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Re: re[2]: Clusterwide pids
El Jueves 12 Julio 2001 21:15, escribiste:
> > Let us summarize a bit:
> > -most people agrees we need unique CPID even if the process is something
> > we know is not going to migrate as init.
> > -that CPID will be node number + local pid
>
> process creation node number + process creation uniquifier
that's what i wanted to say
>
> > - We don't want to recompile userspace apps so we do our own system
> > calls, which maybe :
> > * getcpid to get the ¿64bits? with the standard getpid returning the low
> > 32 bits of the CPID
> > * getnode(pid) with 0 if process if local , nonzero otherwise.
>
> I certainly don't agree with this. pid's are 32 bits so having both node
> number and uniquifier is quite feasible (have been doing it for a dozen
> years). This way it is all transparent, which, in the case of SSI
> clustering, is key.
I think we are talking about the same, i gave 2 posibilities , it seems you
think the second is right . if so i agree with you.
We have to think the our changes in the kernel are better if they are less
intrusive and i think changing pid size is not the way , we just add a
structure in the task struct where one of the fields is the node number.
More fields must be discussed as soon as we decide something about this
issue.
> > Then we have a question left: ¿How we manage to get unique CPIDs ?
> > What number node a machine must have, ¿read it from /etc? ¿read it a la
> > HDLC?
>
> The issue, as I mentioned earlier, is when/how does a node get a node
> number. The DLCP idea is interesting. Another option is something in lilo
> or ram disk. Specifying it must be in /etc is bad for those of us with a
> single root. I like the idea of a "cluster" system call. One of the
> subcommands of it would be set your node number. Different cluster
> implementations could gather that number from different places.
even with a single root you're having diferent configurations for every
machine (ip, inittab ...) so just add a new file with the node id. If you are
managing all the cluster nodes, you can just give every node a different
number, the problem comes when you just want to connect your laptop to the
cluster and you have no idea about what node numbers are being used.
--
Jordi
Student of Spain
Linux-cluster: generic cluster infrastructure for Linux
Archive: http://mail.nl.linux.org/linux-cluster/