loup

Hi, no problem at all. I will check the performance after the next updates(s) and keep an eye on the release notes. 
Thank you both for looking into this,
Patrick

No change with the 295.40 driver.

Hi Patrick, Andrey,

The newly-released 302.07 driver should fix this issue, in addition to other general goodness:

http://www.nvidia.com/object/linux-display-ia32-302.07-driver.html
http://www.nvidia.com/object/linux-display-amd64-302.07-driver.html

Thanks for your patience; very sorry for the initial inconvenience.

Thanks for the update (both news and the driverwise).
I will test right away when it hits the Arch repositories :)

Tab switching in Chromium didn't seem do improve with 302.07:

http://code.google.com/p/chromium/issues/detail?id=121624

$ cairo-perf-trace chromium.18279
[ # ]  backend                         test   min(s) median(s) stddev. count
[  0]      xcb                     chromium    1.973    1.987   0.62%    6/6
[  0]     xlib                     chromium    3.840    3.870   0.35%    6/6
[ # ]    image: pixman 0.24.4
[  0]    image                     chromium    0.073    0.075   1.37%    6/6
[ # ]  image16: pixman 0.24.4
[  0]  image16                     chromium    0.089    0.090   0.51%    6/6

... sure. I think you need to file a different bug, and make sure you attach the trace so that people can reproduce the issue on their end.

Too bad it is not fixed in 295.53, only in beta.