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Preparing for nonvolatile RAMPreparing for nonvolatile RAMPosted May 25, 2012 3:03 UTC (Fri) by daglwn (subscriber, #65432)In reply to: Preparing for nonvolatile RAM by iabervon Parent article: Preparing for nonvolatile RAM
And this is all because we think the filesystem abstraction is the only way to go. NVRAM certainly could replace disks on some devices and really, what's the difference between storing data on disk in a filesystem and storing on disk in the form of pages?
There are many other, better ways to do IPC.
I don't think a filesystem-less Linux would work that well - the concept is too ingrained into the kernel. But starting from scratch? I would seriously consider not providing a filesystem at all.
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Preparing for nonvolatile RAM Posted May 25, 2012 5:10 UTC (Fri) by mrons (subscriber, #1751) [Link]
There have been operating systems that have removed the filesystem abstraction. I recall reading about the Monads system in the 80's:
http://www.jlkeedy.net/research-highlights.html
Don't know how far they got with an actual implementation though.
Preparing for nonvolatile RAM Posted May 31, 2012 19:56 UTC (Thu) by timka.org (guest, #53366) [Link] There's also Phantom OS. Never tried it myself but it's still active and looks interesting.
Preparing for nonvolatile RAM Posted May 25, 2012 8:52 UTC (Fri) by dgm (subscriber, #49227) [Link]
It would not work. There are two use cases that the pointer/page combination doesn't cover, namely: removable storage and named data. Both are very important, so a system that doesn't support them will not be very useful.
And as Viro said above, the moment you add a name->page mapping... voilà! the filesystem is back.
Preparing for nonvolatile RAM Posted May 29, 2012 20:45 UTC (Tue) by daglwn (subscriber, #65432) [Link]
I guess I'm not following what's so special about "named data." Ultimately it's a mapping from a user-readable handle to a machine-readable handle. And no, such a mapping does not have to look like a filesystem at all. We don't necessarily even want a concept of directories as such, for example.
I'll grant that removable media presents a challenge. But with The Cloud(TM) these days, do we even need it? I'm talking about certain common use cases. Certainly we need it for lots of things but I don't think everyone in the world needs it.
Even so, I wonder if page migration could be adapted to support removable storage. Page out on one system, page back in on another.
Just thinking blue sky here, I'm not an expert on any of this.
Preparing for nonvolatile RAM Posted Jun 1, 2012 1:07 UTC (Fri) by kevinm (guest, #69913) [Link]
What people are trying unsuccessfully to point out is that *all* the "filesystem abstraction" is is a mapping from a hierarchical name and offset into a memory address. That's all it is.
About that only thing you can change that about that and still have a mapping from names to memory is to change what the names look like. Maybe you don't want them to be hierarchical - maybe you want them to be flat, or multidimensional instead of single-dimensional. But there doesn't seem to be a good reason why changing how the names look is in any way related to NVM.
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