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-iqnumbercpus vs -gt

serkan_birkan
Explorer
0 Kudos

Hello,

What is the difference between -iqnumbercpus and -gt options in IQ? Can they be used instead of each other?

Thanks in advence.

Accepted Solutions (1)

Accepted Solutions (1)

saroj_bagai
Contributor
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-gt :  Sets the maximum number of physical processors that can be used (up to the licensed maximum).
This option is only useful on multiprocessor systems.

Syntax
start_iq -gt <num-processors> ...


Allowed values

•num-processors
This integer can be a value between 1 and the minimum of:
◦the number of potential physical processors on the computer
◦the maximum number of CPUs that the server is licensed for if CPU-licensing is in effect

If the -gt value specified lies outside this range, the lower or upper limit is imposed.


Remarks


With per-seat licensing, the network database server uses all CPUs available on the computer.
With CPU-based licensing, the network database server uses only the number of processors
you are licensed for. The number of CPUs that the network database server can use may also be restricted
by your SAP IQ edition.

When you specify a value for the -gt option, the database server adjusts its affinity mask
(if supported on that hardware platform) to restrict the database server to run on only that number of physical processors. If the database server is licensed for <n> processors, the server, by default, runs on all logical processors (hyperthreads and cores) of <n> physical processors. This behavior can be further restricted with the -gtc option.

The -gt option cannot be used with the -gta option.


- iqnumbercpus database server option


Specifies the number of CPUs available to SAP IQ, overriding the physical number of CPUs, for resource planning purposes.

Syntax
start_iq -iqnumbercpus <num>


Remarks


The value of -iqnumbercpus defaults to the total number of CPUs, but the range of available values is 1 – 512.

Use -iqnumbercpus only on:•Machines with Intel CPUs and hyperthreading enabled, setting -iqnumbercpus to the number of CPU cores available
•Machines where an operating system utility has been used to restrict SAP IQ to a subset of the CPUs within the machine
Setting -iqnumbercpus higher than the number of available CPUs may affect performance.

serkan_birkan
Explorer
0 Kudos

Thank you for the response, however I have already read the document. I think the "physical processors" and "physical CPUs" terms indicates different concepts, is it right? Otherwise the difference between -iqnumbercpus and -gt is still unclear for me.

markmumy
Advisor
Advisor
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-Iqnumbercpus is a soft limit. We do not cap resources at this level but rather try to size our resources based on this. Basically, we can exceed this value if the OS wants to schedule our work on more cores.

-gt a hard limit.  We will not under any circumstances exceed this value.

For instance, assume that the machine has 20 cores.

IF we set -gt to 10, only 10 cores will ever be used. If we set -iqnumbercpus to 10 we will optimize for 10 but could use all the way up to 20 cores.

Mark

serkan_birkan
Explorer
0 Kudos

Thank you very much Mark.

Answers (0)