gt1111a@prism.gatech.EDU (Vincent Fox) (06/06/91)
We have an S81 with 10 CPU's. Sometimes when answering the phone or other distractions arise, I leave a little program running called top. It shows the top jobs, the load average, etc. One thing I have noticed is that sometimes top will show that it's running 30-40% idle even with 200+ people on. Yet the keyboard response is slow and clunky. Since the CPU is mostly idle, one must assume the bottleneck is somewhere between my keyboard and the CPU. Since it's an ethernet connection, it's nothing to do with a slow serial port chip or anything like that. Could be DYNIX I suppose. Probably is come to think of it. Any ideas? -- Vincent Fox (That's Mr. Bucko to you)|Georgia Tech, the only place where Friday Georgia Tech, Atlanta GA |is only two working days away from Monday. SR-71: gt1111a@prism.gatech.edu | -- Uttered by David Sonnier during Pony Express:...!gatech!prism!gt1111a| CS3602 lab 5/10/1991 ~ 1730 EDT
spaf@cs.purdue.EDU (Gene Spafford) (06/06/91)
Vincent notes that sometimes with 200+ people on, the CPU is 30%-40% idle, and keyboard response is slow. He concludes it is an I/O problem. That is very possibly correct, but i may not be the Ethernet as he suggests. Memory-starved machines behave the same way. If the CPU is spending a lot of time moving user pages in and out of memory, processes will be blocked while awaiting their pages, and will not appear to be using much of the CPU. Vincent's attempt to type something makes his job active and causes it to fight for the page pool, too, thus giving the "jerky" behavior he notices. Using "vmstat" to observe page faults would be a good idea. It will reveal if this is a problem or not. The cure is not faster I/O, but more memory. -- Gene Spafford NSF/Purdue/U of Florida Software Engineering Research Center, Dept. of Computer Sciences, Purdue University, W. Lafayette IN 47907-1398 Internet: spaf@cs.purdue.edu phone: (317) 494-7825