On Friday May 27 2005 9:50 am, Sean Davis wrote: > On Fri, May 27, 2005 at 10:43:11AM -0400, Carl Fink wrote: > > On Fri, May 27, 2005 at 07:00:56AM -0400, Sean Davis wrote: > > > *: Linux LOVES to swap. I swap all the time on my 1.8ghz Athlon > > > XP with 1GB ram. However, my NetBSD machine with the same > > > amount of ram running at the same frequency NEVER swaps, due to > > > the ability to tune the VM, and the better VM (UVM) in general. > > > The NetBSD server almost always has at least twice if not three > > > times as much going on (+ KDE3.4) than the Linux machine. Yet > > > still never swaps or lags. Wish I could say that for Debian > > > Woody, but I can't. > > > > Linux swaps aggressively, even when unnecessary in the short term > > on purpose, so RAM containing the swapped data or executable is > > available if a new task arises. If the swapped stuff is called > > for, it's used from RAM and no time is lost. > > no time is lost... you have infinite-transfer-speed zero-latency > drives, or what? I can't be the only one who's noticed that when > machines start swapping, they start getting slower. Or the only one > to connect the two, for that matter. He's talking about the swap *out* there. Swapping in is where you see the slowdown. Linux tries to swap out as pre-emptively and aggressively as possible so if you need more cache or a program needs more space in-core. > If there is enough RAM for the current workload, there is no reason > to swap. Period. Swapping when it's not needed is a ridiculous > waste of CPU time and disk I/O. If I understand your argument > correctly, an accurate analogy would be leaving your car running > 24/7 just so that you don't have to start it the next time you want > to drive somewhere. Would you do that? no. I would leave it on 24/7 if it were an easy to physically secure, 12vDC device with a relatively constant power supply. You know, like a hard drive? 8:o) Mechanical devices of any type *DO NOT* like to start moving from a standstill, it's one of the most physically stressfull things a machine can do. -- Paul Johnson Email and Instant Messenger (Jabber): baloo@ursine.ca http://ursine.ca/~baloo/
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