From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: <31ab45d5d167967b7f2d8295682c11fa@quanstro.net> References: <268C756C-4B08-4266-8D7E-1247A45F8577@gmail.com> <31ab45d5d167967b7f2d8295682c11fa@quanstro.net> Date: Tue, 22 Sep 2009 07:39:09 -0700 Message-ID: <3e1162e60909220739t61cff0e3t8eea92b6e8d26641@mail.gmail.com> From: David Leimbach To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: multipart/alternative; boundary=000e0cd5bb4ead6a8704742b8f88 Subject: Re: [9fans] linux stats in last year from linuxcon Topicbox-Message-UUID: 74895eca-ead5-11e9-9d60-3106f5b1d025 --000e0cd5bb4ead6a8704742b8f88 Content-Type: text/plain; charset=ISO-8859-1 On Mon, Sep 21, 2009 at 7:33 PM, erik quanstrom wrote: > > > "We're getting bloated and huge. Yes, it's a problem," said Torvalds." > > > > So may be Tanenbaum was right, after all, there's a reason we make > > things modular. > > rob, presotto, ken and phil did not agree with tanenbaum's > ideas about modular kernels. > > this was a direct response to ast many years ago. it was > hard to dig up when i did so in 2006. perhaps someone > has a better link: > > - Microkernels are the way to go > False unless your only goal is to get papers published. > Plan 9's kernel is a fraction of the size of any microkernel > we know and offers more functionality and comparable > or often better performance. > > This does not mean they were saying microkernels can't be done well :-). At least I hope not, because there's a few counterexamples out there. L4 based systems are quite impressive, though their idea of a microkernel is a bit more like an advanced hypervisor, but more for something along the lines of paravirtualization. QNX is another good example of a microkernel that works quite well in practice. If by microkernel you mean Mach, and hopefully no one does anymore, then you're pretty much dead on ;-). Even the latest versions of Minix really aren't too shabby and still microkernel based. (small memory footprint, decent functionality, lots of Unix stuff work on it, and they have an interesting choice of compilers.) Are these systems more complex to reason about though? Probably :-). But when you've only got 7 system calls (per the original L4 specifications I've read over) you don't really have a lot to debug. Just gotta make sure you chose the correct primitives to compose all the software you need to write on the system. I think, in that sense, Plan 9 and some microkernels are pretty similar. Dave > - erik > > --000e0cd5bb4ead6a8704742b8f88 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

On Mon, Sep 21, 2009 at 7:33 PM, erik qu= anstrom <quan= stro@quanstro.net> wrote:
> > "We're getting bloated and huge. Yes, = it's a problem," said Torvalds."
>
> So may be Tanenbaum was right, after all, there's a reason we make=
> things modular.

rob, presotto, ken and phil did not agree with tanenbaum's
ideas about modular kernels.

this was a direct response to ast many years ago. =A0it was
hard to dig up when i did so in 2006. =A0perhaps someone
has a better link:

=A0 - Microkernels are the way to go
=A0 =A0 =A0 =A0False unless your only goal is to get papers published.
=A0 =A0 =A0 =A0Plan 9's kernel is a fraction of the size of any microk= ernel
=A0 =A0 =A0 =A0we know and offers more functionality and comparable
=A0 =A0 =A0 =A0or often better performance.


This do= es not mean they were saying microkernels can't be done well :-). =A0At= least I hope not, because there's a few counterexamples out there.

L4 based systems are quite impressive, though their ide= a of a microkernel is a bit more like an advanced hypervisor, but more for = something along the lines of paravirtualization. =A0QNX is another good exa= mple of a microkernel that works quite well in practice.

If by microkernel you mean Mach, and hopefully no one d= oes anymore, then you're pretty much dead on ;-).

<= div>Even the latest versions of Minix really aren't too shabby and stil= l microkernel based. =A0(small memory footprint, decent functionality, lots= of Unix stuff work on it, and they have an interesting choice of compilers= .)

Are these systems more complex to reason about though? = =A0 Probably :-). =A0But when you've only got 7 system calls (per the o= riginal L4 specifications I've read over) you don't really have a l= ot to debug. =A0Just gotta make sure you chose the correct primitives to co= mpose all the software you need to write on the system.

I think, in that sense, Plan 9 and some microkernels ar= e pretty similar.

Dave
=A0
- erik


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