lyx 1.5 scrolling unacceptably slow

[Christian Vogler]

Gutsy x86-64 on as of August 1, 2007. T7500, Nvidia GeForce 8600M GT, driver version 100.14.11, Lyx 1.5.

With the changeover to Lyx 1.5, scrolling has become unbearably slow. To reproduce, start lyx, open Help/Tutorial, and use the scroll wheel or page up/down keys to scroll. There is a lag of several hundred milliseconds with 100% CPU usage before the window scrolls.

[Frank (frank-schaeffer)]

Cannot confirm to. On Gutsy x86-64, Mobility Radeon X1400, fglrx (8.39.4) with Lyx 1.5 scrolling down in several documents went smooth. Will test it with my GeForce 6800 GT later, also on 64bit.

But, developers please update Lyx to 1.5.1 due to several critical bugs in 1.5 (data lost and further minor things). See www.lyx.org

Best regards

Frank

[Christian Vogler (christian-vogler)]

This is odd. Please test on your Nvidia card and report back when you get a chance.

I currently use a self-compiled version of LyX 1.4, and scrolling is fast there. I will try to compile LyX 1.5 myself and see what happens.

[Christian Vogler (christian-vogler)]

Update: The same thing happens with self-compiled lyx 1.5.1. With the same text area size, scrolling through the tutorial takes 8 seconds on Lyx 1.4.5.1, and 27 seconds on Lyx 1.5.1.

[Frank (frank-schaeffer)]

I've tested for this issue on my productive machine on Feisty (32bit) with the latest Nvidia driver and Compiz Fusion enabled as well as disabled. Lyx was a binary package version 1.5.1 directly downloaded from www.lyx.org.

Scrolling is also fast here. I hope this helps to narrow the problem down.

Sorry, I cannot accomplish testing on Gutsy 64bit with Nvidia at this time, because I need a productive machine for work.

Frank

[Vincenzo Ciancia (vincenzo-ml)]

Christian: the version you self-compiled should have by default assertions turned off. Can you check that in ./configure, so we are sure assertions do not have anything to do with that?

[Vincenzo Ciancia (vincenzo-ml)]

if you have i386 you can try to manually install the two packages listed here:

http://www.di.unipi.it/~ciancia/content/deb/

these are compiled without assertions, and run evidently faster on my machine.

[Christian Vogler (christian-vogler)]

I use x86-64, so I cannot test your version. I checked src/config/.h, and the ENABLE_ASSERTIONS macro is undef'ed. So it seems that these are not to blame. I will run a full compile, just in case, sometime later when I have the time.

[Ergosys (ergosys)]

I'm also seeing this problem on 7.10, with all recent updates. I'm using a 32 bit machine, but with a Nvidia geforce 5500 fx. Xorg uses over 90% in top when scrolling (I don't know if this fact is significant, but it is usually around 50% for other apps). The scrolling problem occurs on the 1.5.0 lyx from distribution, and also 1.5.1 compiled from source.

I'm using the default nvidia driver which is installed with "Restricted Devices Manager".

[Vincenzo Ciancia (vincenzo-ml)]

I have found the following upstream bugs, that seem related. In the reports some fix is suggested (e.g. _enabling_ math preview, or cutting and pasting text if the problem is in second window opened), does some of these workarounds solve your problem? In a comment in the second report there is also a patch for testing, and a link to a binary release with the patch.

http://bugzilla.lyx.org/show_bug.cgi?id=4045
http://bugzilla.lyx.org/show_bug.cgi?id=3920
http://bugzilla.lyx.org/show_bug.cgi?id=4183
http://bugzilla.lyx.org/show_bug.cgi?id=4054

[Christian Vogler (christian-vogler)]

If I select some text in Lyx, hit Ctrl-C, and then mash the keyboard, it does become a tad faster - scrolling through the tutorial with PgDown takes 17 seconds instead of 22 in the latest Gutsy-installed version. However, Lyx 1.4 still runs circles around it, taking just 7.5 seconds.

In the second bug report there is a link to a discussion on the Lyx mailing list about how DRI implementations can dramatically affect the speed of Qt 4. I wonder whether this might not be the issue here. I have seen some weird behavior from the Nvidia 100.xx.xx series in other contexts. Unfortunately, I cannot downgrade to test this out, because earlier versions do not even support my video card.

[Frank (frank-schaeffer)]

Well, now I've been testing lyx from the repository on Gutsy AMD64 with Nvidia 6600 and nvidia-glx-new as well as nvidia-glx. I can confirm this annoying behaviour. Scrolling is unacceptable slow. So it seems to be an nvidia related issue because on my Thinkpad with ati x1400 and fglrx 8.37 lyx works very well and fast.

This occour on both compiz enabled and disabled, respectively.
Whether the workarounds described in Bug 136632 nor this ones described here works for me. I will test lyx 1.5.2 later.

Setting to confirmed and assigned to the package maintainer MOTU Developers

Please give me any advice howto trace this behaviour.

Frank

[Christian Vogler (christian-vogler)]

I recently ran into similar issues with other qt4 applications, such as the Qt4 help assistant, and the Qt4 designer.

For testing purposes, I tried switching back to the vesa Xorg driver, and now scrolling has become smooth as butter in the aforementioned applications on a GeForce 8600M GT. So, this issue is definitely related to the proprietary Nvidia drivers. Unfortunately, I need hardware accelerated OpenGL, or I would just switch to the Vesa drivers permanently.

The question now is whether it is something that can be fixed in Qt or only in the NVidia drivers.

[Christian Vogler (christian-vogler)]

It seems that this is a well-known Xrender performance problem with a lot of NVidia cards. See, for example:

http://www.nvnews.net/vbulletin/showthread.php?s=e7b3197c7aba6e25affbecdf8437d470&t=87865&page=14

Based on this, I tried installing and switching to Xgl, which made scrolling and rendering blazingly fast.

Unfortunately Xgl + Nvidia comes with its own set of problems, such as drastically reduced OpenGL performance, so it is not an ideal solution (yet).