Re: [RFC] VM: I have a dream...

From: Bernd Petrovitsch
Date: Wed Jan 25 2006 - 04:23:22 EST


On Mon, 2006-01-23 at 23:08 -0300, Horst von Brand wrote:
[...]
> Good rule of thumb: If you run into swap, add RAM. Swap is /extremely/ slow
> memory, however fast you make it go. RAM is not expensive anymore...

- Except on laptops where you usually can't add *any* RAM. And if you
can, it is *much much* more expensive than on "normal" PCs.
- Except if you - for whatever reason - have to throw out smaller RAMs
to get larger (and much more expensive) RAMs into it.
- Except (as someone else mentioned) you have already equipped your main
board to the max.

> > You have roughly 2 GB of dynamic address-space avaliable to each
> > task (stuff that's not the kernel and not the runtime libraries).
>
> Right. But your average task is far from that size, and most of it resides
> in shared libraries and (perhaps shared) executables, and is perhaps even
> COW shared with other tasks.
>
> > You can easily have 500 tasks,
>
> Even thousands.
>
> > even RedHat out-of-the-box creates
> > about 60 tasks. That's 1,000 GB of potential swap-space required
> > to support this.

And after login (on XFCE + a few standard tools in my case) > 200.

> But you really never do. That is the point.

ACK. X, evolution and Mozilla family (to name standard apps) are the
exceptions to this rule.

Bermd
--
Firmix Software GmbH http://www.firmix.at/
mobil: +43 664 4416156 fax: +43 1 7890849-55
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