On Tue, 10 Feb 2009 09:46:12 -0600, Brian Nielsen <bniel...@sco.idaho.gov > wrote:
>To answer your question #2: Once a guest has a slot on a CP paging devic e >it will be there essentially for the life of the guest, barring somethin g >like a DEF STOR. It doesn't look like the CMMA stuff extends to freeing >paging slots when a guest discards pages. > >Brian Nielsen > This isn't typically true, either. If a page on DASD is brought back in to storage (either because it was referenced by the guest, or part of a pagi ng block where any page in the block was referenced by the guest), the old paging slot from which the page was read will typically be released (free d). The only cases where the old slot would be retained is if the page was never brought in again, or where it was brought in as a non-faulted page as part of a paging block, and then never again referenced or changed (relatively unlikely). CMMA action causing a page to revert to the logically zeros state would also typically release any paging slot associated with the old page contents. There will typically be some numb er of pages, however, that are referenced only at guest startup or perhaps a t very infrequent guest state transitions, and such pages will tend to rema in "in place" on paging space for long periods of time. - Bill Holder, z/VM Development, IBM Endicott
