Re: oracle cause "load" on OS level very high.

if I'm not mistaken the 'load' is the number of runnable processes ... so if it peeks to 40 it means
40 processes are runnable at that moment ... this could mean that : - someone is using parallel query (pq slaves) ? - someone wrote some stupid program that connects multiple times concurrently is a short amount of time ?

- dbwriter is using dbwriter slaves ? multiple arch slaves ?
- a process is spawning a hugh amount of threads ?
- combination of above ...
- other reason :-)

My experience is on boxes that show very high runqueues and peaks of high runqueues, PQ is being abused - parallel processing is not always faster ... one time a saw a box with a runqueue (load) of 80 to 100 ... reason was a high parallel degree clause on most tables - lowering PQ -> low runqueue -> lower overhead, context switches -> increase performance ...
My experience is, depending on number of CPUs, a runqueue/load of 2 to 3 times number of CPUs is a performance limiet...

"Dominica Leung" <dominica_l_at_yahoo.com> wrote in message news:5f8af180.0208061359.6cac32d6_at_posting.google.com...
> Hi All,
>
>
> I am wondering whether anyone seen this kind of situation
> before in Performance tuning aspect.
>
> I am (this company AA) is running oracle 8.0.6.2
> 32 bits on
> solaris 2.6 OS.
>
> There is very strange thing happen.
> When I do a "top",
> everyday at 2:30 pm and 2:45PM
> (there are some cronjob from Engr dept doing select and
> update)
> the "load" from the "top" command, will be 40.00.
> This is very high, normal machine is 4 or 5.
>
> =========================================
>
> last pid: 8806; load averages: 40.00, 8.57, 9.67
> 14:50:39
> 928 processes: 923 sleeping, 2 running, 3 on cpu
> CPU states: 32.9% idle, 54.0% user, 13.0% kernel, 0.0% iowait, 0.0%
> swap
> Memory: 4096M real, 133M free, 282M swap in use, 1254M swap free
>
> =================================================
> It only spike up for 3 or 4 minutes.
>
> When I do top, I only see the
> PID is 25923, which is
> the oracle 25923 1 0 Jun 29 ? 1031:47 ora_dbw0_USRDEV
>
> My question is ?
> 1) is there anything I should look??
> I have looked at V$lock, v$transaction at that time,
> there is NO PROCESS waiting for transaction, only 14 locks in the
> whole system.
>
> Curious how to improve it, look like database writer is very busy.
>
>
> I know people might told me "this machine is MAX out" in the
> capacity. But I hope there is something I could do about it.
>
>
> Thanks,
>
>
> Dominica
Received on Wed Aug 07 2002 - 13:40:00 CDT