kernel 2.6 very sluggish
Sean Estabrooks
seanlkml at rogers.com
Tue Dec 23 10:59:41 UTC 2003
On Mon, 22 Dec 2003 16:15:45 -0800
"Calderon, Jay" <jcaldero at asante.com> wrote:
> 16:07:40 up 13 min, 2 users, load average: 3.49, 1.88, 1.04
> 59 processes: 58 sleeping, 1 running, 0 zombie, 0 stopped
> CPU states: cpu user nice system irq softirq iowait idle
> total 5.1% 0.0% 2.8% 1.2% 0.0% 90.8% 0.0%
> Mem: 124768k av, 120452k used, 4316k free, 0k shrd, 2992k buff
> 34340k active, 5724k inactive
> Swap: 262072k av, 82868k used, 179204k free 11532k cached
>
> PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEMTIME CPU CMD
> 1174 root 5 0 88292 2820 74040 S 3.0 2.2 :15 0 X
> 1816 jcaldero 15 0 24380 3992 19300 S 2.5 3.1 0:04 0 gnome-terminal
> 1863 jcaldero 17 0 5060 604 3948 R 0.4 0.4 0:02 0 top
Jay,
Your system looks to be low on memory and is swapping. Not sure what
the relevant difference is in comparison to 2.4. A "top" of a similar
workload under 2.4 would be instructive. If you press capital letter
'M' when in top you'll see a list of processes sorted by memory usage
which might help find a culprit.
Capturing the output of a "vmstat 1" command while observing slow
response in one of your applications would prove if swapping is the issue
for sure. Looking through "dmesg" output you may see some relevant
information. As well,"slabtop" will show you some of the memory
demands of the kernel itself.
Finally, you could play with setting the value of /proc/sys/vm/swappiness.
It's 60 by default and basically controls whether the kernel prefers
memory usage by application or cache data. In your situation i would
guess that lowering this value might help. However, i've heard conflicting
results so i'd suggest playing around with different settings (0-100). An
interesting first try would be:
echo 10 > /proc/sys/vm/swappiness
Incidentally, you're not the first person to report problems with 2.6
using <= 128Mb of RAM. Unfortunately, nothing may help as much as another
stick of RAM.
Good luck,
Sean
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