[zeromq-dev] Bad ZMQ latency on first 500 messages per connection

Ben Kloosterman bklooste at gmail.com
Tue Sep 29 08:49:28 CEST 2015


"As can be seen, sender and receiver throughput's differ at the beginning
of the test. This seems to suggest that there is some kind of buffering
involved on the lower layers of the stack"

Nagle is turned off  but it looks like it keeps increasing some sort of
buffer in the tcp stack.. could also be OS / memory ( page allocation)  /
Scheduling priority.

Note in those 500 messages the sender was sending a lot more messages ,
than the receiver was receiving so a buffer would be growing somewhere.

Ben

On Tue, Sep 29, 2015 at 4:35 PM, <Christian.Kohrt at rohde-schwarz.com> wrote:

> Hi all,
>
> when sending many messages at once there is a known latency issue: The
> first 500 messages are sent with a high latency shown in the graph in the
> whitepaper *http://zeromq.org/whitepapers:measuring-performance*
> <http://zeromq.org/whitepapers:measuring-performance> before it gets to
> very high speed messaging.
>
> The author summarizes:
> * For latency: ... the latency for first 500 messages is quite poor (up to
> 1,500 microseconds), however, afterwards it stabilises at approximately 150
> microseconds, with occasional peaks up to 400 microseconds.
> * For throughput: This seems to suggest that there is some kind of
> buffering involved on the lower layers of the stack.
>
> In our scenario, we use a Dealer/Router connection, which is in fact like
> REQ/REP.
>
> Question:
> Why have the first 500 messages this latency issue? What is the reason for
> this and how could we solve this issue, because we require a high
> performance application even for the first messages.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.zeromq.org/pipermail/zeromq-dev/attachments/20150929/bcfa22d0/attachment.htm>


More information about the zeromq-dev mailing list