Re: LINUX is obsolete Linux Inside
[Prev][Next][Index][Thread]

Re: LINUX is obsolete

 In article <TYTSO.92Jan31164013@SOS.mit.edu> tytso@athena.mit.edu (Theodore Y. Ts'o) writes:
 > This is not necessarily the case; I think you're painting a much more
 > black and white view of the universe than necessarily exists.  I refer
 > you to such papers as Brent Welsh's (welch@parc.xerox.com) "The
 > Filsystem Belongs in the Kernel" paper, where in he argues that the
 > filesystem is a mature enough abstraction that it should live in the
 > kernel, not outside of it as it would in a strict microkernel design.
 
 What does "a mature enough abstraction" mean, here? Things don't move
 into the kernel simply because they're now considered safe and stable
 enough, but because they're too inefficient when they're outside it or
 they lose functionality by being outside it, and there's no easy fix.
 
 The Amiga operating system certainly benefits from having a file system
 outside the kernel. There are dozens of file systems, many of them written
 by hobbyists, available. Ideas like "assigned paths" can be played with
 in the file system without breaking stuff. All these file systems have a
 common interface and so look to the application as part of the operating
 system, but just because something is on the other side of the API doesn't
 mean it is, or belongs, in the kernel.
 
 > There also several people who have been concerned about the speed of
 > OSF/1 Mach when compared with monolithic systems; in particular, the
 > nubmer of context switches required to handle network traffic, and
 > networked filesystems in particular.
 
 If this is because the networking was moved out of the kernel, I consider
 it a price well worth paying. Having networking code in the kernel is the
 source of many subtle bugs in networks. Just for something that bit us,
 what happens if you need to get to the upper level driver before you can
 acknowledge a packet, but the process that you need to run is hung up in
 the tty driver waiting for a ^Q?
 
 Something *I* would have expected to find in the kernel before now, yet
 isn't, is windowing systems. With a microkernel (and the associated lower
 *cost* of a context switch) you can get much of the advantages of a kernel
 window system without paying the cost in complexity.
 -- 
 -- Peter da Silva,  Ferranti International Controls Corporation
 -- Sugar Land, TX  77487-5012;  +1 713 274 5180
 -- "Have you hugged your wolf today?"