Thank you again, Daniel.  I will see what I can do to gather some
data. I have already checked on pstack. Ubuntu packages a version but
only for i386; alas, I am running x86_64. I may be able to setup a
machine at work as a testbed, though.


On Sat, Jan 28, 2012 at 11:51 PM, Daniel van Vugt <email address hidden> wrote:
> Michael, I thought about it and using a debugger may be appropriate.
> Because callgrind (and valgrind in general) will slow down compiz/unity
> to an almost unusable speed. You won't want to run it that way for long
> enough to even reproduce the gradual degradation. Also, the "gradual
> degradation" will be drowned out by the constantly poor performance of
> running under valgrind/callgrind anyway.
>
> Using gdb you can use the "bt" or "where" commands to show the full call
> stack, which is useful. HOWEVER there is a lot to get right before the
> data is useful...
>
> 1. You need to choose the correct thread in the compiz process, or else
> you're looking at a useless stack. Probably thread 1, or whichever
> thread has "main ()" at the bottom.
>
> 2. You need to collect the full call stack (all functions) to be useful,
> not just one function.
>
> 3. You need many samples. A process using 20% CPU will only show you the
> offending call stack 1 in 5 attempts, on average. The rest of the time
> it will be idle and show you nothing useful. So you need many many
> samples.
>
> It seems like a lot of effort to use gdb. In a previous life I used to
> ask my users to use "pstack" (on Solaris) which is a simple command that
> did all the debugger steps you need in a single command. If you can find
> a "pstack" alternative for Linux and run it many times then that would
> be easiest, fastest, and least invasive to your system.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/888039
>
> Title:
>  Gradual degradation in desktop performance.
>
> Status in Compiz:
>  Confirmed
> Status in “compiz” package in Ubuntu:
>  Confirmed
>
> Bug description:
>  Over the span of 1-3 days I see my desktop consistently become more
>  sluggish. The functions most affected are window movement, file icon
>  movement, and sometimes window resizing. Other animations (such as
>  minimizing fades, switching desktops, expo mode) are not affected when
>  this degradation occurs. They remain smooth; however, I have let the
>  problem go on as long as to find out that eventually all desktop
>  animations/effects will degrade, it just takes a lot lot longer. I
>  find that my actual 3D gaming goes unaffected (though I have no data
>  to back that up, perhaps it does).
>
>  I have recorded the output of 'ps auxw' and have slowly watched the
>  VSZ and RSS memory columns creep upwards. A fresh compiz session will
>  see 675164 and 169860, respectively. After a day or two it will result
>  in as high as 878552 and 255664. I have attached a log output from an
>  hourly cron job (though I had suspended for a few days because of
>  travel).
>
>  After the degradation has occurred compiz will consistently use higher
>  CPU. Dragging a terminal window while watching top: before: ~10%,
>  after: ~30 percent.
>
>  This has been an issue since 11.04 for me on both my Intel i915 and
>  Nvidia (proprietary) machines (had an 8600 GT and upgraded to 560 GTX,
>  both having the same issue). However, the nvidia machine is where it
>  really hurts, _always_ happening within a day or two, while the i915
>  machine is pretty reliable overall with certain instances of
>  degradation (used to be affected just as badly in 11.04).
>
>  I will attach two videos demonstrating behavior before and after.
>  ---
>  ApportVersion: 1.23-0ubuntu4
>  Architecture: amd64
>  CheckboxSubmission: 33c9cec13de798ee31ce4ea2f2cbd4df
>  CheckboxSystem: 4ed15c40009aa6f7770f606350a390a2
>  CompizPlugins: [core,detection,composite,opengl,decor,regex,winrules,compiztoolbox,animation,grid,vpswitch,snap,place,gnomecompat,resize,move,mousepoll,imgpng,workarounds,session,expo,wall,fade,scale,unityshell]
>  DistroCodename: oneiric
>  DistroRelease: Ubuntu 11.10
>  DistroVariant: ubuntu
>  InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007)
>  NonfreeKernelModules: nvidia
>  Package: compiz 1:0.9.6+bzr20110929-0ubuntu5vv1
>  PackageArchitecture: all
>  ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
>  Tags:  oneiric running-unity oneiric running-unity ubuntu
>  Uname: Linux 3.0.0-12-generic x86_64
>  UnreportableReason: This is not a genuine Ubuntu package
>  UpgradeStatus: Upgraded to oneiric on 2011-10-13 (26 days ago)
>  UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/compiz/+bug/888039/+subscriptions