Re: Serious performance issues

Bill, How many tli poll threads are you running? If a tli poll thread runs on a cpuvp it will generate semops and busy waits like you see on vp 7. Look at the NETTYPE parameter. BTW. I know you are a Sequent/Informix user from previous posts. What revs are you running and how is it going? Crashes? Performance? Stephen Berg At 10:53 AM 6/3/99 -0500, Bill Weaver wrote: >In the past few weeks, we went through a major upgrade of our database where we completely >redesigned a large portion of the database structure, migrated the data, and updated the >applications. Since that period, we've had serious performance problems. We went from a system >that averaged 30-40% cpu idle time to one that stays 0-5% idle (more often at 0% idle during the >day). I have to believe the problem is inefficencies in the new database structure as that is >what changed. However, I'm at a total loss as to how to find where these inefficencies are! >I/O is more evenly spread out on this new system than on the old so it isn't an I/O problem >(which is also supported by the sudden increase in cpu utilization). The applications (4GL >code) are the same applications, the only changes made to them were to support the new structure >- no major logic changes were made - yet they themselves perform worse under the new system. > >Anybody have any advice as to how to track down what's causing this and eliminate it? Any areas >that I need to be looking at? One addition we made to this new structure that wasn't in the old >was that we added referrential integrity utilizing foreign keys. Can the additional overhead >from referrential integrity checks cause or contribute to our performance woes? I've considered >eliminating the foreign keys (one key table is referenced by almost every other table in the >system for example) and replacing them with regular indexes. Would this help? > >One interesting thing I've noticed is that even during periods of 0% idle time, one of my cpuvps >is still performing busy waits and semops. There is stuff sitting on the ready queue (onstat -g >rea) but for some reason it isn't picking it up. And, it is always the same processor that has >these busy waits/semops. The other 5 cpuvps have 0 in busy waits and semops so they are staying >fulling utilized (I have an 8 processor system - 6 are dedicated and affinitied to a production >instance of Informix, 1 to a development instance of Informix, and the last one is left free for >OS - it actually is the first physical processor). Following is the output of onstat -g sch: > > vp pid class semops busy waits spins/wait > 1 22836 cpu 0 0 0 > 2 22937 adm 0 0 0 > 3 22938 cpu 0 0 0 > 4 22939 cpu 0 0 0 > 5 22940 cpu 0 0 0 > 6 22941 cpu 0 0 0 > 7 22942 cpu 6923 8395 9116 > 8 22944 lio 0 0 0 > 9 22945 pio 0 0 0 > 10 22946 aio 0 0 0 > 11 22947 msc 2004 0 0 > 12 22956 aio 0 0 0 > 13 22957 tli 18 27 786 > >-------------------------------------------------------- >Name: Bill Weaver >E-mail: Bill Weaver <billw@fscorp.com> >Date: 06/03/99 >Time: 10:53:46 > >(Retrospectively realizes there is no future in hindsight) >-------------------------------------------------------- > >