On Wed, 6 Feb 2008, Reuti wrote:
Just an idea to check: PVM can also be started without rsh/ssh between the
machines. You have to copy and paste some things from here to there and back
and can startup all daemons this way by hand (page 30 in the PVM book). Maybe
this works - just to narrow the cause.
I'll look into this, thanks, although the daemon IS started -- the block
it is somewhere after that. But it is well worth trying anyway.
I also wonder about ports and WAP interactions. I've got my WAP
configured (AFAICT) as an internal switch, not really as a router. As
in my laptop get DCHP service from my linux server, not the WAP, which
is flat to broadcasts, has no port filtering on the internal network
etc.
I even ran tcpdump on the problem last time it happened -- maybe I
should try it again.
rgb
-- Reuti
I suspect a race condition, probably caused by using raw UDP with some
assumption of latency during the handshake. The one way I can think of
that the two connections differ is in their latency -- even the
bandwidth of wireless is every bit as great as 10B2 networks I've run
PVM on in years past (on proportionally slower CPUs, of course). If the
master or slave send out an acknowledgement packet either before the
window where the other can receive it or after it has grown bored and
stopped listening, it might fail to properly bind or something. It
seems like it would be a bug, not a feature, but if I were feeling
infinitely masochistic and were to wander down into Other People's
Source (ouch!) to try to debug this, that's what I'd look for first.
Any PVM developers still on list? Any comments from them?
rgb
Just a thought,
-bill
On Feb 6, 2008, at 10:40 AM, Robert G. Brown wrote:
Anybody on list have any idea why PVM fails to add hosts over a wireless
link? I've now tried this over multiple distro version and at least one
PVM update, and it just doesn't work. Works fine over a wire, fails on
wireless, and as far as I know wire and wireless are both "identical"
at the kernel interface layer so that any e.g. socket one might open is
absolutely ecumenical about what the underlying hardware is (good old
ISO/OSI layering, right?).
--
Robert G. Brown Phone(cell): 1-919-280-8443
Duke University Physics Dept, Box 90305
Durham, N.C. 27708-0305
Web: http://www.phy.duke.edu/~rgb
Book of Lilith Website: http://www.phy.duke.edu/~rgb/Lilith/Lilith.php
Lulu Bookstore: http://stores.lulu.com/store.php?fAcctID=877977
_______________________________________________
Beowulf mailing list, Beowulf@beowulf.org
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
--
Robert G. Brown Phone(cell): 1-919-280-8443
Duke University Physics Dept, Box 90305
Durham, N.C. 27708-0305
Web: http://www.phy.duke.edu/~rgb
Book of Lilith Website: http://www.phy.duke.edu/~rgb/Lilith/Lilith.php
Lulu Bookstore: http://stores.lulu.com/store.php?fAcctID=877977
_______________________________________________
Beowulf mailing list, Beowulf@beowulf.org
To change your subscription (digest mode or unsubscribe) visit
http://www.beowulf.org/mailman/listinfo/beowulf
