Re: NET or CPU VP Class : confusing NETTYPE recommendations

Hi Sean, I am also puzzled by this. The recommendations for NETTYPE are confusing. I have read almost as many different recommendations as there are possibilities. Art Kagel : TechNote Article 1998 - Volume 8 - Issue 3 : "Tuning Informix Dynamic Server and Your System for Optimum Performance" : - shared memory connections always on CPU VPs - tli connections always on NET VPs - use as many poll threads for shm as you have CPU VPs SUN Informix specialist : article "Tuning Informix for OLTP Workloads" - for high transaction rate OLTP, use NET VPs for polling - using CPU VPs causes continues switching from processing queries to handling network operations (bad for processor cache) - bind CPU VPs to physical processors (poll thread will use others) Informix 7.3 Performance Guide page 3-18 and following : => not all that clear to me SAP R/3 OSS Note 41360 : - CPU VPs for tli connections in case of different machines for the SAP R/3 application instances - NET VPs for shm connections in case there is little activity (user connections) on the database server - Is it better to have poll threads running on CPU VPs or NET VPs ? - Is it better to have a few poll threads supporting many connections each or a lot of poll threads ? - When choosing CPU VPs for the most used connections, will this interfer with all other work that the CPU VPs already must handle (KAIO is used) ? - Informix books and course notes state that you can not use CPU VPs for more than one protocol, but apparently it does work. We have been using CPU VPs for shared memory connections and for TLI connections for a very long time. Is it dangerous/inefficient to use CPU VPs for both protocols ? - Should I look at NETTYPE settings in conjunction with processor affinity (setting the AFF_ ONCONFIG parameters or calling the pbind command) ? - Does anyone have suggestions for our environment ? We have a db server (SUN) with 18 processors and a small SAP R/3 (central) instance on it and 8 SAP R/3 application servers accessing that db server (tli) ? We have 50 TLI connections per SAP application server (although this represents more users - SAP uses "workprocesses", something similar to virtual processors). Kind regards, Mario PS : We also had an instance crash recently. Informix recommended to stop using shared memory connections, and use the safer TLI connections instead. In our case, this was not a big problem as most of the work was already using TLI connections, so the impact on global performance was minimal. ______________________________ Reply Separator _________________________________ Subject: NET or CPU VP Class Author: "Sean Kelsey" <seank@teepee.demon.co.uk> at internet Date: 20/4/99 11:19 Good morning Informixers. We have been going through a series of conversations with Informix technical support and I thought I would like to test all you DBA's out there as to what the general consensus is regarding the VP class that the soctcp poll thread should run on. We are using IDS 7.30.FC6 on HP-UX 11.x. We were having problems with earlier releases of the engine ( 7.24.UC7 ) where we were getting Assert Failures due to the soctcppoll thread crashing. Informix Tech Support told us that it was a know bug and we should adopt to one of the following:- 1. Reduce the number of poll threads that run 2. Increase the number of users that each poll thread services 3. change the class of VP from CPU to NET ( 4. Upgrade, of course ) As you can see from the below NETTYPE settings, we opted for a mixture of 1 & 2 but we are occasionally getting the same assert failure. NETTYPE ipcshm,1,50,NET NETTYPE soctcp,2,300,CPU # This is the new one # NETTYPE soctcp,3,200,CPU # This was the old setting NETTYPE sqlmux,,, So, okay, if we change the VP class to NET, will this not slow things down significantly for all user connections ? Can anyone point out what benefits (if any) changing the VP class will give us and which ones do you recommend... TIA as always Sean