smorgan@pixus.unm.edu (Scott Morgan) (09/14/89)
We have a Symmetry S27 with 6 CPUs that's used for general class instruction (compile/link/go users with a few math/stats packages thrown in on the side). We've recently run into problems with interactive response (we average somewhere around twenty to forty concurrent users). From looking at `vmstat` output, we're apparently swapping a fair amount. So, it looks like we're in need of memory. We currently have 8Mbytes (most likely shocking to the sys admin's reading this newsgroup). Anyway, I was wondering what other types of memory/processor/job mixes folks are running. Please send me email, and I'll summarize to the net as appropriate. BTW, we called our local Sequent sales rep to ask what their opinion was of our problem. The standard vendor response was given (but appropriate in this case, I suspect): "Buy more <insert_vendor_name> memory...." The sales rep said that they recommend somewhere between 4 and 8 Mbytes per processor. Is that a common configuration? Anyway get away with running less? Under what job mix? - Scott - ------------------------------------------------------------------------ -------- Scott Morgan [SM137] Phone: (505) 277-8137 Systems Programmer / Technical Leader UNM CIRT/ACS 2701 Campus Blvd. NE Albuquerque, NM 87131 Internet: smorgan@ariel.unm.edu BITnet: smorgan@unmb[.bitnet] --------------------------------------------------------------------------- "I need to find a good quote...." Scott Morgan (July 6, 1989)
jackg@sequent.UUCP (Jack Griffith) (09/26/89)
In article <509@ariel.unm.edu> smorgan@ariel.unm.edu writes: > > We have a Symmetry S27 with 6 CPUs that's used for general class >instruction (compile/link/go users with a few math/stats packages >thrown in on the side). We've recently run into problems with >interactive response (we average somewhere around twenty to forty >concurrent users). From looking at `vmstat` output, we're apparently >swapping a fair amount. > > So, it looks like we're in need of memory. We currently have 8Mbytes When swapping it is useful to take a look at your "ps" output RSS column which is the Resident Set Size in memory of the processes running. It may be that processes are exceeding what you really require them to have for RSS. vmtune(8) can be used to dial down the maxRS (maximum resident set size) to top off the maximum RSS to allow enough memory for all of the processes. For example, if you had 5 processes whose RSS was at 3.5 Mbytes, then you would begin to swap and performance would degrade (with only 8Mbytes of memory). Now if you were to dial down the maxRS to 1Mbyte (using vmtune -R 1000), then each process could only grow to 1Mbyte and you would still have memory left. Paging MAY increase (if the processes are always paging into pages not in the resident set, then you may not even be increasing the page fault frequency (pff) of the process), but the response time is more reasonable. ________________________________________________________________________________ Jack Griffith Customer Service Technical Support Engineer Specialist Sequent Computer Systems uunet!sequent!jackg (800) 854-9969 ________________________________________________________________________________