[ros-users] ROS communication performance .

[Alex Barvo]

Ken,

The paper you pointed to was using Box Turtle and found that performance of
ROS wss pretty good compared to (what appears to be very optimised) LCM.
Do you think C-turtle got any improvements in this area?

>From paper:

>The ROS TCP transport achieves high throughput when the maximum queue
length (q) is set to infinity, but at the

>expense of message latency. Various settings of q provide an adjustable
tradeoff between throughput and latency.

On Thu, Sep 9, 2010 at 12:06 PM, Ken Conley <kwc at willowgarage.com> wrote:

> Hi Konrad,
>
> If you read this paper from the authors of LCM, you will find that the
> performance of ROS, LCM, and IPC are generally comparable (note: the
> article tests LCM's UDP implementation against ROS' TCP
> implementation):
>
> http://lcm.googlecode.com/files/2010-huang-olson-moore-lcm-iros.pdf
>
> Comparing any middleware to "raw TCP" is generally difficult to come
> to conclusions, especially without including exact information on how
> your test was conducted. With any middleware, there is the overhead of
> (un)marshaling the data into individual messages.  The size and
> composition of these messages is a significant factor in any
> performance numbers that result.
>
> - Ken
>
> On Thu, Sep 9, 2010 at 11:48 AM, Konrad Banachowicz <konradb3 at gmail.com>
> wrote:
> > Dear all,
> > I recently done some testing on ROS communication performence.
> > There are the reesults :
> >                           throughput [MB/s]     time [s]           data
> [MB]
> > ROS                 7.25906                      4.827058      35.0399
> > raw TCP          56.8430                      8.387205      476.75466
> > POSIX MQ      124.36626                  3.834136      476.837158
> >
> > That shows grate overhead of ROS communication.
> > I looked on code, I found that the communication code is very complicated
> > and contains many locks and queues. It's also integrate interprocess and
> > intraprocess communication. This with all callback stuff make whole
> > communication overcomplicated.
> >
> > I think this show serious problem with design of whole network stack in
> ROS.
> >
> > I will do some more testing.
> >
> > Pozdrawiam
> > Konrad Banachowicz
> >
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> >
> >
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