CPU idles

I have an Informix server running IDS 9.40.UC2 on AIX 5.2. The server is having issue where the CPU goes completely idle, even though there are seven or more queries running against the system. The system has 1 GB of data and 2 CPUs, but they wanted the configuration file set up for 2 CPUs instead of single processor. Has anyone else had an issue like this, where the CPU will work for a while and then completely go idle, and then get throttled again? Should we have this configuration file configured for a single CPU? Any thoughts would be appreciated. Thanks. ______________________ Keith Schleicher DBA IT Infrastructure Shared Services VNU, Inc. Phone: 920-405-7955 NETS: 8-270-7955 email: kschleicher@acnielsen.com

Hi, First: it is possible to set the NUMCPUVPS parameter to a higher value than actual processors in the system. This sometimes leads to better response times. (when you encounter idle time on your CPU (using sar) and the number of active threads is not decreasing). We once had a system with 4 CPU and used NUMCPUVPS = 8 for optimum performance. But you could have another problem, which is not possible to analyze on the information you gave. Possibly the server is waiting for I/O or doing a checkpoint, maybe you have a PDQ set which uses all your active threads, or the disk layout is not optimal an you have a bottleneck there. Other reasons might be the problem like locks, latch waits/mutex waits. Try querying the database with onstat -g ath/act/sch/iov. This might give you a hint what the real problem is. Hope this gives you a hint, Marcus -----Original Message----- From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On Behalf Of Schleicher, Keith M. Sent: Wednesday, November 22, 2006 8:46 PM To: ids@iiug.org Subject: CPU idles [7868] I have an Informix server running IDS 9.40.UC2 on AIX 5.2. The server is having issue where the CPU goes completely idle, even though there are seven or more queries running against the system. The system has 1 GB of data and 2 CPUs, but they wanted the configuration file set up for 2 CPUs instead of single processor. Has anyone else had an issue like this, where the CPU will work for a while and then completely go idle, and then get throttled again? Should we have this configuration file configured for a single CPU? Any thoughts would be appreciated. Thanks. ______________________ Keith Schleicher DBA IT Infrastructure Shared Services VNU, Inc. Phone: 920-405-7955 NETS: 8-270-7955 email: kschleicher@acnielsen.com **************************************************************************** *** Forum Note: Use "Reply" to post a response in the discussion forum.

Can you do onstat or is the engine hung? what does get throttled again mean? starts working again? is the engine online? or hung in chk point? awaiting logs to be flushed? out of space? locks? etc? Ken In a message dated 11/22/06 14:57:11 Eastern Standard Time, KSchleicher@ACNielsen.com writes: I have an Informix server running IDS 9.40.UC2 on AIX 5.2. The server is having issue where the CPU goes completely idle, even though there are seven or more queries running against the system. The system has 1 GB of data and 2 CPUs, but they wanted the configuration file set up for 2 CPUs instead of single processor. Has anyone else had an issue like this, where the CPU will work for a while and then completely go idle, and then get throttled again? Should we have this configuration file configured for a single CPU? Any thoughts would be appreciated. Thanks. ______________________ Keith Schleicher DBA IT Infrastructure Shared Services VNU, Inc. Phone: 920-405-7955 NETS: 8-270-7955 email: kschleicher@acnielsen.com ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum. --20519149-fe38-467b-8963-e5c48feffcf8

> Hi, > > First: it is possible to set the NUMCPUVPS parameter to a > higher value than actual processors in the system. This > sometimes leads to better response times. (when you encounter > idle time on your CPU (using sar) and the number of active > threads is not decreasing). We once had a system with 4 CPU > and used NUMCPUVPS = 8 for optimum performance. > > But you could have another problem, which is not possible to > analyze on the information you gave. > Possibly the server is waiting for I/O or doing a checkpoint, > maybe you have a PDQ set which uses all your active threads, > or the disk layout is not optimal an you have a bottleneck > there. Other reasons might be the problem like locks, latch > waits/mutex waits. > Try querying the database with onstat -g ath/act/sch/iov. > This might give you a hint what the real problem is. > > Hope this gives you a hint, > Iostat and vmstats would be handy as well Paul Watson Tel: +44 1414161772 Mob: +44 7818003457 Web: www.oninit.com GO FURTHER with DB2 GET THERE FASTER with Informix. Attend IDUG 2007 San Jose, North America May 6-10, 2007 Visit http://www.iiug.org/conf for more information.

Hi Keith, Do you have nmon installed? http://www-128.ibm.com/developerworks/aix/library/au-analyze_aix/ Are you paging? Do you have blocked processes? Do you have i/o waits? What does your onstat -p look like? DT > -----Original Message----- > From: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] On > Behalf Of Schleicher, Keith M. > Sent: Wednesday, November 22, 2006 1:46 PM > To: ids@iiug.org > Subject: CPU idles [7868] > > > I have an Informix server running IDS 9.40.UC2 on AIX 5.2. > The server is having issue where the CPU goes completely > idle, even though there are seven or more queries running > against the system. The system has 1 GB of data and 2 CPUs, > but they wanted the configuration file set up for > 2 CPUs instead of single processor. > > Has anyone else had an issue like this, where the CPU will > work for a while and then completely go idle, and then get > throttled again? Should we have this configuration file > configured for a single CPU? > > Any thoughts would be appreciated. Thanks. > ______________________ > Keith Schleicher > DBA > IT Infrastructure Shared Services > VNU, Inc. > Phone: 920-405-7955 > NETS: 8-270-7955 > email: kschleicher@acnielsen.com > > > ************************************************************** > ***************** > Forum Note: Use "Reply" to post a response in the discussion forum. > > >