Re: Subtle MM bug

[Zlatko Calusic <zlatko@iskon.hr>]

Linus Torvalds <torvalds@transmeta.com> writes:

> On Mon, 8 Jan 2001, Rik van Riel wrote:
> 
> > On Sun, 7 Jan 2001, Wayne Whitney wrote:
> > 
> > > Well, here is a workload that performs worse on 2.4.0 than on 2.2.19pre,
> > 
> > > The typical machine is a dual Intel box with 512MB RAM and 512MB swap.
> > 
> > How does 2.4 perform when you add an extra GB of swap ?
> > 
> > 2.4 keeps dirty pages in the swap cache, so you will need
> > more swap to run the same programs...
> > 
> > Linus: is this something we want to keep or should we give
> > the user the option to run in a mode where swap space is
> > freed when we swap in something non-shared ?
> 
> I'd prefer just documenting it and keeping it. I'd hate to have two fairly
> different modes of behaviour. It's always been the suggested "twice the
> amount of RAM", although there's historically been the "Linux doesn't
> really need that much" that we just killed with 2.4.x.
> 
> If you have 512MB or RAM, you can probably afford another 40GB or so of
> harddisk. They are disgustingly cheap these days.
> 

Yes, but a lot more data on the swap also means degraded performance,
because the disk head has to seek around in the much bigger area. Are
you sure this is all OK?
-- 
Zlatko
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