intermittant slow graphics, high CPU usage problem

[dcljr]

OK, I've tried to solve this by searching the forums, but no one seems to have the exact same problem I do, AFAICT, so I can't figure out what will fix this for me.

Quick background on my system (details later): running almost entirely latest stable versions on Gnome desktop with gentoo-sources-2.6.25-r9. Mostly default setup for everything, as I still don't know enough about Linux to do much tweaking. Been running this particular installation of Gentoo for 2.5 years, and a different install for 6 months before that (didn't feel like I got it right the first time).

First, the symptoms:

Everything seems fine when I first boot up and log in. Then after some apparently random amount of time (anywhere from mere minutes to several hours, although somtimes I log off without it ever happening), apparently regardless of what I've been running (Firefox, Thunderbird, Gnumeric... even just a Gnome Terminal), and for no apparent reason, certain "graphics intensive" things get really slow and CPU usage "goes to 11" (i.e., goes to 100%) for all of the following:

1. The video portions of streaming videos in Firefox (Adobe Flash plugin) get very "stuttery" (i.e., 1–2 seconds, or more, between frame updates — or the video freezes completely), while audio is much less affected (but not completely unaffected, since CPU usage goes through the roof).
   
2. Scrolling in any desktop application (as varied as those mentioned above) is slow and stuttery. This includes scrolling with the mouse wheel, clicking and dragging window scroll bars, and scrolling with up/down-arrow keys or page-up/down keys.
   
3. In terminals, automatic scrolling caused by large amounts of output (say, ls -l /usr/bin or lshal -l) can be slow as well (but see interesting caveat below).
   
4. Moving and switching between windows on the desktop is slow (i.e., a distinct pause before the screen gets redrawn after an ALT-TAB, and very jerky updating when dragging a window across the desktop).
   

However, most of these things have counterparts that do not suffer the same slowdown — at least, not to the same extent:

1. Videos opened in Totem or VLC from local copies are slow coming up initially, and switching between a window and fullscreen, but do not show especially high CPU usage in the course of normal viewing (AFAICT).
   
2. Scrolling of all sorts in non-graphical terminals (i.e., on VT1–6) seems to be completely unaffected — or, if it's slowed down at all, I can't really tell. (By the way, I don't use a framebuffer, if that's important.)
   
3. The long-output scrolling issue is actually very strange: when a Gnome Terminal is first opened (while I'm having this "slowdown" problem), an ls -l /usr/bin might actually be fast, but if the command is issued repeatedly it will eventually slow down and be stuttery, and never be fast again — until I hit SHIFT-HOME, SHIFT-END to jump to the top of the buffer and back. Then the output is fast again... until it slows down after one or two more invocations, just like before. This behavior is completely reproduceable; it happens every time (only when I'm already having the problem — it doesn't actually cause it to start happening). It's almost as if it's slowing down when the scrollback buffer gets filled up, but that can't be it, because the number of invocations of the command required to cause the slowdown varies, and besides, jumping to the top and back to the bottom doesn't clear the buffer, or anything... so why would that speed it up again, if only briefly? Weird.
   

Closing a program and reopening it doesn't help at all (last item about ls -l notwithstanding). For example, reopening Firefox or Gnumeric doesn't make their scrolling problems go away. Logging off and logging back into Gnome (and thus restarting X in the process) does fix the problem, at least temporarily (it behaves just like the first time I log on after booting up, so the problem may or may not reappear during that session) — but that's not an acceptable fix when I'm watching streaming video online!

In fact, streaming video is, I believe, the context in which I first encountered the problem, and I originally thought it was a Firefox issue, since I had recently upgraded to 3.0.10 on May 9 and then downgraded back to 2.0.0.19 on May 10, then went back to 3.0.10 on May 14. (Why I did this is not worth going into.)

Other important upgrades around this time include:

• gcc from 4.1.2 to 4.3.2-r3 on Apr 11 (compiled only, didn't switch to)
  
• xorg-server from 1.3.0.0-r6 to 1.5.3-r5 on May 8 (then 1.5.3-r6 on May 22)
  
• gnome from 2.22.3 to 2.24.1 on May 9
  

This problem has been going on for so long now, I can't actually remember when it first started happening, but based on my emerge history it's possible that I first encountered the problem on May 22, because on that day I re-merged adobe-flash-10.0.22.87 for some reason that I can no longer remember. (That version was first merged on Apr 30, after the package name was changed from netscape-flash.)

Then the next day (May 23) I re-merged xf86-input-evdev and xf86-video-nv. As I recall, since I was having scrolling problems, I thought maybe it was caused by the switch to evdev "forced" upon folks by xorg-server 1.5.3-r3.

