SWAP

[Nobody's Hero]

SWAP DEVICE | AVAIL |USED | TYPE | PRIORITY
---------------------------------------------
/vg00/lvol2 | 1.7gb | 0mb | DEV | 1
/vg02/lvol1 | 3.8gb |2.2gb| DEV | 0
pseudo-swap | 2.3gb |1.4gb|memory| NA

OK here is what my swap looks like. I am running PeopleSoft(DOG/HOG) on a T600 for development. Production runs on 2 N's. So, I think I have a lack of memory resources. I keep getting an error that states that the box is exceeding swap usage allowed. ERROR = ""Available SWAP space is less than the configured threshold."" Should I change priority of my swap file or do you think that adding swap will not help, so I need more memory. Or a possible memory leak. I try never to boot this box. Uptime is 85 days, but when I reboot some swap issues go away. Memory leak???

swapinfo -tm

TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1776 0 1776 0% 0 - 1 /dev/vg00/lvol2
dev 3878 2268 1608 58% 137600 - 0 /dev/vg02/lvol1
reserve - 1574 -1574
memory 2352 1477 875 63%
total 8006 5319 2685 66% - 0 -

[Carlos Fernandez Riera]

See kernel configuration for swap_chunk_size
and max_swap_chunks.

Use Sam->kernel , help.

[Nobody's Hero]

Carlos,

swchunk = 2048
maxswapchunks = 2895

Am I way off?
Not sure how I can tune thia a little better, any ideas?

Bob

[Rainer von Bongartz · Accepted solution]

Robert,

If you suspect a memory leak you should do the following:

check the size of your processes

You can get the top virtual memory usage processes like this:
UNIX95= ps -e -o ruser,sz,vsz,pid,args | sort -rnk3 | head -3

If they stay constant you dont have a memory leak in user space.
There might still be a meory leak in the kernel.

check this with kmeminfo. If you dont't have kmeminfo download PHCO_20262. This contains kmeminfo.

Regards
Rainer

[kish_1]

Please check folowing kernel parameters and set it
dbc_min_pct 2
dbc_max_pct 5

[S.K. Chan]

While memory leak is the most probable cause, I'll just like to bring out one thing that I observed. You got 2 device swap setup (different LV size) with different priority. With both of them coming from a different VGs, this is a good thing (different disks) but in general multiple swaps on different disks perform better if they are the same size and with the same priority (pri=1). This allows interleaved swapping which means the swap areas are written to concurrently thus minimizing diskhead movement. It would be benificial to modify this behavior in your swap setup. For example split /dev/vg02/lvol1 into 2 separate LVs of 1.7GBs and later added it to swap and make 'em all priority 1. Better still if your 3rd 1.7GB swap comes from a diferent VG instead of vg02.