[Spread-users] Multicast and Performance issues

Theo Schlossnagle jesus at omniti.com
Fri Mar 15 16:44:45 EST 2002


Sounds like a hardware problem to me.  What OS are you using?  What 
cards are you using?  What drivers for those cards?  What switch and 
what is the running config on that switch?

On Friday, March 15, 2002, at 04:03 PM, David Turland wrote:
> Currently using Spread in earnest and trying to reach the plateau of 
> 1MB/sec
> multicast to 36  nodes(Athlon 1.2G,Fast ethernet, switched, local 
> subnet).
> (This is the performance I was getting using LAM/MPI and a tree-based
> broadcast -  If I can't achieve this then I will tolerate the hit of
> incorporating failover support using LAM/MPI)
>
>
> so far topping out at 333kB/sec; whether I choose RELIABLE or 
> UNRELIABLE.
>
> I feel Iam not configuring Mlticast correctly as this value is the same
> whether I use a unicast rather than Multicast address in spread.conf
>
> Spread_Segment  192.168.42.255:4803 {
> master 192.168.42.91
>  .
> .
>  .
>
>                          vs.
>
> Spread_Segment  225.0.1.1:4803 {
> master 192.168.42.91
>  .
> .
>
>  .
> I really know nothing about multicast and feel there is something more 
> I need
> to be doing than choosing 'arbitrary' multicast addresses in the 
> spread.conf
>
> incidentally,there is an entry in the /etc/rc.local file pertaining to
> multicast:
>
> # Setup the default multicast route
> /sbin/route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
>
> I think I need some more info before I spproach our sys admin guys...
>
>
> Currently the benchmark I am running uisngs two threads, one for  
> sending and
> receiving with synchronisation (cv) between the sending and receiving 
> threads
> so that the acks from (one or all ; makes little differnece) of the 
> receivers
> are received before the next sending iteration takes place. If I omit 
> this
> lock step then the session is closed arbitrarily, I presume because 
> excessive
> mesages are stacked up in a buffer.
>
>
> Interestingly, I played with max packet size, up to 1MB, but with my 
> current,
> (non-multicast?) configuration I saw no performance changes.
>
>
> I love the concept of spread, there are bits of it I am taking for 
> granted
> which will take an age in LAM/MPI or RMT or RMTP to implement but I 
> need to
> reach the magic 1MB/sec, or beyond
>
>
>
>
> _______________________________________________
> Spread-users mailing list
> Spread-users at lists.spread.org
> http://lists.spread.org/mailman/listinfo/spread-users
>
>
--
Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone:  +1 301 776 6376       Fax:  +1 410 880 4879
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