High OnLine server load

Subject: Data General Informix Online server load. --------------------------------------------------- I am working with a Data General Aviion 8000, which is setup to be an Informix Online server (Online 5.00). In normal daytime with up to 500 backend processes. 5 to 10 will be heavy batch jobs and the rest more normal online applications. Under these circumstances the cpu may stay on 0% idle and a load between 5 and 9. The responsetime is then very bad. At other times when only 2 batch jobs are running, the response time for online applications will be ok. I have tryed a couple of times to renice cpu heavy jobs to lowest possible priority and after some time, the response time seems to get better. This could be done automatic with a home made 'nice- scheduler', but other solutions might be possible. The unix kernel has a FIFO to schedule the jobs, and as far as I can understand this could give the heavy batch jobs a big piece of the cpu power. It is possible to set a flag 'cf_vp_do_lifo' to change the scheduler to use a LIFO, which as I see it, could help the online applications and give the heavy batch jobs a smaller piece of the cpu's. My question is now, have you any experience with LIFO scheduling on a unix machine ? (If DG as an Online server it would be perfect.) If the scheduler policy shifts to LIFO could it then be expected, that online jobs, which fights for the same resources might get into problems, if new jobs gets first to the cpu's ? Do you have any input that might help me ? Thanks from: ----------------------------------------------------------------- Databaseadministrator Poul Pedersen Kuwait Petroleum (Danmark) A/S Hummeltoftevej 49 Mail: pp@q8.dk 2830 Virum Voice: +45 45 98 45 94 Denmark Fax: +45 42 85 14 18 -----------------------------------------------------------------