The following message is a courtesy copy of an article that has been posted to bit.listserv.ibm-main,alt.folklore.computers as well.
[email protected] (David Stephens) writes: > I've always thought that a page fault in any operating system, > including z/OS, would generate an interrupt. The task requiring the > missing page would be put aside whilst RSM did the required I/O to the > page datasets (unless the page was already in memory - in expanded > storage, or a stolen page). However, I haven't been able to find any > mention of this interrupt (Principles of Operation mentions the six > interrupt types), and how it works. > > Can anyone clear this up? Does a page fault generate an interrupt like > a program exception? If so, what sort? If not, what happens? re: Principles of Operation http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/DZ9ZR003/CCONTENTS?SHELF=DZ9ZBK03&DN=SA22-7832-03&DT=20040504121320 see "Section 6.5 Program Interuption" & various things called "translation exception". slightly older version ... 360/67 (from 1967): http://www.bitsavers.org/pdf/ibm/360/funcChar/A27-2719-0_360-67_funcChar.pdf see pg. 17 & two program interrupts, "segment translation" and "page translation". it is possible to have page translation exception program interrupt if the page invalid bit is on in the page table entry (possibly indicating that the page isn't in memory). it is also possible to have segment translation exception program interrupt if the segment invalid bit is on in the segment table entry (possibly indicating that the page table hasn't been built yet). when i did table migration in the mid-70s ... i used the segment invalid bit in the segment table entry to indicate that the corresponding page table information wasn't available. some old email references: http://www.garlic.com/~lynn/2006v.html#email731212</a> http://www.garlic.com/~lynn/2006w.html#email750102</a> http://www.garlic.com/~lynn/2006w.html#email750430</a> in cp67, i had gotten the avg total pathlength to take an page-fault interrupt, select a page to be replace, build & initiate page fetch I/O operation, perform task switch, take the page fetch i/o interrupt, clean-up the operation and reschedule the original task ... down around 500 instructions (that includes prorated cost of doing page write when a changed page had been selected for replacement ... between 1/3rd and 1/2 of the time). -- 40+yrs virtualization experience (since Jan68), online at home since Mar1970 ---------------------------------------------------------------------- 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
