[email protected] (Martin Packer) writes: > Ron, care to remind us of the modelling difference? It's been a while. :-)
360 & 370 dual-processors shared memory but each processors had its own dedicated channels ... and the configuration could be split and run as two separate processors. 370AP ... was a two processor configuration where only one of the processors had channels ... the second processor purely did compute bound work. it was less expensive and could be applicable to more compute intensive work. it was also applicable in large loosely-coupled environment when running out of controler interfaces for all the channels ... aka with four channel dasd controller with string-switch (for each disk connected to two controllers) ... giving 8 channel paths to each disk ... it would be possible to have eight two-processor complexes (for 16 processors total). DYADIC was term introduced with 3081 ... where it wasn't possible to split the configuration and run as two separate independent processors (wanted to draw distinction between past 360/370 multiprocessor that could be split and run independently and the 3081 which couldn't be split). 3081 had both processors being able to address all channels and also introducted 31-bit virtual addressing. trivia ... 360/67 had 32-bit virtual addressing, all processors could address all channels *AND* configuration could be split into independent running single processors. 360/67 was desgined for four-processor configuration, but I know of only a couple three-processor configuration that were actually built (and no four processor configurations) ... all the rest multiprocessor configurations were simply two-processors. other 3081 trivia ... 370 (& 3081) dual-processor slowed machine cycle down by ten percent to help with multiprocessor processor cache interaction ... so a two-processor machine started out at only 1.8 times a single processor machine. Multiprocessor software and actual multiprocessor cache interactions tended to add additional overhead so that dual-processor tended to have 1.4-1.5 times the throughput of single processor. 3081 originally never intended to have single processor version ... but largely because ACP/TPF didn't have multi-processor support, there was eventually a 3083 introduced. The easiest would have been to remove 2nd processor from the 3081 box ... however, processor0 was at the top of the box and the 2nd processor1 was in the middle of the box ... which would have left the box dangerously top heavy. eventually 3083 was introduced with single processor ... it was possible to turn-off the ten percent machine cycle slowdown (done for multiprocessor cache interaction) ... and eventually there was a special microcode load tuned for the ACP/TPF workloads that tended to be more I/O intensive. in the late 70s, the consolidated internal online US HONE operation (US HONE and the various HONE clones providied online world-wide sales & marketing support) was the largest single-system operation in the world. It was large loosely-coupled operation with "AP" multiprocessors ... most of the sales&marketing applications were implemented in APL and the workload was extremely compute intensive. I provided them with their initial multiprocessor support ... highly optimized kernel multiprocessor pathlengths and games played to improve cache hit locality ... could get slightly better than twice single processor (i.e. cache games offset the machine running at only 1.8times single processor and the optimized multiprocessor pathlengths). misc. past posts mentioning multiprocessor support (&/or compare&swap instruction) http://www.garlic.com/~lynn/subtopic.html#smp as mentioined in previous post http://www.garlic.com/~lynn/2011f.html#41 CPU utilization/forecasting the science center had done a lot of the early work in performance monitoring, reporting, simulation, modeling, workload&configuration profiling ... that evolves into capacity planning. misc. past posts mentioning science center http://www.garlic.com/~lynn/subtopic.html#545tech One of the APL models was packaged in the mid-70s as the "performance predictor" on HONE ... so that sales&marketing could take customer workload&configuration specification and ask "what-if" questions about workload &/or configuration changes. another version of the "model" was modified and used to decide (online) workload balancing across the loosely-coupled configuration (which processor complex would new logon be directed to, part of single-system operation). misc. past posts mentioning HONE http://www.garlic.com/~lynn/subtopic.html#hone -- 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: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
