> I don't think process migration is such a bad idea, I just think that the
> costs don't out weigh the benefits. I'm not saying that it can't be done,
> I'm saying that it shouldn't be done, especially not at the expense of
> normal OS performance, reliability, and maintainablity (adding code to
> the kernel is mutually exclusive with all of those in almost all cases).
I'm going to put as little code on the kernel as possible. I won't
transform Linux into a migration-dependent OS. The kernel will help on the
migration, but a Linux system without the "migration daemon" won't migrate
anything, it will just work as any other independent system. A Linux
system with the migration daemon (migd for short), but without the policy
daemon won't migrate processes at will, unless someone tells migd that it
should migrate something.
It's a very modular thing, each part doing only it's own job, and I'd
like to get as little overhead as possible on the kernel, so that other
things don't get too slow.
> So here's a question: if it worked and was useful, why has that facility
> not made it into any sucessful commercial or free operating systems? Was
> it ahead of its time or is there some inherent reason?
How would you go about migrating a Windows95 process, when it's so close
to the hardware? What use is there for migration on a net of Word loaders?
People that use Windows95 just don't need migration. People who run some
Unix sometimes do, as usually they do some number crunching and other
CPU bound ativities that could take advantage of it.
I just received a mail telling that AIX for PS/2 had migration some years
ago.
> The point is that yes, you can do it. But that is an academic point,
> not anything that is actually useful. Not in my experience. I'm happy
> to be proven wrong, but I'm unhappy with letting people go down a
> proven rathole.
That's why I'm doing it, I'm graduating in Computer Science. I started
this thread to get some comments and suggestions about it, not to ask
people if they wanted migration on _their_ Linuxes. If you don't want,
don't use it, period. Heck, I don't even dream about getting it on
mainstream Linux!
Hope this "you can't do this to Linux" stuff ends. If people get
interested on my work, I'll distribute patches on my pages, one day.
[]
Fabio
( Fabio Olive Leite leitinho@akira.ucpel.tche.br )
( Computing Science Student http://akira.ucpel.tche.br/~leitinho/ )
( )
( LOADLIN.EXE: The best Windows95 application. [Debian GNU/Linux] )