SINGLE_CPU_VP config query

Posted in 2011

Topics: Performance & Tuning, Platform-Specific Issues, Versions, Editions & End-of-Life

KARL OLIVER — Thu, 24 Mar 2011 00:28:35 — source: IIUG Forums & Mailing Lists

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)

↪ replying to KARL OLIVER

Fernando Nunes — Thu, 24 Mar 2011 00:54:13 — source: IIUG Forums & Mailing Lists

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

↪ replying to KARL OLIVER

Art Kagel — Thu, 24 Mar 2011 03:19:35 — source: IIUG Forums & Mailing Lists

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) > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --bcaec50160c7b4f458049f31f12e

↪ replying to Art Kagel

KARL OLIVER — Fri, 25 Mar 2011 01:08:53 — source: IIUG Forums & Mailing Lists

thanks for information I will try the MULTIPROCESSOR at 0

Glossary

IDS (Informix Dynamic Server)