Re: Recommended swap for 2.4.x.

[Rik van Riel]

On Tue, 30 Jan 2001 [e-mail] wrote:
> On Tue, Jan 30, 2001 at 09:48:33AM -0200, Rik van Riel wrote:
> > It has. We now leave dirty pages swapcached, which means that
> > for certain workloads Linux 2.4 eats up much more swap space
> > than Linux 2.2.
> 
> Ah.. thanks for the clarification.  Is this duplication "hard"
> or "soft"?  i.e. under low-memory conditions, do these
> duplicated pages actually reduce the hard limit of VM available,
> or just imply that using that last bit of memory will entail
> greater paging overhead (because it has to do more cleanup)?

At the moment there is no way to reclaim the swap space if
the page is shared, and for non-shared pages we haven't
implemented a way to reclaim swap space.

While reclaiming swap space when you run out is pretty
trivial to do, Linus doesn't seem to like the idea all
that much and Disk Space Is Cheap(tm) so it's not very
high on my list of things to do.

> Does this mean that having a swap partition less than or equal
> to RAM is now effectively pointless?

If you're swapping heavily, yes. If most of your programs
fit in memory and you're hardly using swap, nothing changes.

regards,

Rik
--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

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