Re: Future Linux on Bistable Storage

["Daniel J Blueman" <daniel.blueman@gmail.com>]

On 2 Jun, 14:40, Rick van Rein <rick@groengemak.nl> wrote:
> Hello,
>
> Future generations of Linux are likely to run on machines with non-volatile
> memories based on bistable technologies.  This will save the energy of DRAM
> refresh cycles and avoid the mechanical problems related to hard disks.  The
> result is probably a computer with no distinction between disk and RAM.
>
> Such computer architectures can conserve a lot of energy, as it is very
> simple to suspend and resume them: no data loss means no time needed to
> resume the system -- except perhaps for I/O initialisation.  Conserving
> energy means (1) having more fun|hours per kg of batteries, and (2) saving
> the planet.
>
> I wonder inhowfar Linux is (already) capable of dealing with such hardware.
> Several core concepts suddenly become meaningless if disk and RAM are merged
> into one storage device:
>  * swapping out data
>  * lazy loading of programs from disk to RAM
>  * buffering disk blocks
>  * mapping and unmapping disk onto RAM
[snip]

Perhaps one of the more key stepping stones here is execution in place
(XIP) support, which at present works for a particular combination of
embedded architecture, block device and filesystem. Maybe that's the
wrong way of looking at it, and we should consider XIP-for-ramdisk
(rather than ROM/flash).

Anyway, from a mmap() perspective, we'd be logically merging the
filesystem and pagecache layers and losing a layer of physical
indirection.
-- 
Daniel J Blueman