Without some sort of performance tool to actually measure what had been going on at the time, it's nearly impossible to say. Some applications will benefit greatly from being multi-threaded, others not. The issue may not have been multi-tasking related. It could have been simple single-thread instruction execution speed, which a second processor would not have helped. (And by the way, adding a second processor only gets you about 80% more usable cycles, due to the SMP effect.) It could have been that MySQL wasn't configured properly for a shared environment. It could have been darn near anything. Again, without data to look at, anything would be sheer speculation, just as I've been indulging in above.
Mark Post -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Jon Brock Sent: Monday, October 23, 2006 4:41 PM To: LINUX-390@VM.MARIST.EDU Subject: Re: zLinux experience Actually, this leads me to a related question I have been wanting to ask: is anyone aware of an analysis of the difference between a single-IFL vs a multi-IFL system under VM? We have an application we wanted to bring up under VM/Linux, but when we tried it we had great difficulty with it and eventually backed it off. It struck me as peculiar that the image we were using as a database server (running MySQL) took sometimes 80% of our single IFL. There shouldn't have been enough database activity to eat that much CPU. Our CIO chewed off the head of one of the local IBM guys (unfairly, IMHO) over the whole debacle. It seems to me that having a multiprocessor system could have made a difference for us, outside of the obvious doubling of CPU cycles. (The aforenamed now headless IBM guy had arranged for us to get a loan of another IFL, but the doctors here were inflicting too much pain on our CIO for him to be game for the delay it would have meant.) Would having multiple IFLs have eased our pain in regard to processing a client-server app? Seems like it would. Thanks, Jon ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
