Re: SMP/cc Cluster description

Jeff Dike
2001-12-07T03:38:16Z

akeys@post.cis.smu.edu said:
> it seemed to me that you could easily simulate what you want with
> lots of UML's talking to each other. I think you would need to create
> some kind of device that uses a file or a shared memory segment as
> the cluster's memory.

Yeah, there is already support for mapping in a random file and using that
as UML memory, so that would be used for the cluster interconnect for any
cluster emulations you wanted to run with UML.

> Actually, I think that (shared memory) is how
> Jeff had intended on implementing SMP in UML anyway.

No, at least not any shared memory that's not already there. UML uses a
host process for each UML process, and UML kernel data and text are
shared between all these host processes. SMP just means having more than
one host process runnable at a time. Each runnable process on the host
is a virtual processor.

> At this point I
> don't think UML supports SMP though I know of at least one person who
> was attempting it.

It doesn't yet. Someone is (or was), but I haven't heard a peep from him in
at least a month. So this is starting to look like another little project
which got quickly going but just as quickly abandoned.

Jeff