Thank you!

Richard Pinion



"Confidentially doc, I am the wabbit."

Bugs Bunny

Sent with Proton Mail secure email.

On Wednesday, July 15th, 2026 at 8:35 AM, Rob Scott 
<[email protected]> wrote:

> Richard
> 
> The overhead to the fetch-causer is very minimal as SDSF MFM works by having 
> a CSVFETCH dynamic exit that copies the payload from the FTCHX parameter list 
> into a circular HV-COMM queue. The path length is quite small.
> 
> The overhead you might see is extra CPU used in the SDSFAUX address space, 
> specifically the HSFMFMMN subtask as it periodically drains the HV-COMM queue 
> and processes the payloads.
> 
> Depending on your requirements, you can select 3 levels of detail on the 
> FEATURE statement in ISFPRMxx :
> 
> Level(1) - SDSF summaries the data on just the dsname
> Level(2) - SDSF additionally summarizes the data by dsname+modname
> Level(3) - SDSF additionally summarizes the data by dsname+modname+jobname
> 
> Also note that you can dynamically start and stop the MFM feature at any time 
> using "F SDSF,S MFM" and "F SDSF,P MFM". The processed data is kept until you 
> issue "F SDSF,R MFM" which will reset the summary tables in SDSFAUX private 
> storage.
> 
> You can track MFM statistics with "F SDSF,D MFM" and the SDSF task CPU usage 
> with "F SDSF,D TASK"
> 
> Hope that helps
> 
> Rob Scott
> Rocket Software
> ________________________________
> From: IBM Mainframe Discussion List <[email protected]> on behalf of 
> rpinion865 <[email protected]>
> Sent: 15 July 2026 10:08 AM
> To: [email protected] <[email protected]>
> Subject: SDSF MFM Feature
> 
> EXTERNAL EMAIL
> 
> 
> 
> 
> Does anybody have information regarding the SDSF MFM feature and CPU 
> usage/overhead?
> I have turned it on for the TECH and Development LPARs. But I am concerned 
> about what
> might happen on the Production LPAR. Thanks in advance.
> 
> Richard Pinion
> 
> "Confidentially doc, I am the wabbit."
> 
> Bugs Bunny
> 
> Sent with [Proton 
> Mail](https://proton.me/mail/home<https://proton.me/mail/home>) secure email.
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