Timeslice/purge settings was: Suppress Query Status Message

[Buck Calabro/commsoft<mcalabro@xxxxxxxxxxxx>]

On 03/17/99 05:46:43 PM pytel wrote:

Alexey,

>Timeslice and Purge settings will not have any noticable influence on
>long-running tasks.

This is a very interesting topic!
Doesn't TIMESLICE come into play when you have a compute-bound job? 
Something like creating large GDDM graphics?  When the job goes to disk to 
get/put a record, it leaves the activity level, right?  Unless the job 
occupies the activity level until timeslice end, boosting the timeslice 
makes no difference

The purge setting is mostly useful in a small-memory system, if I recall. 
It lets you tell the system if you want the entire PAG paged in one 
operation at timeslice end/enter long wait.

This leaves RUNPTY as the other parameter on the class.  Won't a job that 
fetches thousands of pages of DASD at RUNPTY(20) will be more of a resource 
hog than the same job running at 50?  It'll certainly get returned to an 
activity level before the RUNPTY(50) job will.

So, I guess the question here is: for a query, does the processor time 
required to build an access path get charged to the interactive job, or to 
an internal system task?

The batch/interactive debate extends into separate memory pools and working 
set size.  Too often, the interactive memory pool is sized for a smaller 
working set that the batch pools.  This makes it easier for a batch-type 
job to force other jobs' storage to be paged out.  This is not a Good Thing 
for the interactive job's program pages that've been paged out by DB pages.

>Suppressing status messages can help, because sending message to display
>device incurs a relatively high overhead (especially when there are many).

Absolutely!  The same is true for writing messages to the job log.  Any 
time a program/job does extra I/O is a place to look for performance 
improvements.

Buck Calabro
Billing Concepts Inc (formerly CommSoft), Albany, NY
mailto:mcalabro@commsoft.net
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