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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
The point is that we have an entire OS subsystem that probably isn't needed at all for a lot of use cases. Who wouldn't want to get rid of that complexity.
Preparing for nonvolatile RAM
Posted May 25, 2012 3:48 UTC (Fri) by viro (subscriber, #7872)
What do you think 'ls' stands for? That's right, "list segments". In a directory segment, that is. As for the supposed complexity... Take a look at the amount of code in fs/ramfs someday. Especially if you leave no-MMU side of things alone...
Posted May 29, 2012 20:40 UTC (Tue) by daglwn (subscriber, #65432)
There is a lot of complex code that could be dumped if everything lived in a random-access memory. Device drivers alone would be a huge savings.
Posted May 29, 2012 21:33 UTC (Tue) by paulj (subscriber, #341)
Posted May 30, 2012 1:36 UTC (Wed) by daglwn (subscriber, #65432)
Posted May 30, 2012 4:43 UTC (Wed) by dlang (✭ supporter ✭, #313)
However, they have always run into the stumbling block that it's just impractical to deal with all hunks of data in a flat namespace. Directories are EVIL, but nobody has make anything else work even one tenth as well
Also, just keeping everything in ram falls apart as soon as you want someone else to access it (or you loose the device, or the device gets destroyed, or ...)
Many of the people pushing back have been though this "eliminate filesystems" experiment before and have the scars to show for it. Listen and learn (then go try and build something to prove them wrong :-)
Posted May 31, 2012 19:35 UTC (Thu) by timka.org (guest, #53366)
Posted May 30, 2012 4:52 UTC (Wed) by paulj (subscriber, #341)
Posted May 30, 2012 14:54 UTC (Wed) by daglwn (subscriber, #65432)
I think the discussion is pretty pointless now...
Posted May 30, 2012 0:11 UTC (Wed) by Trelane (subscriber, #56877)
Because not all memory is the same, let alone the pipe over which we get it.
How would you use a hypothetical storage medium that had 1EB of storage but you could only access it at 128kbps?
Posted May 30, 2012 1:37 UTC (Wed) by daglwn (subscriber, #65432)
The filesystem is the abstraction and that abstraction has certain costs. Changing the abstraction doesn't imply we immediately forget everything we know.
Posted May 30, 2012 6:53 UTC (Wed) by viro (subscriber, #7872)
One more time, slowly:
* fs/ramfs/inode.c does *not* optimise for rotating storage, what with having nothing whatsoever to do with any storage.
* it does *not* optimise for disc buffering, what with having no backing storage, disc or otherwise
* file cache (page cache, really) is just a mechanism for finding a page by offset in file. In case of object living entirely in RAM, that's exactly what you need to work with that object. Unless you want your objects to be contiguous in RAM, that is - great idea, that, for e.g. 800Kb text file. Or a 22Mb PDF document.
* Device drivers have nothing whatsoever to do with aforementioned ramfs.
* You have demonstrated just what is wrong with "visionaries". You keep making profound sounds without stopping to check whether they have anything to do with reality. Other than that of your bowel movements, that is.
As for being deliberately dense... I wouldn't have dared - any attempt to fake being dense would be simply pathetic next to the geniune article of that magnitude.
Posted May 30, 2012 14:55 UTC (Wed) by daglwn (subscriber, #65432)
Posted May 30, 2012 21:25 UTC (Wed) by Cyberax (✭ supporter ✭, #52523)
Don't know about you, but after Al Viro's post I went and checked VFS source code - and he's entirely correct.
Posted May 30, 2012 21:59 UTC (Wed) by daglwn (subscriber, #65432)
I never claimed to be a "visionary." I'm far, far from that. The idea isn't even original, people have talked about it for years. It just strikes me that it makes a lot of sense given system architecture trends. Outright dismissal accompanied by foul language, holier-than-thou attitudes and outright insults says much more about Al than it does me.
Al definitely lost a notch or too on my respect ladder and that's a pity because I've generally enjoyed reading his posts/articles.
Posted May 31, 2012 1:29 UTC (Thu) by bronson (subscriber, #4806)
I'm no linguist but anybody who disagrees is a dweeb. :)
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