Re: jobs running in one subsystem take up more CPU then rest of jobs

Interactive default priority has been 20 for years. The controlling
subsystem default is 10. The controlling subsystem (usually QCTL) should
run at a higher priority than the interactive subsystem (usually QINTER) to
allow an operator the ability to terminate a runaway interactive job (among
other things). If you've left batch at 50, there's no reason for
interactive to be at 10; 20 is perfectly fine.

Anyway, the short answer to your question is that interactive jobs have
different run characteristics than batch. Batch jobs want CPU/RAM/Disk
pretty much constantly as they're doing their thing. The jobs run
continuously until finished.

Interactive jobs spend the vast majority of their time doing nothing while
waiting for the user to submit a screen (by pressing Enter, a function key,
etc.). When a screen is displayed and the user is looking at it, and even
when they're entering data on the screen, there's no CPU consumed on the
iSeries. CPU is only needed when there's something to do so the iSeries
swaps the job out (if needed) and focuses on the batch jobs until the
interactive job "wakes up" when the user submits the screen.

From what you've said so far I see no reason to worry about throttling batch

at this time.

On Thu, Nov 19, 2009 at 9:48 AM, John Allen <jallen@xxxxxxxxxxx> wrote:

I know this question will probably have multiple answers including "it
depends"



If we have a subsystem setup to run a set of specific batch jobs. And these
jobs are running at the default batch job run priority of 50

(subsystem setup with normal default values you get when subsystem is
created and the SBMJOB does not have anything but the default values
specified)



The interactive jobs are running at the default priority of 10



Why do the Batch jobs (there are 5 of them total running in the subsystem)
seem to be taking up to 60-70% of CPU while the interactive jobs are taking
.5 - 1% each

Or is this nothing to worry about, the System i will adjust resources as
necessary to keep the interactive response time unaffected by batch jobs?



I do not have users complaining about slow response times (yet) I just
noticed this and it got me wondering why is this?

And who knows if it continues they may start calling me.



Also, is there something I can easily so to reduce the CPU% the batch jobs
are taking?

Tmeslice, or memory or anything else?



Thanks

John









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