Negative caching

Hal Burgiss hal at
Wed Jun 17 21:42:08 UTC 2009

I think I've figured out why recent Ubuntu has such abysmal performance. Very
cleverly over a period of time, it takes all the free memory and uses it to
store useless junk that you will never ever use. And then holds on to the
useless stuff as long as it possibly can. And then you are forced to
work out of swap. If I leave my system for any length of time, like overnight,
it is unusable. The delay in simple everyday things like typing in a *text
terminal* (yes, text!), is ridiculous. Changing workspaces or opening a window is
insanely slow. Pity the poor soul that has to re-open Firefox. Maybe it takes
a week to build up that negative cache, but once its got you, you're toast.
Then its time to reboot or restart X, or lest you get that "watching paint
dry" feeling for the simplest most everyday things.

atop data:

PRC | sys   0.76s | user   1.70s | #proc    200 | #zombie    2 | #exit      ?
CPU | sys      7% | user     17% | irq       1% | idle      0% | wait     75%
CPL | avg1   2.90 | avg5    2.54 | avg15   2.23 | csw     9527 | intr    5228
MEM | tot  992.4M | free   91.3M | cache 316.9M | buff    3.2M | slab   44.1M
SWP | tot    2.9G | free    1.4G |              | vmcom   3.2G | vmlim   3.3G
PAG | scan  10364 | stall      0 |              | swin    4293 | swout    585 (red)
DSK |         sda | busy    100% | read    1625 | write    608 | avio    4 ms (red)

The quality of life of recent Ubuntu is on a par with Windows 3.1. 8.10 and
9.04 should be thrown on the scrap heaps of failed experiments. They suck out

I used to brag about never having to reboot a system to maintain usability.
Not no more. Its the new "normal". 

Being a diehard Ubuntu user (home, work and servers at work), its hard for me
say whether its Linux in general, or just Ubuntu, that totally sucks for a
desktop. But suck it is. 

End rant.


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