Around this time I went on vacation for a week and when I got back, decided to get "radical" in my attempts to fix the problems:

• switched to actually use gcc-4.3.2-r3 on Jun 2, following upgrade guide by recompiling libtool, then doing emerge -e system followed by emerge -e world (that way the entire world was recompiled with a gcc-4.3.2-r3 that itself was compiled with gcc-4.3.2-r3)
  

That didn't fix the problem... but then I realized I hadn't actually recompiled my kernel with the new gcc, only reinstalled the source code. So I...

• upgraded gentoo-sources from 2.6.25-r7 to 2.6.25-r9 (latest stable release of the same version so I could reuse my .config) and compiled the new kernel on Jun 11.
  

Still didn't fix the problem. So in desperation, reasoning that some programs actually care what kernel you have (or, at least what kernel options you've enabled), I unmerged the latest stable kernel sources (2.6.29-r5), which I had never used (waiting till I had time to configure a completely new kernel), so no programs could possibly be confused as to what I had, and did...

• emerge -e world again on Jun 20
  

Of course, that didn't fix the problem, either. In fact, it was becoming so annoying, I started doing a lot of stuff (as much as possible) on the console (VT1), so I didn't have to log into my desktop environment!

After I first started typing up this post about a month ago, I tried switching Gnome themes:

• changed from Glider theme to Mist theme/engine around Jul 3rd
  

Note that I had been using the Glider theme ever since I reinstalled Gentoo 2.5 years ago. I don't really like the Mist theme, but it seems to be the fastest of the ones I can chose under System » Preferences » Appearance » Theme (gnome-appearance-properties). (Read more about my experiences with themes in this other thread of mine.)

For a while, I thought that had fixed the problem, but it's only attenuated it. It still happens, just not nearly as often — maybe 1 or 2 times a week now. (That's why I've gone for another 3 weeks without posting this!)

I've also tried creating a new user and logging in as "him" so my home directory wouldn't have any old configuration files lying about. I spent a couple of hours playing around with the configuration of the mouse, Gnome Terminal, and Firefox, and didn't encounter the problem, but I wouldn't say that's conclusive, since I thought just switching themes had solved the problem. Since then, I haven't used the other user any more.

And finally, I tried...

• keywording gtk+, gtk-engines, gnome-themes, and metacity, and upgrading to the latest unstable versions of them (Jul 10)
  

...but that was a complete failure (I can't remember exactly what happened, but it wasn't pretty), so I quickly...

• went back to the stable versions (Jul 11)
  

OK, so here's the usual output (from a month ago):

# emerge --info

[audiodef]

Well, the first thing I would want to know is after what single event things slowed down. You mentioned a bunch of different things. Did you do something that used flash in Firefox and then everything else was slow? Did you play something in Totem or VLC and thereafter the CPU load went up and stayed there?

There's usually a single culprit behind anything.

I haven't had problems with xf86-video-nv, but with xf86-video-intel, some versions just do not work very well (the latest ~arch version was so wonky I masked it in favour of 2.7.1). Did you recently update the nv driver? If so, see what an older version does.
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[dcljr]

[energyman76b]

you are using nv. That means NO acceleration at all. Everything has to be done by the cpu.

Now add to that bad start gnome, which is slow, firefox, which is extremely slow and flash, which has a surprisingly high cpu load - and your desaster is complete.

Either start using a driver that has at least basic 2d acceleration or use something less slow.
_________________
Study finds stunning lack of racial, gender, and economic diversity among middle-class white males

I identify as a dirty penismensch.

[dcljr]

[dcljr]

Well, I've now switched themes again. Since August 7th I've been using the ClearlooksClassic theme from gnome-themes (which uses the clearlooks engine) with the Metacity theme Clearlooks2-Squared (found in metacity-themes).

And even though gtkperf reveals that the current setup is significantly (about 20%) slower than when I was using Mist, AFAIR I have not had the scrolling/etc.-slowdown problem since making the change.

I'm not marking this as SOLVED, however, since this is merely a workaround, not a true solution to the problem.

- dcljr

[energyman76b]

when the problems start - do you see a spike in memory/cpu load caused by X (try htop or top to check that) - and if yes, are you using composite (I don't know if you can with nv). Another thing - are you sure that no flash/nspluginwrapper is still active? I have seen it a lot of times - all browser windows are closed, but flash/wrapper are still infesting the process list, using up precious ressources.
_________________
Study finds stunning lack of racial, gender, and economic diversity among middle-class white males

I identify as a dirty penismensch.

[dcljr]

[energyman76b]

well, if mist used transparency or something like that - in my experience when effects are used X sometimes 'goes mad'.

There are two ways to deal with it. Deactivate effects (and switchting to a theme which does not use composite stuff should have a similar effect) or restart the window manager.

In my experience of course.
_________________
Study finds stunning lack of racial, gender, and economic diversity among middle-class white males

I identify as a dirty penismensch.