Re: Memory Pool questions

[DrFranken <midrange@xxxxxxxxxxxx>]

You are on target pretty well.   I do like performance adjustment turned 
on but as you notice it leans HEAVILY toward Interactive since that is 
the O/S' heritage. To fix that go into WRKSHRPOOL and hit F11 enough 
times to get to the tuning values.  Interact will have a 10% minimum so 
drop that to perhaps 1 in your case. You can also lower it's priority to 
2 perhaps and raise the max faults. (Though your faults are well below 
the base maximum.) You might want to even drop the max percentage to 
keep it from growing too big.

Since the advent of threaded jobs the Active->Waits has become a very 
large number since it reflects threads not jobs so that's no problem at 
all.

Having performance adjustment set at 0 is acceptable if your workload is 
pretty static but if you toss in a big SQL task into a pool set too 
small it may perform poorly and the O/S can't assist it.

Someone suggested setting *FIXED for the paging option but misunderstood 
what that means. It doesn't fix the size of the pool rather it tells the 
O/S not to observe the behavior of jobs and adjust paging to match. For 
example if you are reading a file sequentially it may pull in a lot of 
records if memory is available when set to *CALC but if set to *FIXED it 
will not.

As cool as memory pools are be careful not to simply create a big ol 
bunch of 'em or you'll fragment memory too much to be effective.

Another cool feature of pools is to pull objects into memory with 
SETOBJACC. Read up on that one if interested.

        - Larry "DrFranken" Bolhuis

www.Frankeni.com
www.iDevCloud.com - Personal Development IBM i timeshare service.
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On 1/27/2016 1:16 PM, Aaron Bartell wrote:

> Preamble...
> I've been playing with memory pools the past two weeks.  I also installed
> iDoctor to learn more about what is consuming CPU/memory/IO.  I have set
> QPRFADJ to '0' so I can adjust memory pools and have them stick.
>
> Side note: Memory pools rock.  Very cool feature, IBM i.
>
> Questions...
> - Is it a bad idea to set QPRFADJ to '0'?  My reason is that I don't want
> the *INTERACT pool to have much because I'd rather it be dedicated (always)
> to *BASE (where my open source/ssh is running).
>
> - In reviewing iDoctor ActiveJobs screen it appears my 5250 sessions are
> the only things operating on *INTERACT, so I think I am safe lowering this
> value from 600MB to 40MB.  Having it at 40MB hasn't been uncomfortably slow
> (going on a week now).    Are there any gotchas with setting it so
> low?(i.e. other types of jobs that I am not yet seeing)
>
> - The IBM docs(n1) say "The memory pool size should be large enough to keep
> data transfers (paging) at a reasonable level as the rate affects
> performance."  Well, the obvious next question is "what is reasonable"?  I
> consistently see "Active Wait" for *BASE at 3200-3500 and "Non-DB Faults"
> around 15 and "Non-DB Pages" around 37. This seems like a reasonable amount
> of faults given I am trying to do a variety of heavy lifting things all at
> once.  This would also lead me to believe my system currently has enough
> memory at its disposal and if I am looking for next areas of improvement I
> should look to CPW.
>
> n1 -http://bit.ly/ibmi-about-memory-pools
>
> Aaron Bartell
> litmis.com - Services for open source on IBM i