Cedric Pradalier wrote:
> Hi,
>
> this discussion raised my curiosity, so I created a small test program
> to evaluate the advantage of using shared memory. The program is quite
> simple: on one end a publisher is creating an image of some size, and
> publishing it with a timestamp given by ros::Time::now(), on the other
> end, a receiver is receiving the image, and recording the difference
> between ros::Time::now() and the image timestamp.
>
> I made this test for 1000 images, from 640x480x1, 640x480x3,
> 1500x1000x3, 3000x2000x3. The results are summarised in the attached pdf.
>
> I also attach the test file so that someone can point out if something
> is wrong in my test.
>
> The bottom line is: for big object, shared memory transfer reduces
> significantly the delivery delay.
>
> I hope that helps.
I also add the variation of the reception interframe time in the plot,
as delivery delay is not the only parameter affected by the type of
transport.
Best
--
Dr. Cedric Pradalier
http://www.asl.ethz.ch/people/cedricp
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