Decades ago, when some of us were first learning to code in C, we found a significant improvement in performance when we switched the datasets we were using for I/O from unblocked to blocked records. So it does make sense.
On Sun, Jan 19, 2025 at 4:13 PM Michael Oujesky <reflect...@oujesky.net> wrote: > I would suspect KSDS VSAM files that were being accessed randomly > without LSR processing. Use of LSR or conversion to sequential > processing is the suspected tweak. > > Michael > > At 09:06 AM 1/19/2025, Robert Prins wrote: > > > From LinkedIn: > > > ><quote> > >2 weeks ago I received the analysis data from a new client that wanted to > >reduce their CPU consumption and improve their performance. They sent me > >the statistical data from their z16 10 LPARS. Information about 89,000+ > >files. I analyzed their data and found 2,000+ files *that could be > improved* > >and would save CPU when improved. *I pulled out 1 file to demonstrate a > >Proof of Concept (POC) for the client. I had the client run the POC and it > >showed a 29% reduction in CPU every time that file will be used. The 29% > >did not include 3 other major adjustments that would save an addition 14% > >CPU and cut the I/O by 75%.* This is just 1 file. The other files can save > >3% to 52% of their CPU every time they are used in BATCH or ONLINE. > ></quote> > > > >I've been a programmer on IBM since 1985, and the above doesn't make any > >sense to me, how can changing just one file result in a 43% reduction in > >CPU usage? > > > >I've only ever been using PL/I, and using that I did manage to make some > >improvements to code, including reducing the CPU usage of a CRC routine by > >an even larger amount, 99.7% (Yes, ninety-nine-point-seven percent), but > >that was because the old V2.3.0 PL/I Optimizing compiler was absolute > shite > >at handling unaligned bit-strings, but WTH can you change about a file to > >get the above reduction in CPU? > > > >Robert > >-- > >Robert AH Prins > >robert(a)prino(d)org > >The hitchhiking grandfather <https://prino.neocities.org/index.html> > >Some REXX code for use on z/OS > ><https://prino.neocities.org/zOS/zOS-Tools.html> > > > >---------------------------------------------------------------------- > >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 > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
