SINGLE_CPU_VP config query
Karl Oliver asked why SINGLE_CPU_VP is recommended for one CPU VP on a multi-CPU HP-UX system with IDS 11.50.FC6. Fernando Nunes said the number of CPUs is irrelevant; it only tells the engine just one CPU VP is configured, avoiding synchronization. Art Kagel agreed: only use it if you never run more than one CPU VP, since it removes some latching and locking. Karl said he would try it.
Auto-generated by Claude from the posts below — may be imperfect; read the full thread.
HPUX HP-UX wuasp132 B.11.23 IBM Informix Dynamic Server Version 11.50.FC6 I am curiuos why the following recommendation would be made to set following option to 1 cpu vp. Epecially if running on multi cpu system Is there less overhead with it being set to 0 ? SINGLE_CPU_VP - Optimizes performance if IDS runs with # only one CPU VP. Acceptable values are: # 0 multiple CPU VPs # Any nonzero value (optimize for one CPU VP)
On Thu, Mar 24, 2011 at 12:28 AM, KARL OLIVER <karl.oliver@maf.govt.nz>wrote: > HPUX > HP-UX wuasp132 B.11.23 > IBM Informix Dynamic Server Version 11.50.FC6 > I am curiuos why the following recommendation would be made to set > following option to 1 cpu vp. Epecially if running on multi cpu system > Is there less overhead with it being set to 0 ? > > SINGLE_CPU_VP - Optimizes performance if IDS runs with > # only one CPU VP. Acceptable values are: > # 0 multiple CPU VPs > # Any nonzero value (optimize for one CPU VP) > > > http://publib.boulder.ibm.com/infocenter/idshelp/v115/topic/com.ibm.adref.doc/id s_adr_0161.htm I think the number of cpus in the system is irrelevant for this parameter. What it tells the engine is that only one CPU VP is setup. As such several synchronization mechanisms are not necessary and you can gain some performance with that. -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently... --0015174c3bded2f4f1049f2fe9a1
If you are only planning to NEVER have more than one CPU VP (so you will
configure VPCLASS cpu,num=1 AND you will never run "onmode -p +1 cpu") then
setting SINGLE_CPU_VP to 1 (OK non-zero) will allow the engine to eliminate
some latching and locking of memory structures that would be necessary to
prevent memory corruption if there are more than one CPU VP. If you can set
this, and really are using a single cpu vp, the engine's overhead is reduced
somewhat, yes.
Art
Art S. Kagel
Advanced DataTools (www.advancedatatools.com)
Blog: http://informix-myview.blogspot.com/
Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Advanced DataTools, the IIUG, nor any other
organization with which I am associated either explicitly, implicitly, or by
inference. Neither do those opinions reflect those of other individuals
affiliated with any entity with which I am affiliated nor those of the
entities themselves.
On Wed, Mar 23, 2011 at 8:28 PM, KARL OLIVER <karl.oliver@maf.govt.nz>wrote:
> HPUX
> HP-UX wuasp132 B.11.23
> IBM Informix Dynamic Server Version 11.50.FC6
> I am curiuos why the following recommendation would be made to set
> following option to 1 cpu vp. Epecially if running on multi cpu system
> Is there less overhead with it being set to 0 ?
>
> SINGLE_CPU_VP - Optimizes performance if IDS runs with
> # only one CPU VP. Acceptable values are:
> # 0 multiple CPU VPs
> # Any nonzero value (optimize for one CPU VP)
>
>
>
>
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thanks for information I will try the MULTIPROCESSOR at 0