"Walter Marguccio" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>... > Dear listers, > > reading Cheryl Watson's last Tuning letter one sentence about the Upgrade ROT caught my attention: > "Only add resources as needed. If you add more memory than you need, you'll simply cause CPU overhead". > My first question is how could more memory cause CPU overhead ? > Our production LPAR (z/OS.e 1.4 on a z890) has 5 GB storage assigned; RMF shows an average of 25% of the total frames as active, > while the remaining 75% is available. Now and again we have jobs which do need more frames, so the percentage varies > to show 60% or 70% active and 40% or 30% available, but that's sporadic. > Should I consider the storage assigned to our LPAR as too much ? Any chance that the assigned storage would cause CPU overhead ? > > I'd like to read your opininion/ROT on this. > > Best regards > > > Walter Marguccio > z/OS Systems Programmer > Munich - Germany >
Theoratically it is true of course: storage must be managed and more storage means more frames to examine, larger tables to run through etc. An unused unit of storage must be examined, determined that it is unused and actions (statistics) are taken for unused storage. If this storage is just not there, less activity is needed. For your terminology: all assigned storage costs CPU overhead, less storage might result in less overhead. Writing this, I realize that the benefit must not be wasted on the other hand on slightly higher paging. I am curious to see if measurements are available on the actual costs of overallocating storage and on determining the optimum. Kees. ********************************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. Koninklijke Luchtvaart Maatschappij N.V. (also known as KLM Royal Dutch Airlines) is registered in Amstelveen, The Netherlands, with registered number 33014286 ********************************************************************** ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
