[Spread-users] Optimal message size.

Yair Amir yairamir at cnds.jhu.edu
Thu Aug 9 19:53:37 EDT 2001

Hi Theo,

Perhaps I did not understand your question. But if your messages are one order of magnitude larger than the Ethernet MTU (i.e. they are 5-10 KBytes) the best is to not split them and give them to Spread using one SP_multicast.

Actually, for any size up to the max spread message, the best is not to split. The reason is that if you do not split, Spread optimizes its packets. If you do split unnecesarily, be aware that Spread will add a message header (pretty big - 80 - 100 bytes or so depending on the version and wide area support) to every "split" it gets.

There is no relation between message size and memory footprint if the messages are large (5-10Kbytes). The relation is between (more or less) the total number of bytes that are pending (a different way to say - total number of spread packets).


	:) Yair.

"Theo E. Schlossnagle" wrote:
> I am writing an application that multicasts data messages that are of
> substantial size -- meaning there are at least one order of magnitude larger
> that the Ethernet MTU I am riding on.
> The nature of my application will allow me to split them up into chucks of any
> size.  And I would much rather the memory footprint of my app to increase as
> opposed to Spread's.
> So, since I can choose exactly how my message gets chopped up before I send it
> to Spread, what is the optimal size for the data buffer passed to
> "SP_multicast()" assuming 1 group and assuming n groups?
> Thanks!
> --
> Theo Schlossnagle
> 1024D/82844984/95FD 30F1 489E 4613 F22E  491A 7E88 364C 8284 4984
> 2047R/33131B65/71 F7 95 64 49 76 5D BA  3D 90 B9 9F BE 27 24 E7
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