Negative caching

[Steve Lamb]

Hal Burgiss wrote:
> Actually I was trying to blend a little humor with a bad situation that I
> don't fully understand.

     Ah, my apologies for missing that.  :)

> I am totally open to other causes/solutions. But what is a better explanation
> of a previously happy system whose performance degrades consistently and
> severely over time? 

     Memory leaks on one or more programs.

 > There is no sign of excessive CPU usage, and no single
> program is taking excessive memory (at least as reported). It seems to have
> all the earmarks of a really wacky swap problem. If not, its doing a good
> imitation of one. 

     No single program?  But are there a group of programs which are taking up 
an excessive amount of memory?  When I had that problem it wasn't a single 
program that was causing an issue.  It was a suite of programs.  XFCE had a 
really bad memory leak somewhere in one of their supporting libs.  As a result 
each program in XFCE would leak a little memory which, en masse, turned into a 
large memory problem for the system overall.

     I'd really want to see a ps auwx of the system when it is dog slow.  Even 
better:
ps auwx | sort -r -k 5 | less | head

     And just for completeness for those who are cautious about what commands 
do, here's the output for my current system:
{grey at igbuntux:~} ps auwx | sort -r -k 5 | less | head
grey      3263 14.3 39.8 349208 100012 ?       Ssl  Jun18  81:32 
/usr/lib/firefox-3.0.10/firefox
grey      3250  0.5 16.0 198576 40264 ?        Sl   Jun18   3:19 
/usr/lib/thunderbird/thunderbird-bin
root      2492  5.3 12.9  65100 32384 tty7     Rs+  Jun18  30:20 /usr/bin/X :0 
-br -audit 0 -auth /var/lib/gdm/:0.Xauth -nolisten tcp vt7
grey      3057  0.0  0.8  55696  2140 ?        S    Jun18   0:02 xfdesktop 
--sm-client-id 22651e406-42a8-4812-94b3-e982512ea5e1 --display :0.0
grey      3066  0.0  3.0  37996  7720 ?        Sl   Jun18   0:02 
/usr/lib/xfce4/panel-plugins/xfce4-menu-plugin socket_id 29360158 name 
xfce4-menu id 1 display_name Xfce Menu size 32 screen_position 11
grey      3076  0.0  0.9  34668  2428 ?        Sl   Jun18   0:00 
/usr/lib/xfce4/panel-plugins/xfce4-mixer-plugin socket_id 29360161 name 
xfce4-mixer-plugin id 5 display_name Mixer size 32 screen_position 11
grey      3061  0.0  0.7  32348  1792 ?        S    Jun18   0:03 
update-notifier --sm-config-prefix /update-notifier-XimSrd/ --sm-client-id 
216bb282c-d06d-488d-8d92-8c3f056e2782 --screen 0
grey      3071  0.0  0.8  31492  2168 ?        Ss   Jun18   0:02 
gnome-power-manager --sm-config-prefix /gnome-power-manager-55DaXP/ 
--sm-client-id 2ef9290af-bf15-4918-9548-1ccfb8de5771 --screen 0
grey      3052  0.6  1.8  29212  4664 ?        S    Jun18   3:49 xfwm4 
--sm-client-id 2d8a5dc6e-6171-4de8-8f07-3fd6101c8cba --display :0.0
grey      3069  0.0  0.7  27728  1888 ?        Ss   Jun18   0:00 python 
/usr/share/system-config-printer/applet.py

     Basically, giving us the top 10 programs by RAM usage in descending 
order.  We might not see a huge number on any one program but if we see 
several each with a large chunk it might give us something to go on.

-- 
          Steve C. Lamb         | But who can decide what they dream
        PGP Key: 1FC01004       |      and dream I do
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