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

Kirk,

I have to think you're either misremembering (maybe the 40% ave disk
usage recommendation), or the recommendation has changed.

Particularly in regards to batch processing; years ago I read an IBM
paper (that I can't find right now) that talks about getting the best
batch performance possible. One key method, restructure the job into
multiple jobs so that the CPU usage is driven as close as possible to
100%.

Charles

On Thu, Nov 19, 2009 at 11:50 AM, Kirk Goins <kgoins@xxxxxxxxxxx> wrote:

Charles Wilt wrote:

John,

If the users aren't complaining and the total CPU usage is less than
100%, then don't worry about how much the batch jobs are taking.

Look at it this way, if the CPU isn't 100%, then part of the time your
system is doing nothing....so how much did you pay for that
paperweight anyway? :)  Theoretically, you want the system to run at
95% or so all day long. Of course in real life, you've got workload
peaks & valleys, plus you want room for growth so you're not upgrading
every week.

The point is, why would you want to constrain the work being done for no reason?

Charles

Charles,

Sometime ago ( might need a 'WAY-BACK' Machine ) IBM used to tell us
that running a CPU over 60% would start to cause performance problems
with in the CPU. I don't remember the terms ( reason ) they gave but
something like thrashing if if was a disk comes to mind. The Higher and
Longer it ran that way the less real work was done.  Anyone remember
anything like this?

Maybe it was a Dream wishing for more horsepower :)


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