[Spread-users] spread performance looks not very good for me

John Schultz jschultz at commedia.cnds.jhu.edu
Tue Dec 9 20:41:48 EST 2003

On Tue, 9 Dec 2003 wei_hu at agilent.com wrote:

> Can anyone answer performance difference between one daemon and two
> daemons in one subnet?
One daemon alone should always perform very well. This is because it will
never have data msg losses and therefore (non-safe) msgs will be
immediately deliverable.  I believe even a single daemon still sends 
all of its traffic on the network and must receive its own token back 
before sending again.  Your speed of 80Mbps is reasonable (if a little 
slow) for a single daemon -- the network should be the limiting factor in 
this case.

A two daemon network should not see such a dramatic drop-off in throughput
it should also nearly achieve 80Mbps.  More than likely, your broadcasting
is not working (either your network is messed up or the interfaces on the
machines are messed up).  In this case, the daemons can fall back to use
unicast to the requesting daemon (I believe this only works for two daemon
memberships).  However this causes lots of overhead: the initial broadcast
attempt of the messages, an additional circulation of the token and then a
unicast of each message.

Even that though doesn't completely explain your order of magnitude drop
off in throughput.

Have you tried configurations with more machines?  I believe if your 
broadcast address isn't working properly they should have problems passing 
any msgs beyond two daemons.

> 1.Two machines, both have the same spread config as following:
> Spread_Segment {
>         redhook
>         mendecino
> }

Your configuration looks fine as long as you have a /24 network and your
netmasks ( are configured properly on all the machines and
the switches/routers interconnecting them.

> 2. on "redhook", run
> On the spread terminal, i always saw "Num of groups: 0".  It is normal?
On an initial startup, yes, as no clients should be connected yet so there
can be no groups.

John Lane Schultz
Spread Concepts LLC
Phn: 443 838 2200

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