[Spread-users] Multicast and Performance issues

[Yair Amir]

Hi,

I am not sure what the problem with your network is.
Just for reference, on Fast Ethernet with a local subnet
with ok machines (some Pentium III) Spread should do better than 50Mbits/sec.
On our similar network we clocked it around 75Mbits/sec or so.

I am not sure what the B in your 333kB means (bits or bytes) but
either way you are at least 25 times slower than expected.

	Cheers,

	:) Yair.

David Turland wrote:

> Hi,
> 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
> 
> 
> 
> 
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