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

From: Al Boldi
Date: Thu Feb 02 2006 - 13:59:34 EST


Alan Cox wrote:
> On Maw, 2006-01-31 at 18:56 +0300, Al Boldi wrote:
> > So with 64bits widely available now, and to let Linux spread its wings
> > and really fly, how could tmpfs merged w/ swap be tweaked to provide
> > direct mapped access into this linear address space?
>
> Why bother. You can already create a private large file and mmap it if
> you want to do this, and you will get better performance than being
> smeared around swap with everyone else.
>
> Currently swap means your data is mixed in with other stuff. Swap could
> do preallocation of each vma when running in limited overcommit modes
> and it would run a lot faster if you did but you would pay a lot in
> flexibility and efficiency, as well as needing a lot more swap.
>
> Far better to let applications wanting to work this way do it
> themselves. Just mmap and the cache balancing and pager will do the rest
> for you.

So w/ 1GB RAM, no swap, and 1TB disk mmap'd, could this mmap'd space be added
to the total memory available to the OS, as is done w/ swap?

And if that's possible, why not replace swap w/ mmap'd disk-space?

Thanks!

--
Al

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