Or as I said in 1974 ... https://books.google.com/books?id=XrgyMRVh128C&pg=PA16
(Gawd, I'm turning into Lynn Wheeler ... <g>) Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Skip Robinson Sent: Thursday, December 24, 2015 2:27 PM To: [email protected] Subject: Re: Is there a source for detailed, instruction-level performance info? This is in no way a personal comment on Tom's experience. 'What a programmer is supposed to do' is avoid stupid code. We were once tasked with finding the bottleneck in a fairly mundane VSAM application. It ran horribly, consuming scads of both CPU and wall clock. It didn't take long using an OTS product to discover that for every single I/O, the cluster was being opened and closed again even though nothing else happened in the meantime. Simply changing that logic slashed resource utilization. In another case, we were on the verge of upgrading a CEC when the application folks themselves discovered a few grossly inefficient SQL calls. Fixing those calls dropped overall LPAR utilization dramatically. What Tom and I are both saying is that focus on instruction timing should be seen as more of an avocation than a serious professional pursuit. Like playing with model trains at the expense of improving actual rail systems. It's interesting, but not much real business depends on the outcome. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
