Re: [9fans] Plan 9

[Wladimir Mutel <mwg@fluffy.isd.dp.ua>]

Alexander Viro <viro@math.psu.edu> wrote:

>> > What do people think about per-process directory hierarchies?  I've
>> > asked the question about four times now, and sadly, nobody in this
>> > happy collaborative environment has anything to say.
>>
>>       Nice thing. Linux is to borrow it :>

> Not likely, unless you can show a damn good reasons why it's a good idea.

	I am not sure the reasons are 'damn', I just thought that linux kernel
	patches on this topic should have some future.

>> > To repeat: Plan 9 has a nifty idea of making mount tables per-process,
>> > and as a result gets huge benefits across the board.  But why stop
>> > there?  Why should not *all* links (instead of just some) be a

>>       Linux should also borrow 'fileserver' concept.
>>       Nice to have it instead of VFS-layer. And to make userspace
>>       fileserver-processes instead of kernel VFS modules.

> Huh?  What in your opinion VFS is and how could userland filesystems
> replace it?  BTW, Plan 9 _does_ have VFS equivalent - code that deals
> with channels, mounts, etc.

	VFS is a kernel module interface to support different filesystems. It
	describes protocol similar (to some degree) to 9P. Plan9 has some
	in-kernel modules (device drivers) working by 9P, but it supports FAT
	and EXT2 filesystems by fileservers that are processes. Similar
	approach is used in Hurd; strong decomposition of traditionally-kernel
	fucnctionality into processes can be found in QNX. I do not think they
	all were wrong in their design decisions. The more functionality is
	possible to express as separate process, the simpler is to control it.
	Linux kernel itself has more and more "kernel processes" from version
	to version. Here is what i have in 2.4.12 -
	[keventd] [ksoftirqd_CPU0] [kswapd] [bdflush] [kupdated]

	So, that is overall cause of my words written in comp.os.plan9 above.