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SAP IQ 16 hyperthreading

Oct 27, 2016 at 01:28 PM

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Hello,

We are planning to run SAP IQ 16 on Solaris 11 with 4 SPARC v9 processors and each one is able to "open" 8 threads. So according to IQ 16 HW sizing guide, it is possible to use the "virtual" threads, just the physical cores, meaning the "iqnumbercpus" parameter should be set to 4.

So , is there any way that IQ may somehow use those threads?

Thank you

Regards

Jose

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4 Answers

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Mark Mumy
Oct 27, 2016 at 06:54 PM
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IQ doesn't "use" threads, per se. IQ allocates threads at startup based on all logical cores (cores and threads per core) on the host. On Many platforms, this can over inflate the host size and cause poor performance. This is why we usually recommend that we set -iqnumbercpus to match the physical core count. This is just a guideline for IQ, though. There are startup parameters, like total threads, that are based on the -iqnumbercpus value. That does not mean that IQ is limited to just that count.

This is where the "IQ doesn't use threads" comes in to play. With -iqnumbercpus set to 4, there would be about 240 threads allocated. When a load or query runs, that query is optimized based on -iqnumbercpus. IQ then turns over the threads to the OS for execution. If a load needs 50 threads to run, then 50 threads are turned over to the OS for execution and scheduling. It could be that the OS runs all 50 simultaneously. It may run just 1. Or something in between.

The net is that just because you set -iqnumbercpus to the physical core count, it doesn't mean that it can't run on more cores and OS threads.

I am completely against leaving Solaris IQ -iqnumbercpus to be determined by the total threads on the host. In some cases, I think that just matching the physical core count is too low. I would start with matching the physical cores of 4 then see how IQ performs. If we don't see the host using all threads (4 cores*8 threads), then increase -iqnumbercpus to 6 or 8 and retest.

Mark

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Jose Torres Oct 27, 2016 at 07:33 PM
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Mark,

Thank you

Regards

Jose

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Amit Singh Nov 23, 2016 at 12:36 PM
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Use psrinfo along with cpuinfo command to know the Physical CPU,Cores & Logical Processor on the server.As Sparc Architecture is different , here you have to customize the Server accoring to the license in hands for the Cores and set the iqnumbercpus in the configuration file during startup. Ignore the Logical Processor count.

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Jose Torres Nov 24, 2016 at 03:53 PM
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Thank you Amit

Jose

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