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bijoybabu83
New User
Joined: 15 Jan 2007 Posts: 36 Location: Kerala
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I have to do some processing and write some data to a 5 files based on some conditions. But one file is no longer needed. So i put that file to dummy in the jcl like 'dd dsn=dummy' instead of DD DSN=&&SHORTS,DISP=(,PASS).
Will this save performance. Will this save cpu cycles. |
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mmwife
Super Moderator
Joined: 30 May 2003 Posts: 1592
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Hi Babu,
Yes, and more importantly, it eliminates the wait time inherent in writing data to a device. |
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bijoybabu83
New User
Joined: 15 Jan 2007 Posts: 36 Location: Kerala
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Hi ,
Thanks for your Prompt help.
One more question I do have is will it take any CPU cycles if we put dd dummy.
Thanks,
Babu - |
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Terry Heinze
JCL Moderator
Joined: 14 Jul 2008 Posts: 1249 Location: Richfield, MN, USA
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I don't think CPU cycles will be affected one way or the other. Where you save is I/O time which is where 99% of your time goes anyway. Also, CPU cycles aren't nearly as critical as they were years ago. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006 Posts: 19244 Location: Inside the Matrix
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Hello,
All "write"s take some cpu overhead - dummy uses the least.
If you are really interested in cpu use, you could change the code so that the file is no longer referenced in the code. The data moves/calculations to build the output "record" take more cpu than the dummy write. . . |
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