Re: [patch 00/20] VM pageout scalability improvements

[Rik van Riel]

On Mon, 24 Dec 2007 04:29:36 +0530
Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
> Rik van Riel wrote:

> > In the real world, users with large JVMs on their servers, which
> > sometimes go a little into swap, can trigger this system.  All of
> > the CPUs end up scanning the active list, and all pages have the
> > referenced bit set.  Even if the system eventually recovers, it
> > might as well have been dead.
> > 
> > Going into swap a little should only take a little bit of time.
> 
> Very fascinating, so we need to scale better with larger memory.
> I suspect part of the answer will lie with using large/huge pages.

Linus vetoed going to a larger soft page size, with good reason.

Just look at how much the 64kB page size on PPC64 sucks for most
workloads - it works for PPC64 because people buy PPC64 monster
systems for the kinds of monster workloads that work well with a
large page size, but it definately isn't general purpose.
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