[Spread-users] Spread Performance

[Ryan Caudy]

[Hope this doesn't come out garbled, but I forgot to CC to the list 
first time.]

My comments are inlined below.

Good luck,
Ryan

William Isley wrote:

 > Hi Spread Group,
 >
 > I plan to use spread to reliably multicast Gigabytes of files to 40+ 
machines. I have tried several configurations, and with only 5 clients 
receiving files (rebuilt from messages sent over Spread), the best data 
throughput I can achieve is 3 MB/sec. I am required to achieve at least 
6 MB/sec.
 >

What is your network environment?  I'll assume a LAN with 100 Mbps ethernet.

 > I have tried running the Spread Daemon on a separate server, on the 
message sender, and a message receiver. I get the best performance with 
the Spread Daemon running on the message receiver. I am using the SAFE 
message transport type, but have tried the UNRELIABLE message transport 
type with negligable performance gain.
 >

I'd recommend that you run Spread daemons on all of the hosts that have 
Spread clients (sender and all receivers in your system).  The idea here 
is to maximize the amount of data that is transferred over your network 
as multicast/broadcast.  Otherwise, you end up with the same unicast 
data going over the network several times.  Multicast is only done 
between daemons in the same segment.

I don't know for sure what your application's semantics are, but it 
sounds to me like you don't need SAFE messages.  For a one-to-many 
system like you describe, FIFO should be sufficient.  The application 
should be easier to develop with service type FIFO (or higher) than 
RELIABLE or UNRELIABLE.

 > I have tried scheduling Spread to run with Realtime scheduling. The 
performance gain was negligable. I am running all of this software on 
Windows.
 >

I wouldn't be surprised if you didn't get all the performance you want 
on Windows, although giving it high priority as you've described should 
certainly help.  Be careful to make sure that the clients get plenty of 
CPU time also, so that the sender can send fast enough, and so that the 
receivers can keep up.

 > I tried running the Spread Daemon on a dual Xeon processor machine. 
The result is that the Spread clients loose there connection under heavy 
load. The other machines in the configuration single 1GHz processor 
machines.
 >

Again, I'd recommend that you use many Spread daemons, not just one. You 
may need to tweak the flow control a bit, but I think you'll be ok with 
a network like I described.  Keep in mind that if your sender outpaces 
your receivers, Spread will eventually disconnect them.

 > I need to squeeze more out of Spread than 3 MB/sec. The website 
advertises 8 MB/sec. What can I do to better this performance? Are there 
any changes I can make to the Spread.conf file that will increase the 
performance? Is it possible to run multiple Spread Daemons? How to I 
configure this system if this is an option and what is the benefit?
 >

It is not only possible, but almost always desirable to run multiple 
Spread daemons.  To do so, the only major change is to the 
Spread_Segment section of the spread.conf file.  Basically, instead of 
using the configuration for a single daemon (usually just a daemon on 
localhost using the localhost broadcast address), you use a 
configuration more like
Spread_Segment xxx.yyy.zzz.255:4803 {
   hostname1  xxx.yyy.zzz.11
   hostname2  xxx.yyy.zzz.12
   hostname3  xxx.yyy.zzz.13
}
This configuration assumes you have a /24, and that you're using 
broadcast instead of multicast.  You could replace the (/24) broadcast 
address xxx.yyy.zzz.255 with the appropriate one for your network, or 
simply use a multicast addres instead if your network supports IP 
multicast.  Do NOT include the localhost address in your configuration. 
  Note that it may be necessary to specify at each host the hostname it 
is using (using spread -n hostname), depending on how your machines are 
configured.

I've descibed the benefits of using multiple daemons above.

 > I have looked at TIBCO's SmartPGM, which is not viable due to cost. 
JGroups advertises performance below that of Spread.
 >
 > Any help from anyone would be apprecieate,
 >
 > William Isley
 > IMS Consultants
 > 1250 N. Lakeview Ave, Suite A
 > Anaheim, CA  92807
 > Phone:  (714) 693-3505, x21
 > E-mail: wmisley at imsconsultants.com
 >
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-- 
Ryan W. Caudy
Center for Networking and Distributed Systems
Department of Computer Science
Johns Hopkins University