Nagle’s algo is already disabled in the codebase (you can confirm that with a quick grep). I think what Bruno is referring to is that zeromq batches small messages into larger ones before sending. This improves throughput at the cost of latency as expected.
Check out the “performance” section of the FAQ for an explanation: http://zeromq.org/area:faq On Jan 16, 2014, at 7:04 AM, Lindley French <[email protected]> wrote: > Ah, that would explain it, yes. It would be great to have a way of disabling > Nagle's algorithm (TCP_NODELAY sockopt). > > > On Thu, Jan 16, 2014 at 4:24 AM, Bruno D. Rodrigues > <[email protected]> wrote: > Without looking at the code I assume ØMQ is not trying to send each > individual message as a TCP PDU but instead, as the name implies, queues > messages so it can batch them together and get the performance. > > This then means the wire will be filled up when some internal buffer fills, > or after a timeout, which looks like 100ms. > > On the other hand I can’t see any setsockopt to configure this possible > timeout value. > > Any feedback from someone else before I have time to look at the code? > > On Jan 15, 2014, at 16:20, Lindley French <[email protected]> wrote: > > > I have a test case in which I'm communicating between two threads using zmq > > sockets. The fact that the sockets are in the same process is an artifact > > of the test, not the real use-case, so I have a TCP connection between them. > > > > What I'm observing is that a lot of the time, it takes ~100 milliseconds > > between delivery of a message to the sending socket and arrival of that > > message on the receiving socket. Other times (less frequently) it is a > > matter of microseconds. I imagine this must be due to some kernel or thread > > scheduling weirdness, but I can't rule out that it might be due to > > something in 0MQ. > > > > If I follow the TCP socket write with one or more UDP writes using > > Boost.Asio, the 100 millisecond delay invariably occurs for the ZMQ TCP > > message but the UDP messages arrive almost instantly (before the TCP > > message). > > > > My design requires that the TCP message arrive before *most* of the UDP > > messages. It's fine if some come through first----UDP is faster after all, > > that's why I'm using it----but this big of a delay is more than I counted > > on, and it's concerning. I don't know if it would apply across a real > > network or if it's an artifact of testing in a single process. > > > > Any insights? > > _______________________________________________ > > zeromq-dev mailing list > > [email protected] > > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > > > _______________________________________________ > zeromq-dev mailing list > [email protected] > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > > > _______________________________________________ > zeromq-dev mailing list > [email protected] > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
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