CPU Consumption in Common Area

Virendra Shambharkar · New User Joined: 26 Aug 2015 Posts: 55 Location: India

Hi ,

We have a job that is continuously polling MQ to read data . If there is no data in MQ it goes to MQ wait and then again polls the MQ to read . Other than this it does not do any other function.It runs for 10-12 hours and is showing to consume around 1 hour of CPU in JESYSMSG .

A STROBE report on this job shows 80 % of CPU in common area . The Program Usage by Procedure sections (PSU) shows 80 % in module name as COMMON as system service description as 'EXTENDED COMMON AREA'.

Can you help me understand why the CPU consumption in Common area and if there is any pointer on optimization for the same.

Thanks,
Virendra

steve-myers · Posted: Tue Sep 08, 2015 6:31 pm

Many programming systems load modules that must be in shared storage (that is, storage available to all address spaces) into the “common” storage area rather than place the module into LPA. Alternatively, if the module is small, it is simply copied into common storage. It appears the MQ executive is doing the latter since the module is not in the list of modules known to the system.

There is a fundamental difference between 80% of the CPU and 80% of the time in the program, if the program is using, say, 1% of the total CPU capacity. If your program is periodically waking up and checking if there is a message, “optimizing,” or in your context, reducing this time is a matter of the design of the MQ programming system and is properly a matter to be discussed with IBM's MQ support.

Marso · Posted: Tue Sep 08, 2015 7:58 pm

Which value do you have for MQ wait interval ?

Virendra Shambharkar · New User Joined: 26 Aug 2015 Posts: 55 Location: India

Thanks on further research we found program BPXWDYN is called down the line which is TSO command executor program . COMMONX is related to MVS and we suspect because of this module there is MVS involvement which could cause more CPU.

Thanks a lot.

enrico-sorichetti · Posted: Wed Sep 09, 2015 1:14 pm

I doubt that BPXWDYN calls could be the cause for a <high> CPU utilisation

Virendra Shambharkar · New User Joined: 26 Aug 2015 Posts: 55 Location: India

Not the calls but loading of the module could be causing high CPU . Since COMMONX relates to loading program at run time . I got reference from below:-

www.idug.org/p/fo/et/thread=3965

enrico-sorichetti · Posted: Wed Sep 09, 2015 2:25 pm

the link You posted also tells that

Virendra Shambharkar · New User Joined: 26 Aug 2015 Posts: 55 Location: India

Thanks Enrico . Is there a way to identify what are the modules/subroutines that belong to COMMONX.

Thanks,
Virendra

steve-myers · Posted: Wed Sep 09, 2015 5:12 pm