[email protected] (Shmuel Metz , Seymour J.) writes: > No, that is not how conditional branching in channel programs has > always worked.
re: http://www.garlic.com/~lynn/2014c.html#62 Optimization, CPU time, and related issues http://www.garlic.com/~lynn/2014c.html#64 Optimization, CPU time, and related issues note in the middle 70s ... they consolidated all the US HONE systems (worldwide online sales&marketing support) in silicon valley (when FACEBOOK started they moved into a new bldg built next door to the old US HONE datacenter ... this is before FACEBOOK took over the old SUN campus). http://www.garlic.com/~lynn/subtopic.html#hone Part of the effort for HONE was creating the largest single-system image loosely-coupled operation in the world (of multiprocessor systems). Normal operation had been to use disk controller RESERVE/RELEASE commands for loosely-coupled operation (analogous to LOCK/UNLOCK operations in tightly-coupled multiprocessor operation). However, a (much more efficient) "compare&swap" channel program was developed. A full-track record was defined for each disk. A processor did read of the record ... and updated the image to reflect the resources it would be using ... and then did a compare&swap channel program ... basically search (data) equal on the record ... and if succesful would do a write operation with the updated record ... otherwise the operation would fail. This cluster operation supported workload throughput load-balancing and failure recovery across the complex. In part because of earthquake concerns the Cal. datacenter was replicated first in Dallas and then a 3rd in Boulder in the early 80s (could do load balancing and failure recovery across all 3 datacenters ... but somewhat more complicated). Of course none of this cluster support was ever released to customers ... a little of similar support finally recently leaking out 30yrs later: http://www.garlic.com/~lynn/2009p.html#43 From The Annals of Release No Software Before Its Time http://www.garlic.com/~lynn/2009p.html#46 From The Annals of Release No Software Before Its Time http://www.garlic.com/~lynn/2011m.html#46 From The Annals of Release No Software Before Its Time http://www.garlic.com/~lynn/2011m.html#47 From The Annals of Release No Software Before Its Time http://www.garlic.com/~lynn/2011m.html#59 From The Annals of Release No Software Before Its Time This was about the time my wife was con'ed into going to POK to be in charge of (mainframe) loosely-coupled architecture and came up with peer-coupled shared data architecture ... some past posts http://www.garlic.com/~lynn/submain.html#shareddata however, it found little uptake (except for IMS hotstandby) until sysplex & parallel sysplex ... which contributed to her not staying long in the position. Another factor was that the SNA forces were constantly trying to force her into using SNA for loosely-coupled operation ... there would be temporary truces where she could do whatever she wanted within the walls of the datacenter (SNA "owned" everything that crossed the datacenter wall) ... but then they would start attacking again. re: reserve/release, compare&swap channel program ... modulo not having ACP-RPQ locking installed on 3830 disk controller. some past refs: http://www.garlic.com/~lynn/2008i.html#39 American Airlines http://www.garlic.com/~lynn/2008j.html#50 Another difference between platforms http://www.garlic.com/~lynn/2011b.html#12 Testing hardware RESERVE and of course, the compare&swap instruction was originally invited by charlie when he was doing fine-grain multiprocessor locking for cp67 at the science center (name of instruction chosen because CAS are charlie's initials). past posts mentioning multiprocessor &/or compare&swap instruction http://www.garlic.com/~lynn/subtopic.html#smp -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
