On Fri, Apr 18, 2003 at 02:10:33AM +0100, Tim Bradshaw wrote: Right. Yeah, I know. So in SunOS 4.x, the buffer cache still existed but it was used only for inodes and directories, not for file pages. There were problems for sure with the new VM system. But remember, it was the first system that gave you mmap() and it really worked. I remember sales calls (I was engineering but I could speak "customer") against HP where they claimed they had mmap but all that meant was that they malloc-ed the memory and copied it. So if you had N processes mapping the same file it cost N*P in memory. SunOS got it right. And we fixed it as we learned what was broken. I'm the guy that made sure we didn't dirty 100% of memory from one process doing dd if=/dev/zero of=XXX There were a lot of other tuning efforts going on at the same time. Forgive me for getting all maudlin on you, but at the time, Sun was the *only* place that was doing real OS work. Nobody else came close. I fought to get in there and then I walked around for three years saying "I'd work here for free if I had more money" before I realized that saying that had a bad effect on my salary :-) It really was a fantastic time to be at Sun. They were doing anything that was cool in OS, everyone else was just playing catchup, to this day I have not seen anything like it. Look around today, is Microsoft doing anything cool? Sure, they understand UI and they do a fantastic job at it, but in the OS area they can't begin to compare with Sun. Microsoft OS engineers at their best are nowhere near as good as Sun OS engineers at their worst. It was one hell of an education. It's not clear to me where a new engineer could go today to get a better education. -- --- Larry McVoy lm at bitmover.com http://www.bitmover.com/lm