Date: Fri, 30 Aug 1996 22:36:44 -0700 (PDT) From: Doug White <dwhite@gdi.uoregon.edu> To: Scott Blachowicz <scott@statsci.com> Cc: Eric Berenguier <Eric.Berenguier@sycomore.fr>, questions@FreeBSD.ORG Subject: Re: FreeBSD 2.1.0 CRASH! Message-ID: <Pine.BSI.3.94.960830223422.267M-100000@gdi.uoregon.edu> In-Reply-To: <m0uwC7Q-000JTGC@main.statsci.com>
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On Thu, 29 Aug 1996, Scott Blachowicz wrote: > Doug White <dwhite@gdi.uoregon.edu> wrote: > > > Your swap is a bit small for your memory -- suggested is 2xmemory. > > Although running out of swap won't illicit a panic (usually), it would be > > something to consider. > > I've never really quite figured out that recommendation...unless you're > assuming that the system has the "right" amount of RAM to reasonably run all > the applications you want to run on it. In that case, the "2 x RAM" amount > is really an indirect way of saying how much swap you need to run your > applications. The amount of swap space should be more related to how much > stuff you want to have in memory at one time, I would think. I wish I knew the exact history behind it myself :-), but in my experience it's been a good "yardstick", at least for starters. Obviously, you don't have to adhere to it (I could probably get by with 50mb on my 32MB RAM workstation since I'm running X and not using swap), but again it's a starting point. > The size of the recommendation should change depending on whether or not > the swap area is the total virtual address space or just an extension of > the RAM (i.e. > > sizeof(virtual addr space) == sizeof(RAM)+ sizeof(swap) > > instead of just > > sizeof(virtual addr space) == sizeof(swap) FreeBSD uses method #1. It's all the same to the VM system. > ). If on a system doing the latter, 20Mb is definitely not enough swap for > 16Mb of RAM. I don't really know which category FreeBSD falls into (it > could be that any recent OS uses the former method...I don't know). I don't know of any OSs that consider the swap to be total memory available. The three that I know of that use swap other than UNIXen are OS/2, Windows95 and Windows, and they use method #1 too. Doug White | University of Oregon Internet: dwhite@resnet.uoregon.edu | Residence Networking Assistant http://gladstone.uoregon.edu/~dwhite | Computer Science Major
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