lkml.org 
[lkml]   [1998]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Remote fork() and Parallel programming
On Tue, 16 Jun 1998, Larry McVoy wrote:

> : I realized that I might someday want to run my app on a 100 node cluster
> : insted of just my SMP system... MPI seemed to be a better (performance
> : wise) solution to cluster programming, although it did require non-trivial
> : effort to program using it at first.
>
> Agreed on both points; though I claim that it is good for your brain to fit
> your computation into messages, it tends to make some other nice things
> happen in the design of your code.

Yes, I can agree with that. I gained a deeper understanding of what data
is needed where by using MPI insted of DSM.

> : It seemed wiser to write my software for MPI and deal with the
> : difficulties and it being non-optimum on my smp system. (Although I've
> : never tested it, I'm sure that shared memory on a smp system is *MUCH*
> : faster then MPI)...
>
> Actually, only if you don't do anything to the MPI libraries. I.e., they
> are doing networking through the loopback device.

Yes. Though I seem to recall that the Linux loopback device does jump over
a fair portion of the stack.

> SGI took the libs, gutted 'em, leaving just the interfaces, and tuned them
> especially for SMP machines (yeah, they can still call out to the networking
> ones when they need to).

I posted yesturday to your cluster list about doing this on Linux.. I
would very much like to see this.. Perhaps it would be wise to first
optimize MPI for SMP systems, then optimize MPI for Linux clusters.

> They even did some VM hacking such that they could map another process'
> address space so that a send() turned into
>
> find the process associated with the destination
> make we've already mapped the destination
> bcopy()
>
> It was damn close to no more than the bcopy() cost.

Sounds good here..


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu

\
 
 \ /
  Last update: 2005-03-22 13:43    [W:0.054 / U:0.280 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site