[email protected] (Edward Finnell) writes: > For decades MVS has honored the concept of public, Storage and private > DASD. Numerous SHARE papers on how to configure DASD subsystems in > order to reduce contention and optimize thruput. WSC under Ray Wicks > produced many of them. One of my favorites was the 'The Big > Pitcher'. Properly administered SMS can enhance the basic concepts and > augment them with storage overflow. > > If we had more info on the problem better suggestions could be > provided. One of the old tricks was to preallocate sortwks and pass > them thru the life of the job. No need to worry about vol=ref
back when CKD were real ... (rather than various kinds of simulation on industry fixed-block disks ... all that rotational positioning and arm motion, track lengths ... are all fiction) ... I was increasingly pointing out that disk wasn't keeping up with computer technology and by the early 80s was saying that disk relative system throughput had declined by a factor of ten times since the 60s (disk throughput increased 3-5 times, processor and memory throughput increased 40-50 times). Some disk division executive took exception and assigned the division performance group to refute the statements. after several weeks they eventually came back and effectively said that I had slightly under stated the problem. The analysis was then respun as disk configuration recommendations for improving system throughput ... SHARE presentation B874. old post with part of the early 80 comparison http://www.garlic.com/~lynn/93.html#31 old posts with pieces of B874 http://www.garlic.com/~lynn/2001l.html#56 http://www.garlic.com/~lynn/2006f.html#3 note that memory is the new disk ... current latency for cache miss, memory access ... when measured in count of processor cycles is similar to 60s disk latency when measured in 60s processor cycles .... it is part of the introduction of out-of-order execution, branch prediction, speculative execution, hyperthreading ... stuff that can go on while waiting on stalled instruction (waiting for memory on cache miss) .... these show up in z196 (accounting for at least half the performance improvement over z10) ... much of this stuff have been in other platforms for decades. trivia: 195 pipeline had out-of-order execution ... but no branch prediction and/or speculative execution ... so conditional branches stalled the pipeline, most applications would only ran at half 195 rated performance. I got dragged into proposal to hyperthread 195 ... two instruction streams simulating multiprocessor ... two simulated processors running programs around half throughput ... then would keep 195 running at rated speed. It was never done ... IBM hyper/multi threading patents mentioned in this post about the end of ACS/360 https://people.cs.clemson.edu/~mark/acs_end.html from Amdahl interview in the above: IBM management decided not to do it, for it would advance the computing capability too fast for the company to control the growth of the computer marketplace, thus reducing their profit potential. I then recommended that the ACS lab be closed, and it was. ... snip ... end of the article has some of the acs/360 features that show up more than 20yrs later in es/9000. -- 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
