Re: excessive swapping

[Matt Heler <lkml@lpbproductions.com>]

Can you try using Nick Piggin's np patchset ? 

Matt H.

On Friday 13 August 2004 12:10 am, Florin Andrei wrote:
> On Thu, 2004-08-12 at 23:44, Florin Andrei wrote:
> > On Thu, 2004-08-12 at 23:40, Florin Andrei wrote:
> > > The system is swapping excessively. There's no way the total size of
> > > the applications exceeds the size of RAM. There's plenty of room to
> > > spare, yet 16% of the 530MB of swap is used.
> >
> > Now it's 22% and counting. Way to go. :-(
>
> Now it's 27%. You get the picture.
>
> Anyway, out of the 512MB of RAM, like 390MB are disk cache. No wonder
> that the useful pages are swaped out.
>
> It seems like the kernel believes that the disk cache has some
> miraculous properties w.r.t. the system performance, and desperately
> tries to grow it as much as possible.
> This is wrong religion. The reality is opposite. The system is much
> slower, because applications are thrown out in the swap, then sucked
> back in, which is a very slow process.
>
> The efficiency of increasing the disk cache decreases exponentially with
> size, like any other cache. Then what's the point of sacrificing useful
> memory just to increase some hypothetical "useful" cache?
>
> Even on a server, the same universal laws still apply, the efficiency of
> increasing cache still decreases exponentially. There's still precious
> time wasted when an application is sucked back in from swap, at the
> price of an immeasurably small performance gain due to the disk cache
> being larger.
>
> I'm sorry for rambling, but to me the current swapping policy is so
> blatantly wrong. Besides the space occupied by the apps themselves,
> there's a lot of room to _spare_ - then why swap?