performance issue - swap

[Tammy Liang]

User complain system slow, I run glance and see
the Deactivation Rate is high more than 1. I
also see several times the swap out per second is greater than 0. How can I fix the swap out and Deactivation issues to improve performance?

Thanks for any help.

[Pete Randall]

Two things I can think of:

More memory

- or -

Fewer users



Pete

[Tammy Liang]

How about kernel parameters?
Can I change kernel parameters?

[Kevin Wright]

umm.. add more memory.

what is your buffer cache set to? You can see this from glance as well. If it is high, over 1G, or even over 500MB, it is too high. You can reduce the amount of memory used for the BC by reducing dbc_max_pct.

[Steven E. Protter]

For further analyais:

post kmunte output.

swapinfo -tam

I totally agree with the memory argument assuming the swap is set up to a correct level.

SEP

[Tammy Liang]

The buffer cache is 48.0mb.

# dmesg | grep -i phys
physical page size = 4096 bytes, logical page size = 4096 bytes
Physical: 1179648 Kbytes, lockable: 820340 Kbytes, available: 950968 Kbytes
# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 2304 1046 1258 45% 0 - 1 /dev/vg00/lvol2
reserve - 609 -609
memory 802 213 589 27%
total 3106 1868 1238 60% - 0 -

Below is part of dmesg:
Swap device table: (start & size given in 512-byte blocks)
entry 0 - major is 64, minor is 0x2; start = 0, size = 4718592
Dump device table: (start & size given in 1-Kbyte blocks)
entry 0000000000000000 - major is 31, minor is 0x1f000; start = 133984,
size = 2359296

[Steven E. Protter]

Your figures confirm that more memory is needed.

Kernel tuning would help.

See this document:
http://www2.itrc.hp.com/service/cki/search.do?category=c0&docType=Security&docType=Patch&docType=EngineerNotes&docType=BugReports&docType=Hardware&docType=ReferenceMaterials&docType=ThirdParty&searchString=UPERFKBAN00000726&search.y=8&search.x=28&mode=id&admit=-1335382922+1068492235826+28353475&searchCrit=allwords
Tuning
Document id: UPERFKBAN00000726

SEP

[A. Clay Stephenson]

You are rearranging the deck chairs on the Titanic. Your only real options here are more memory or fewer processes or live with it. You could improve things slighty by having more swap devices set at equal priority but that will not make much of a difference.

[doug mielke]

There is not much memeory used for cache, reducing that is an option, but little gain possible.

Rebooting often if possible will free up some amount of memory, possibly for a very short lived gain, but in the event of sloppy software ( mem leak), could be a significant gain.

If leaky software, it's possible that no amount of memory addition is a proper long term solution. Use glance or ps -elf to determine processes memory usage, and make comparisons over a couple of days to find a possible culprit.

Otherwise, as has been said, it's more memory, or lighten load

[Mike Stroyan]

A. Clay Stephenson wrote-
"You are rearranging the deck chairs on the Titanic."

She actually seems to be rearranging the deck
chairs on one of the lifeboats. It isn't
sinking. But there just isn't enough room to
set up all of the chairs at once.

Get a bigger boat.