On Tue, 2 Jul 2002, dfox wrote: > > No, I wouldn't say it's all that ridiculous. Of course these things are > > relative: what you do with your machines may not require you to ever > > It's not ridiculous either, unless you're thinking of emailing it > somewhere :).
:D > > > drop into swap. Kernels around 2.4.10 and earlier had serious problems > > with memory, and requiring a few extra meg of memory would not > > I'm not sure I agree, but that's a minor point. Surely some of these > kernels had wonky use of swap, but AFAIK all linux kernels viewed swap > as additive, rather than as 'backup store' on BSD systems. BSD is why > most older people quote the 1.5 X as much as RAM, or even 2X swap for > what you have in RAM rule. Of course, recent kernels have been getting > more well behaved; I seem to remember that this was just an anomaly of > some 2.4.x kernels, though. I did some looking in the kernel archives and found the following: Kernel versions from 2.3.something to 2.4.10pre9aa1 required *at minimum* the same amount of swap space as physical memory. This version was when the Arcangeli patches appeared and (from his release note) provide "swap+ram of available virtual memory". Link: http://kt.zork.net/kernel-traffic/kt20011001_135.html#2 It does seem to have improved recently, though there are no firm benchmarks on either side yet. Hmm...this could be an interesting little project to stress out the vm. We'd need a little program that would grab memory and not let it go, maybe mark each page dirty so that it stays in the working set... I found some example code in one of Moshe Bar's columns (Linux Kernel Pillow Talk). > > > My favorite swap related anecdote (true story - this actualy happened:) > A friend of mine (who is a fairly light Linux user, had migrated from > a Sinclair with 128k or so of RAM to a 386 with 4 megs. He thought 4 > megs was more room than he'd ever need. He didn't set up a swap partition > at all - and then look what happened when he tried to run 2 copies of > emacs at the same time. The kernel took *46 minutes* just to respond to > the ctrl-x ctrl-c commands to quit one of those instances.) And of course, > this was all in-memory thrashing since there wasn't any swapping to disk. Pretty, isn't it? BTW, have you played with the overcommit settings in /proc with a swapless system?
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