topic Re: system performance slow in Operating System - HP-UX

system performance slow

Nagaraju Gudala — Tue, 14 Oct 2003 04:45:21 GMT

model C3600
Phy memory 1GB
swapinfo o/p is given below .Can anything be done to improve the performance of the system
[/]#swapinfo
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1048576 308596 739980 29% 0 - 1 /dev/vg00/lvol2
dev 2048000 311156 1736844 15% 0 - 1 /dev/vg00/lvol10
reserve - 814956 -814956
memory 750232 227808 522424 30%

Re: system performance slow

curt larson_1 — Tue, 14 Oct 2003 05:02:25 GMT

hard to say from our information, but it isn't a good idea to put multiple swap areas that have the same priority on the same disk.

check to see if the physical volume is the same for lvol2 and lvol10. it is best to have them on seperate drives.

Re: system performance slow

john korterman — Tue, 14 Oct 2003 05:15:23 GMT

Hi,
you should not rely on the swapinfo command as the only source of information for determining the reason for bad performance.
Your swapinfo command reports that a portion of memory amounting up to 308596 and 311156 kb of disk space has been swapped. But swapinfo does not update dynamically; you get the max use since last reboot and absolutely no clue as to when!
Swapping should of course be avoided completely, but you should do some more investigation first, e.g. for testing the current memory use, try vmstat. Glance is also a good tool for monitoring how system resources are used.

regards,
John K.

Re: system performance slow

Mark Grant — Tue, 14 Oct 2003 05:29:36 GMT

At first glance it looks like the sytem is swapping but you can only tell from this that the system has swapped.

It might be worth doing a "vmstat -S 1" and look at the "si" and "so" columns. "iostat" is good for looking at disk io at a disk device level too.

I think we possibly need more information here.

Re: system performance slow

Kent Ostby — Tue, 14 Oct 2003 06:21:39 GMT

You may have a process that is hogging things up.

I sometimes run the following command multiple times to get a "quick and dirty" feel for what is hogging cpu:

ps -ef | cut -c42-80 | sort -nr | head

Hope this helps.

Best regards,

Kent M. Ostby

Re: system performance slow

T G Manikandan — Tue, 14 Oct 2003 06:28:05 GMT

C3600 has only one processor.Though there is usage of swap,jus check the usage of the CPU.

REvert

Re: system performance slow

Nagaraju Gudala — Wed, 15 Oct 2003 00:11:31 GMT

after running vmstat -S 1 si and so o/p is 0 0

Re: system performance slow

T G Manikandan — Wed, 15 Oct 2003 00:46:09 GMT

Also check the value of "po" in the vmstat output.

If you find that the swap usage is less and performance bottleneck is there

1.What is the value of the kernel parameters dbc_max_pct.
This defines the buffer cache of the system.This parameter is for dynamic buffer cache enabling parameter.
This is enabled once nbuf=0 and bufpages=0 which define the static buffer cache.
By default the value of dbc_max_pct is 50%.
Bring that down to 300MB ie.30% of your memory,assuming that your memory size is 1Gb.

Also,let us start from here

What is the output of
#sar -u 5 20

check for the columns of
idle%
sys%
user%
wio%

REvert with the output