Re: Clusterwide pids

[Lars Marowsky-Bree <lmb@suse.de>]

On 2001-07-11T13:27:35,
   "Albert D. Cahalan" <acahalan@cs.uml.edu> said:

> > This leaves us with the chicken and egg problem - how do you
> > boot a node which is - at the time of boot - unable to contact
> > the cluster?
> You don't. It is a mistake to design for this perversion.

Uh. A node not being able to join the cluster is a perfectly reasonable
exception, and you want it to boot so that you can fix it over the network. It
makes sense not to start any cluster services, that is true.

> Do you, or do you not want a shared PID space? Make up your
> mind about this. You don't run an SMP system as multiple
> uniprocessor systems, then suddenly decide that you want SMP!

Refer to the CPU hotplug features in recent 2.4 kernels ;-)

Besides, if your implementation decides that you do not want to provide this
"intermediate" step between shared / not-shared PID space, that is fine.

> > IMHO, a node should be able to have "local" processes (node id
> > part of the CPID = 0). Only after it joined the cluster once
> > (and thus was assigned a node id) should processes which need
> > a valid CPID be started.
> Now what am I supposed to do with the "ps" program I wrote?
> Invisible processes? Nope, not at all OK. This is crap too:
> 
>   PID TTY          TIME CMD
>     1 ?        00:00:03 init
>     1 ?        00:00:03 init
>     1 ?        00:00:03 init
>     1 ?        00:00:03 init

You won't see this.

init is almost guaranteed to be a "local" process, and thus not visible to
other nodes.

Sincerely,
    Lars Marowsky-Brée <lmb@suse.de>

-- 
Perfection is our goal, excellence will be tolerated. -- J. Yahl


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