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SubjectRe: Break 2.4 VM in five easy steps
Richard Gooch wrote:
> Daniel Phillips writes:
> > On Wednesday 06 June 2001 10:54, Sean Hunter wrote:
> >
> > > > Did you try to put twice as much swap as you have RAM ? (e.g. add a
> > > > 512M swapfile to your box)
> > > > This is what Linus recommended for 2.4 (swap = 2 * RAM), saying
> > > > that anything less won't do any good: 2.4 overallocates swap even
> > > > if it doesn't use it all. So in your case you just have enough swap
> > > > to map your RAM, and nothing to really swap your apps.
> > >
> > > For large memory boxes, this is ridiculous. Should I have 8GB of
> > > swap?
> Sure. It's cheap. If you don't mind slumming it, go and buy a 20 GB
> IDE drive for US$65. I know RAM has gotten a lot cheaper lately (US$66
> for a 512 MiB PC133 DIMM), but it's still far more expensive. If you
> can afford 4 GiB of RAM, you can definately afford 8 GiB of swap.

For me, the problem is not the money. If I have a system that needs
4GB of RAM, it is highly unlikely that I would ever want to be running
this machine with 8GB of swap active. However, I may be willing to
tollerate 1GB of swapping before paging to disk slowed things down
too much. This is the exact scenario I had when dealing with a large
Sun machine running Oracle & some other stuff. Oracle is dedicated large
amounts of RAM, but if I wanted to run a quick, memory intensive program
too, (and at the moment performance isn't all that big of a deal), then
using some swap is OK.

So, I too cast my vote for the 2*RAM requiment to be odious and in
need of fixing!! It could be a suggestion, but I would consider that
if not following the suggestion caused more than 10% slowdown, then
things are still broken, and optimally, it should work like the 2.2
does (in other words, I don't notice, and don't particularly care
how much swap per RAM I need, just how much total RAM-like-stuff I need.)


Ben Greear <> <>
President of Candela Technologies Inc
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