NUMCPUVPS entry in onconfig.gic
We are going to load Informix ODS 7.3 on DEC ALPHA 4000 Server with 2
processors. What should be the NUMCPUVPS entry in this case?. Informix
recommends this value to be one less than the total no of processors. When
we are running on a single processor machine, the entry is 1 in ONCONFIG.GIC.
NUMCPUVPS 1 # Number of user (cpu) vps
If the value still remains 1 ( 2 minus 1 ), when it is a two processor
machine , what difference it does it make? What should be the value?
Thanks in advance
Sampath
The recommendation is made to allow for one CPU for the engine and one for
other activities. If you are using the computer STRICTLY as a server, you
can up the value to 2. If you set NUMCPUVPS to 1, you should also set
SINGLE_CPU_VP to 1. This will allow the code that has been optimized for a
single CPU.
Note that you can still set the environment variable PSORT_NPROCS to 2 to
use the 2nd processor for sorts (order bys, group bys, Update Statistics,
index creations).
Take care.
Clifton
sampath aravamudhan wrote in message <7a3723$j6p$1@news.xmission.com>...
>
>We are going to load Informix ODS 7.3 on DEC ALPHA 4000 Server with 2
>processors. What should be the NUMCPUVPS entry in this case?. Informix
>recommends this value to be one less than the total no of processors. When
>we are running on a single processor machine, the entry is 1 in
ONCONFIG.GIC.
>
>NUMCPUVPS 1 # Number of user (cpu) vps>
>If the value still remains 1 ( 2 minus 1 ), when it is a two processor
>machine , what difference it does it make? What should be the value?
>
>Thanks in advance
>
>
>Sampath
>
>
>
>
>
>
===============================================
Clifton M. Bean cbean@informix.com
INFORMIX Support Engineer
16011 College Blvd
Lenexa, KS 66219
INFORMIX Phone: 800-274-8184
Fax: 913-588-8590
===============================================
Hi Sampath,
In answer to your question, your research is correct.
Informix recommend NUMCPUVPS = Total CPU's - 1.
The reason for this recommendation is to allow the OS to also have a CPU.
If you make them equal you can have lots of fun on some platforms especially
if you decide to use NOAGE.
I recommend that you make NUMCPUVPS = 1 and also set in conjunction with the
SINGLE_CPU_VP = 1, also if the DEC platform supports it you set NOAGE = 1.
The reason for my recommendation is when running on a 2 processor machine
with 1 CPU VP you will incur the overhead that goes with multi processor
communications. Hence by setting SINGLE_CPU_VP you are telling oninit to
have 1 CPU VP and not to consider any form of Multi CPU Communications hence
allowing the oninit process to perform faster.
The NOAGE, if supported (Check your release notes under
$INFORMIXDIR/release) will ensure that the OS does not perform priority
ageing on the oninit process.
I hope this helps to answer your questions.
Regards
Sean
sampath aravamudhan wrote in message <7a3723$j6p$1@news.xmission.com>...
>
>We are going to load Informix ODS 7.3 on DEC ALPHA 4000 Server with 2
>processors. What should be the NUMCPUVPS entry in this case?. Informix
>recommends this value to be one less than the total no of processors. When
>we are running on a single processor machine, the entry is 1 in
ONCONFIG.GIC.
>
>NUMCPUVPS 1 # Number of user (cpu) vps>
>If the value still remains 1 ( 2 minus 1 ), when it is a two processor
>machine , what difference it does it make? What should be the value?
>
>Thanks in advance
>
>
>Sampath
>
>
>
>
>
>
Note also that if you use CPU affinity (supported on DEC platforms) then you
should
pin your CPU VP to second CPU ...
AFF_SPROC 1
AFF_NPROCS 1
This may improve performance by leaving first CPU to Unix, and second to
Informix CPU VP.
Regards
==============================
Slobodan Zorko
Alfatec Group
10000 Zagreb, Kranjceviceva 36, CROATIA
email: slobodan.zorko@zg.tel.hr
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