job migration

Jag agrajag at linuxpower.org
Fri Mar 9 20:57:40 PST 2001


On Fri, 09 Mar 2001, Daniel Ridge wrote:

> On Thu, 8 Mar 2001, Jag wrote:
> 
> > On Thu, 08 Mar 2001, Daniel Ridge wrote:
> 
> > > Why not just use fork()/bproc_execmove() ? You don't need then to have any
> > > of the binaries installed remotely. You can (if you're clever) even
> > > manage to get the dynamic link step to happen on the frontend. 
> > 
> > I didn't do that because I need to be able to redirect
> > stdin/stdout/stderr.  BProc can't forward open file descriptors, so I
> > have to rfork, open the new files, use the dup2 magic to redirect stdin
> > and stdout, then exec() the process.  See my recent post on the bproc
> > list if you actually want to see some code for that.
> 
> bpsh knows how to do this already. Would it be more helpful if I made bpsh
> available as libbpsh?

I looked over bpsh, but couldn't find much that it does in the way of IO
redirection except forwarding stdin and stdout over the network.
Would libbpsh do something like bproc_execmove(), except you also give
it fd's for stdin, stdout, and stderr, where the fd's you give it are
fd's on the master node that the exec()'ed process uses transparently
over the network?  If so, then I think its something that would be quite
useful for any kind of program that wants to propagate jobs to the slave
nodes.

Out of curiosity, what overhead is there for this?  Is it just an extra
process on the master node used for processing all the IO requests?


Jag
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