Author: Robert Sample
Subject: Reply to: MIPS/CPU consumption reduction in Batch
Posted: Mon Mar 20, 2017 7:25 pm (GMT 5.5)
From http://www.mainframes360.com/2014/02/sizing-up-your-mainframe-mips-and-msus.html (emphasis added by me):
and from IBM's LSPR capacity ratios web site at https://www-304.ibm.com/servers/resourcelink/lib03060.nsf/pages/lsprITRzOSv2r1?OpenDocument :
So IBM tells you not to use MSU (and by extension MIPS) as a capacity measure. This is reinforced by IBM's Systems Magazine (this article dates to November 2004, so IBM has been telling people for a LONG time not to use MIPS) at http://www.ibmsystemsmag.com/mainframe/tipstechniques/systemsmanagement/Don-t-Be-Misled-By-MIPS/ (again, emphasis added by me):
If you start Googling ibm mips, you can find about 486,000 web sites and many of them talk about how MIPS has not been valid for comparisons or measuring performance for decades.
_________________
TANSTAAFL
The first rule of code reuse is that the code needs to be worth re-using.
"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil." -- Donald Knuth
Subject: Reply to: MIPS/CPU consumption reduction in Batch
Posted: Mon Mar 20, 2017 7:25 pm (GMT 5.5)
From http://www.mainframes360.com/2014/02/sizing-up-your-mainframe-mips-and-msus.html (emphasis added by me):
| Quote: |
| Speed or performance of a computer is measured in Millions of Instructions per second (MIPS). In the early days, mainframe capacity was measured by running a standard routine over and over again. For example, an early IBM S/370 computer could run 1 Million instructions a second. However, MIPS is an no longer used to measure speed. Mainframe computers have simple as well as complex instructions. A program of 5 million complex instructions takes lot more time than a program of 5 million simple instructions. Complex instructions take more CPU cycles. Many computer engineers jocularly dubbed MIPS as âmisleading indicator of performanceâ. CPU seconds is still often, used by programmers to measure performance and chargeback. The problem is that the work done by a zEC 12 machine in one CPU second is not the same as other mainframe computer models. One z12 CPU second is different from one z10 CPU second. So, IBM introduced a standard measure called Service Units (SU). SUâs and MSUâs are an ingenious way to measure mainframe capacity irrespective of the processor or the workload. |
| Quote: |
| *** MSUs are used for software pricing only; they are not a capacity metric. |
| Quote: |
| One of the most misused terms in IT has to be MIPS. It's supposed to stand for "millions of instructions per second," but many alternate meanings have been substituted: Misleading indicator of processor speed Meaningless indicator of processor speed Marketing indicator of processor speed Managements impression of processor speed Jokes aside, management has a tendency to want one figure to represent a processor's capacity. And companies are spending large amounts of money based on a poorly understood indicator, for both software and hardware acquisitions. Unfortunately, no one number describes capacity. Processor speed varies depending on many factors, including (but not restricted to): Workload mix Memory/cache sizes I/O access density Software levels (OS and application subsystems) Hardware changes Partitioning Workload mix is the largest contributor to the variability of capacity figures. |
_________________
TANSTAAFL
The first rule of code reuse is that the code needs to be worth re-using.
"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil." -- Donald Knuth