RE: 2.2.16 Alpha: "Fix SMP rescheduling with lock held"

["Greg Lindahl" <glindahl hpti com>]

> > That depends on the detail. Are you running PVM in daemon mode or using
> > direct routing?

Hint:

In daemon mode, PVM uses UDP, and of course that means it has to split big
messages. If you use direct routing, which almost all PVM programs use
because it's faster, processes open direct tcp connections and don't go
through the daemon.

Since you are using the daemon, there's no excuse for the Linux kernel to be
freezing for that long.

> It would depend on exactly what those messages are trying to
> say. I would expect pvmd to go into a hard read() loop of some
> sort collecting bytes of the data until it gets the complete
> chunk transferred.

In order to avoid deadlocks with general communication patterns, most
libraries do more sophisticated things.

-- g