Re: Informix hogging CPU

The multithreading architecture of DSA uses the virtual processors scheme in which we have the CPU virtual processors (they are called CPU VPs because they run the cpu intensive threads and they are supossed to make non-blocking system calls). There's allways a low priority problem related with CPU VPs in Unix OSes thas use traditional scheduling schemes (like HP-UX 9.04). As the traditional schemes tend to decrease the priority of the CPU intensive processes and the CPU VPs allways consume their entire CPU quantum, the CPU VPs have allways a very low priority in production environments. HP-UX 10.X OS designers gave to software developers a solution to this problem that was the one used in the implementation of DSA 7.X for HP-UX 10.X : a system call a process make to tell the kernel not to decrease its priority. Informix On-Line DSA 7.X for HP-UX 10.X uses this system call when the parameter NOAGE is on. I think DSA makes the system call at initialization time when oninit processes wait for some system calls to complete (at that moment their priority is pretty good because they don't have consumed their entire CPU quantum and the OS doesnt't have lowed their priority). If the CPU VPs processes have a fixed high priority, the other processes with lower priorities won't run until the oninit processes go to sleep or until the OS assigns them a higher priority. If nobody except the oninit processes cand do anything (the telnet server processes, shells, etc), the problem is like the OS is not giving CPU to anyone else than the oninit processes (because the other processes have lower priorities than the oninit, and the OS doesn't decrease the priority of the oninit processes because they have made the system call i metioned before because of the value of the NOAGE parameter). So, turn off the NOAGE parameter.!!!! Fernando Alvarez falvarez@inea.com.ar Mike Matthews wrote: > I am running Informix Online Server version 7.1 on D250, one cpu, HPUX > 10.10. When Informix gets hit with an SQL statement doing a few joins an a > 35,000 record database, the system just crawls while the statement > executes (takes about 5 minutes). No one can login and if you are logged > in, you get a response to hitting ENTER about 40 seconds after hitting it. > TOP shows oninit processes running with a priority of -16 and oninit > processes using about 90% of the CPU. I don't see any obvious errors in > the ONCONFIG file. Has anyone seen anything like this and is there any way > of configuring Informix to use less CPU? > > TIA > > Mike Matthews > mmatt@halcyon.com