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MIPS/CPU consumption reduction in Batch

 
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vishwakotin

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Joined: 15 Mar 2017
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Location: India

PostPosted: Sat Mar 18, 2017 5:46 pm    Post subject: MIPS/CPU consumption reduction in Batch
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Hi,

I am into a project where I need to reduce the CPU consumption for the batch application. I want to know all the methods which are available to do it, it may be optimizing SORT, tuning SQL any other utilities which takes less CPU.

Thanks,
Vishwa
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Bill Woodger

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Joined: 09 Mar 2011
Posts: 7313

PostPosted: Sat Mar 18, 2017 6:02 pm    Post subject: Reply to: MIPS/CPU consumption reduction in Batch
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You look for the ways things are done badly. and change them to do things well.

The ways things can be done badly are legion. There's no simple list.

Look for the heavy CPU users, especially in relation to the number of inputs.

As your Production Control, Storage, Support and other technical staff is they are aware of "anomalies" with your systems.

Paying someone who has experience of this would be the most effective way, but perhaps your client is already sold on the idea that within your team there are skill for this.
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Robert Sample

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Joined: 06 Jun 2008
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Location: East Dubuque, Illinois, USA

PostPosted: Sat Mar 18, 2017 6:36 pm    Post subject:
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First, unless you find a way to reduce the number of records being sorted, "optimizing SORT" is generally futile -- SORT has already been very optimized and there is usually little that can be done to reduce CPU usage.

Second, you need a run-time analysis program (such as STROBE) to be effective at reducing CPU usage. Programmers are generally poor at understanding what causes their programs to use CPU time, and hence having a tool will be vastly helpful.

Third, your best candidate for CPU reduction will be the SQL code. However, you may have to add disk space (for indexes, as one example) in order to reduce CPU usage.

Fourth, as Bill suggested -- talk to your production support group; they most likely know the best candidates to look at for CPU reduction!

Fifth, your post title "MIPS/CPU consumption reduction in Batch" is completely wrong. MIPS is a measurement that should NEVER be applied to anything less than the entire machine. MIPS can be reduced by removing the current machine and replacing it with a slower machine -- MIPS cannot otherwise be reduced. Yes, it is common to use MIPS and CPU interchangeably -- but they are not the same and should NEVER be swapped!
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vishwakotin

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Joined: 15 Mar 2017
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PostPosted: Mon Mar 20, 2017 12:03 pm    Post subject:
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Thanks Bill and Robert. I will check these once I get into the project.

Robert - Thanks for your detailed explanation on the difference between MIPS and CPU.

Please send me some more links for this reference if you have.

Thanks,
Vishwa
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Robert Sample

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Location: East Dubuque, Illinois, USA

PostPosted: Mon Mar 20, 2017 7:25 pm    Post subject: Reply to: MIPS/CPU consumption reduction in Batch
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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 “misleading indicator of performance”.

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). SU’s and MSU’s are an ingenious way to measure mainframe capacity irrespective of the processor or the workload.
and from IBM's LSPR capacity ratios web site at https://www-304.ibm.com/servers/resourcelink/lib03060.nsf/pages/lsprITRzOSv2r1?OpenDocument :
Quote:
*** MSUs are used for software pricing only; they are not a capacity metric.
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):
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.
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.
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