[Spread-users] Slow receiver

Jonathan Stanton jonathan at cnds.jhu.edu
Wed Jan 28 21:50:24 EST 2004 

I'm not sure what you mean by "will it hurt?" You should usually have the 
IP addresses of the machines that are being used in your spread.conf and 
the broadcast address should be a valid broadcast address for your 
network. 

Since I'm not sure what kind of setup you are trying to configure spread 
for it's a little hard to provide any comments about whether it is the 
best configuration. So if you can let us know what you are trying to do, a 
number of people here could give you feedback on the configuration that 
will best achieve that goal. But tuning the config does depend on details 
like the speed of the network, how busy the network is, if you have 
multicast support, and on what hosts your applications will run.

The simple config of using your IP broadcast address, and listing all the 
relevant machines with their IP addresses in the segment will work well 
for most uses of spread -- so you might not need anything different in 
your spread.conf.

Cheers,

Jonathan

On Wed, Jan 28, 2004 at 05:10:14PM -0800, Anurag Gupta wrote:
> It turned out the problem was not having localhost within the segment. The
> problem was that spread daemon was not able to send messages to 127.0.0.255.
> Enabling logging showed this and this helped me fix it quickly - I just put
> in the IP instead of 127.0.0.255. Will it hurt?
> 
> thanks
> -anurag
> 
> -----Original Message-----
> From: Jonathan Stanton [mailto:jonathan at cnds.jhu.edu]
> Sent: Tuesday, January 27, 2004 7:42 AM
> To: Anurag Gupta
> Cc: spread-users
> Subject: Re: [Spread-users] Slow receiver
> 
> 
> My first comment is I don't know if the spread.conf file you gave is
> exactly what you are using -- but if it is (and hte xxx.xxx addresses are
> real IP addresses) then one problem is that you should not mix the
> internal localhost addresses and external ones. It doesn't make sense from
> Spread's point of view.
> 
> I think your config may sort of work if you only connect from a client
> running on the same machine as the daemon, but the 'client' and
> 'spread-daemon' machines will certainly not work.
> 
> If you are just running on one machine, then I'd try the config
> 
> Spread_Segment 127.0.0.255:4803 {
> 	localhost 127.0.0.1
> }
> 
> If you are connecting clients from other machines or using multiple
> daemons I'd do aconfig like:
> 
> Spread_Segment xxx.yyy.zzz.255:4803 {
> 	client   xxx.yyy.zzz.1
> 	spread-daemon xxx.yyy.zzz.2
> }
> 
> (Obviously with real addresses. The key change is you should not include
> localhost in the set of machines if you are not ONLY using localhost).
> 
> You are correct about what data_link is doing. It retries the sends on
> error to overcome transient errors. The question is why is the send
> failing in the first case. From the error I'm guessing it might be because
> of the config file having both localhost and remote addresses.
> 
> The best thing to do is try with one of the config files listed above and
> if that doesn't fix it, then turn on the DATALINK debug flag by adding
> 
> DebugFlags = { PRINT EXIT DATA_LINK }
> EventLogFile = bad_sendmsg.log
> 
> Then run spread and your test program. This will generate a log file
> "bad_sendmsg.log" that has every send call logged and should report more
> information that might show me what the error is.
> 
> Cheers,
> 
> Jonathan
> 
> On Mon, Jan 26, 2004 at 09:33:35PM -0800, Anurag Gupta wrote:
> > Thanks for your quick response.
> >
> > Latency of each message is ~200ms. ktracing the spread daemon (we are on
> > free bsd) led us to multiple sendmsg's failling for each one succeeding. I
> > think num_try is restricted to 10 in data_link.c thats why it stops after
> > 200ms. When I do a dump from ktrace, I see 10 of these for each successful
> > sendmsg:
> >
> > ==============
> >  61327 spread   0.000004 RET   select 0
> >  61327 spread   0.000003 CALL  sendmsg(0x5,0x80b1ae4,0)
> >  61327 spread   0.000005 RET   sendmsg -1 errno 49 Can't assign requested
> > address
> >  61327 spread   0.000004 CALL  select(0,0,0,0,0x806a824)
> > ===============
> >
> >
> > Only uncommented lines in spread.conf are:
> >
> > ==========
> > Spread_Segment  127.0.0.255:4803 {
> >   localhost   127.0.0.1
> >   client  xxx.xxx.xxx.xxx
> >   spread-daemon xxx.xxx.xxx.xxx
> > }
> > ==========
> >
> > thanks
> > -anurag
> >
> > -----Original Message-----
> > From: spread-users-admin at lists.spread.org
> > [mailto:spread-users-admin at lists.spread.org]On Behalf Of Jonathan
> > Stanton
> > Sent: Monday, January 26, 2004 8:54 PM
> > To: Anurag Gupta
> > Cc: spread-users
> > Subject: Re: [Spread-users] Slow receiver
> >
> >
> > Hi,
> >
> > I don't have quite enough information to know what is going on. Generally
> > the latency of a single message send in Spread should be quite low. On
> > modern machines, maybe in the neighborhood of a few hundred microseconds
> > of work plus scheduling delays (switching between client, daemon, back to
> > client if run on one machine) of anywhere from a few milliseconds to 30
> > ms.
> >
> > Can you provide us with your spread.conf configuration and some more
> > information about how much the receiver is lagging (what the delay is) and
> > the rough computer power? How are you timing the send time vs receive
> > time? Are they on different machines?
> >
> > One note, although it isn't necessarily affecting your results,
> > on most OS's sleeping for 1ms actually sleeps for 10+ms since 10 ms is the
> > minimum scheduling delay.
> >
> > Cheers,
> >
> > Jonathan
> >
> > On Mon, Jan 26, 2004 at 08:43:27PM -0800, Anurag Gupta wrote:
> > > Hi,
> > >
> > > I am seeing some unusual delays in getting spread to transfer messages.
> I
> > > have a simple flooder sleeping 1 millis after publishing each message
> > > (message size 100 bytes), and a receiver receiving those messages (no
> > > processing done). Receiver is lagging behind in receiving the messages
> > quite
> > > a bit.
> > >
> > > How do I see where the delay is? Is this expected? Or a result of some
> > > misconfiguration?
> > >
> > > regards
> > > -anurag
> > >
> > >
> > > _______________________________________________
> > > Spread-users mailing list
> > > Spread-users at lists.spread.org
> > > http://lists.spread.org/mailman/listinfo/spread-users
> >
> > --
> > -------------------------------------------------------
> > Jonathan R. Stanton         jonathan at cs.jhu.edu
> > Dept. of Computer Science
> > Johns Hopkins University
> > -------------------------------------------------------
> >
> > _______________________________________________
> > Spread-users mailing list
> > Spread-users at lists.spread.org
> > http://lists.spread.org/mailman/listinfo/spread-users
> >
> >
> 
> --
> -------------------------------------------------------
> Jonathan R. Stanton         jonathan at cs.jhu.edu
> Dept. of Computer Science
> Johns Hopkins University
> -------------------------------------------------------
> 
> 

-- 
-------------------------------------------------------
Jonathan R. Stanton         jonathan at cs.jhu.edu
Dept. of Computer Science   
Johns Hopkins University    
-------------------------------------------------------

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