IDS Forum

Re: CPU Help

Posted By: Art S. Kagel (Oninit LLC)
Date: Wednesday, 28 November 2007, at 3:06 p.m.

In Response To: RE: CPU Help (Demeis, Tony (MOH))

Demeis, Tony (MOH) wrote:

Here's the scoop. The resource known as a VP is a virtual processor,
literally a copy of the engine's oninit process. VPs come in several
classes the most commonly configured of which are the CPU VPs which
process queries and AIO VPs which process COOK file IO (or all IO if
KAIO is turned off as it is by default when IDS runs under HPUX). If
you have KAIO turned on (see kio threads in the onstat -g iov output?
Yes KAIO is on, NO it is off) KAIO threads in the CPU VPs handle all RAW
disk IO (and IO to COOKED disk if DIRECT_IO is available - see below)
while the AIO VPs handle only COOKED file IO (COOKED chunks and the
message log and similar file IO).

As to how many of each? For a dedicated server you can run at least one
CPU VP per CPU core. What the reports you quote mean in those terms I
don't know. When the CPU core is at least 450MHZ or faster you can
actually run two or more CPU VPs per core and see increased throughput
from the server. Modern CPUs running at 2-3GHZ can certainly handle
even 3 or more CPU VPs per core. The suggestion to use affinity to
eliminate CPU #0 from use by IDS is not a bad one it guarantees a free
CPU for system maintenance - note that not all machines start CPU
numbering with zero. Sun particularly numbers CPUs depending on what
physical slot the CPU card is inserted into, so you may have to ask your
system administrator to check the lowest CPU number on your systems.

AIO VPs - you need at least 4. If you are using COOKED chunks you
should have between 1 and 1.5 AIO VPs per COOKED chunk plus a few for
the message logging etc., so assuming you mean 167 chunks or 167 single
chunk dbspaces if they are all COOKED devices or filesystem files you
need between 170 and 250 AIO VPs. If all chunks are RAW or you are
using DIRECT_IO (9.40 doesn't support DIRECT_IO but I want to be
complete) you only need between 4 and 6 AIO VPs.

Art S. Kagel

> First, thanks for your time here. You're right it is confusing.
> I ran topas and noticed (Online Virtual CPUs: 8, Online Logical CPUs:
> 16)
> Does that mean 16 physical cpus? I have 167x4gb dbspaces.
>
> Your suggestion then would be:
> VPCLASS cpu,num=15,aff=1-15,noage
> VPCLASS aio,num=167,noage
>
> Thank you.
> Tony
>
> -----Original Message-----
> From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of
> Jonathan Smaby
> Sent: November 28, 2007 12:08 PM
> To: ids@iiug.org
> Subject: Re: CPU Help [10510]
>
> It's kinda of confusing sometimes. How I learned this was:
>
> 7 = Number of Virtual Processors (not necessarily physical CPUs)
> Aio,num=2 is for 2 Asynchronous I/O Virtual Processors.
>
> If you have 16 physical processors I would suggest:
>
> VPCLASS cpu,num=15,aff=1-15,noage
>
> Aff is Affinity, helps tie VP to physical processors (as best I
> understand).
> Notice that aff= isn't starting with CPU #0. I like to leave CPU #0
> alone
> for system and application requests, thus, the remaining CPU's are bound
> to
> Informix virtual processors.
>
> As far as AIO, I like to assign at least 1 virtual CPU per dbspace.
>
> I have a PA-RISC HP System with 8 x 1.0Ghz CPUs and I have 15 dspaces
> (including root-dbs), so my VPCLASS looks like:
>
> VPCLASS cpu,num=7,aff=1-7,noage
> VPCLASS aio,num=15,noage
>
> Just my 2cents.
>
> HTH.
>
> Jonathan B. Smaby
> Pomona College, ITS-AISO Office
>
>
>> From: "Demeis, Tony (MOH)" <Tony.Demeis@ontario.ca>
>> Reply-To: <ids@iiug.org>
>> Date: Wed, 28 Nov 2007 11:33:32 -0500 (EST)
>> To: <ids@iiug.org>
>> Subject: CPU Help [10507]
>>
>> Hi,
>> I need some assistance with CPU vs VPCLASS for a new IDS9.4 server.
>> (1654 MHz CPU, PowerPC_POWER5, 64 bit, 16GB RAM)
>> Nmon shows 16CPUs currently and 16CPUs configured.
>>
>> Onstat -c currently shows:
>> VPCLASS cpu,num=7,noage
>> VPCLASS aio,num=2,noage
>>
>> Does this mean that only 7 CPUs are being used? As this is a dedicated
>>
>
>
>> IDS server, why is it showing 16cpus as being configured and how can I
>>
>
>
>> find out what the configuration is for each cpu. For maximum cpu
>>
> usage,
>
>> what should be the setting for cpu?
>>
>> Thanks,
>> Tony
>>
>>
>>
>>
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Messages In This Thread

• CPU Help
  Demeis, Tony (MOH) -- Wednesday, 28 November 2007, at 11:33 a.m.
  • Re: CPU Help
    Jonathan Smaby -- Wednesday, 28 November 2007, at 12:08 p.m.
    • RE: CPU Help
      Demeis, Tony (MOH) -- Wednesday, 28 November 2007, at 12:22 p.m.
      • Re: CPU Help
        Jonathan Smaby -- Wednesday, 28 November 2007, at 12:32 p.m.
      • Re: CPU Help
        Art S. Kagel (Oninit LLC) -- Wednesday, 28 November 2007, at 3:06 p.m.
  • Re: CPU Help
    RALPH GENTRY -- Wednesday, 28 November 2007, at 12:17 p.m.
    • Re: CPU Help
      Jonathan Smaby -- Wednesday, 28 November 2007, at 12:35 p.m.

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