Sorry: "... key-related instructions simply to access key9 storage."
-jc- > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On > Behalf Of Chase, John > Sent: Friday, August 29, 2014 7:55 AM > To: IBM-MAIN@LISTSERV.UA.EDU > Subject: Re: Is there a CPU cost to using key9 storage while running with key8 > > > -----Original Message----- > > From: IBM Mainframe Discussion List On Behalf Of David Price > > > > What hardware are you on? > > > > I ask because a z196 has some high CPU costs for certain PSW Key-related > > instructions. > > > > For example, SPKA (Set PSW Key from Address) on a z196 shows up in > > CICS CPU figures because it stalls the pipeline when changing PSW keys > > between key 8 and key 9 -- or even when it doesn't change keys e.g. it is > > just 'going' from key 8 to > key 8! > > > > SPKA may be executed in CICS more than you think (consider User Exits > > -- GLUEs and TRUEs -- some of which may have been inserted by your > > monitoring software). > > An interesting observation. I'd have thought that CICS (in particular), in > an early stage of startup > when it runs authorized, would set the "Storage-Protection-Override Control" > (bit 39 of CR0) if > STGPROT=YES was specified as a DFHSIT parm. See z/Architecture Principles of > Operation, 10th Edition, > at page 3-12 for details of "Storage-Protection-Override Control". > > This would seem to obviate any need for CICS, post-initialization when > running unauthorized, to issue > SPKA or similar key-related instructions. > > -jc- > > ********************************************************************** > Information contained in this e-mail message and in any attachments thereto > is confidential. If you > are not the intended recipient, please destroy this message, delete any > copies held on your systems, > notify the sender immediately, and refrain from using or disclosing all or > any part of its content to > any other person. > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send email to > lists...@listserv.ua.edu > with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
