Hi Adrian,
On 4/29/07, Adrian Knoth wrote:
On Sun, Apr 29, 2007 at 10:18:01AM -0400, George Bosilca wrote:
[snip]
BTW: How does multi TCP BTL works? I see num_links, but I wonder if
kernel channel bonding would achieve the same results...
Unfortunately, kernel channel bonding is very unlikely to achieve the
same results as Open MPI's striping with multi TCP BTL.
Here is a relevant snippet of the documentation for kernel channel bonding:
balance-rr: This mode is the only mode that will permit a single
TCP/IP connection to stripe traffic across multiple
interfaces. It is therefore the only mode that will allow a
single TCP/IP stream to utilize more than one interface's
worth of throughput. This comes at a cost, however: the
striping often results in peer systems receiving packets out
of order, causing TCP/IP's congestion control system to kick
in, often by retransmitting segments.
The Open MPI way avoids this packet reordering problem, since
any individual TCP stream is carried by only a single NIC at either
end of the transmission. Since Open MPI splits the MPI traffic
across multiple TCP streams, additional throughput is possible
without the low-level packet reordering problem.
If you really want to know more about this, I could go on at length,
but I'll spare the rest of the readers on the mailing list for now.
--
Tim Mattox - http://homepage.mac.com/tmattox/
tmat...@gmail.com || timat...@open-mpi.org
I'm a bright... http://www.the-brights.net/
