[PD] iemnet/tcpserver too sloooooow

rolfm at dds.nl rolfm at dds.nl
Tue Jan 17 17:28:49 CET 2017

thanks Roman for your explanation.

-question: is [iemnet/tcpserver] packaged in Pd-extended also threaded?
because that one (on the mac) gives a overall time comparable with 

measuring  (with [timer]) the, what you call, roundtrip time for each 
'phrase' gives these results :

w10->mac:  0-100 msec, 80% between 4-10 msec. (25 sec for whole 
w10->pi : 30-53 msec, 95% between 36-43 msec. (150 sec)
mac->w10: 53-300 msec,90% between 55-60 msec. (200 sec)

without sending back the 'ok' byte the transfer of all data takes less 
then 1 msec.

i don't know yet what 'being threaded' exactly means,
but if you're right, these vast numbers tell me that communication with 
a threaded process is very costly.

about the ""chattiness" of my application layer protocol":
my goal is an embedded system, raspberry-pi connected with a serial 
cable to an Arduino,
where the Pi takes care of the wifi communication with a front-end 

the 'ok' byte is necessary to know for sure that the Arduino did indeed 
receive and
process each 'phrase' of data.


> Roman wrote:
> On Don, 2017-01-12 at 14:46 +0100, rolfm at dds.nl wrote:
>> i'm sending data using tcpserver & tcpclient over wifi with a router
>> in 
>> a local network.
>> the source patch sends 6 bytes and then waits until
>> a single byte comes back that signals the next 6 bytes can be sent.
>> in total 3538 data recs of 6 bytes are sent.
>> what could be the reason for this behaviour?
> The "chattiness" of your application layer protocol. You went for the
> least optimal way to achieve high throughput. As for why there is a
> difference between Pd's [netsend]/[netreceive] and iemnet's
> [tcpclient]/[tcpserver] I can only guess. I believe Pd's implementation
> is not threaded and is executed directly in the DSP thread, while
> iemnet classes are threaded. While using threads is often the better
> solution, because it avoids blocking Pd when the network buffer is
> full, I assume it takes a little wee bit more time for the message to
> be passed from the Pd's main thread to the networking thread and thus
> increases the overall round trip time slightly. Since your protocol
> requires a full round trip for every 6 bytes, the small increase in
> round trip is amplified by the high number of round trips required. 
> I could imagine that the situation might be improved by lowering the
> latency in Pd's audio settings, but that's not a very substantiated
> guess.
> Imagine you use the protocol between two computers that are more apart
> from each other (i.e. not in the same LAN). An increase of round trip
> time from 1ms to 10ms would reduce your throughput by a factor of 10.
>> a bug?
> I don't think so. My advice is to rethink your application layer
> protocol. Try to reduce the "multi-ping-pong" to just one ping
> (containing all requests in one message) from the requesting party,
> answered by a single pong message from the providing party.
> Let me tell from my experience, the iemnet classes are performing _well
> enough_ (if not excellently). It's easy to create a patch that
> saturates a 100Mbit/s link without consuming much CPU. 
> Roman

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