Hi Brian, thx for this, way more intuitive than kcachegrind, gprof and friends. Attached is one log file for the example I described below. All 3 "rostopic" calls are denoted as the "python" process in the log file I guess. It seems that the most of the system time is indeed spent for the memcpy and memset directives - time to try out nodelets apparently:-). I do not really understand what does the "in kernel" stand for? cheers, D. On Mon, Apr 19, 2010 at 4:47 PM, Brian Gerkey wrote: > hi Dejan, > > It would be interesting to see some data from a profiler to understand > where the publishing node is spending its time.  We usually use > sysprof: http://pr.willowgarage.com/wiki/sysprof . > >        brian. > > On Sun, Apr 18, 2010 at 1:37 PM, Dejan Pangercic > wrote: >> Hi there, >> >> I ran the program with the valgrind and found nothing fishy. Moreover >> it turned out that the decay in publishing rate only happens when >> there is a subscriber such as e.g. image_view subscribed to the topic. >> What I then tried next was to subscribe to the output topic with 3 >> "rostopic hz /image_topic_2" commands only - see also an attached >> rxgraph plot. >> This resulted in every subscription having less and less publishing >> rate (~ 30, 25 and 26 Hz respectively). Once again I ran this on one >> machine and over the loopback. The program publishing images is now >> also in tum-ros-pkg repo: >> http://tum-ros-pkg.svn.sourceforge.net/viewvc/tum-ros-pkg/perception/image_algos/utils/openCV_to_ros.cpp?revision=432&view=markup >> if someone wants to give it a try. >> >> Could the decay in publishing rate be attributed to the way ROS's >> subscribe mechanism handles the copying of data? >> >> cheers, D. >> >> >> On Fri, Apr 16, 2010 at 9:47 PM, Josh Faust wrote: >>> Whoops, should've looked at the attached source.  In general a profiler is >>> going to tell you what's taking time far better than we will. >>> >>> Josh >>> >>> On Fri, Apr 16, 2010 at 12:33 PM, Dejan Pangercic >>> wrote: >>>> >>>> Hi Josh, >>>> >>>> I did not do profiling yet. However, since I read the image only once >>>> when I start the program and then publish it from the memory, it can >>>> not be harddrive. >>>> D. >>>> >>>> On Fri, Apr 16, 2010 at 9:00 PM, Josh Faust >>>> wrote: >>>> > Have you tried profiling it to see where the time is being spent, and >>>> > where >>>> > the bottleneck is?  1.8MB * 30 = 54MB/sec, which could actually be >>>> > harddrive-limited depending on the drive you're reading from. >>>> > >>>> > Josh >>>> > >>>> > On Fri, Apr 16, 2010 at 11:26 AM, Dejan Pangercic >>>> > wrote: >>>> >> >>>> >> Hi there, >>>> >> >>>> >> I using an attached program to read an image from a disk and to then >>>> >> continously publish it on an image topic at 30 fps. On _one_ machine >>>> >> over loopback. When I tried it with a 1608x1236+0+0 color image >>>> >> (1.8MB) and then used rostopic hz to display the publishing rate of >>>> >> topic, >>>> >> the most that I got was around 12, 13 Hz. >>>> >> Any idea what would cause such a low performance? At what rates and >>>> >> sizes do you folks usually send images around? >>>> >> >>>> >> thx and cheers, D. >>>> >> >>>> >> -- >>>> >> MSc. Dejan Pangercic >>>> >> PhD Student/Researcher >>>> >> Computer Science IX >>>> >> Technische Universität München >>>> >> Telephone: +49 (89) 289-17780 >>>> >> E-Mail: dejan.pangercic@in.tum.de >>>> >> WWW: http://ias.cs.tum.edu/people/pangercic >>>> >> >>>> >> _______________________________________________ >>>> >> ros-users mailing list >>>> >> ros-users@code.ros.org >>>> >> https://code.ros.org/mailman/listinfo/ros-users >>>> >> >>>> > >>>> > >>>> > _______________________________________________ >>>> > ros-users mailing list >>>> > ros-users@code.ros.org >>>> > https://code.ros.org/mailman/listinfo/ros-users >>>> > >>>> > >>>> >>>> >>>> >>>> -- >>>> MSc. Dejan Pangercic >>>> PhD Student/Researcher >>>> Computer Science IX >>>> Technische Universität München >>>> Telephone: +49 (89) 289-17780 >>>> E-Mail: dejan.pangercic@in.tum.de >>>> WWW: http://ias.cs.tum.edu/people/pangercic >>>> _______________________________________________ >>>> ros-users mailing list >>>> ros-users@code.ros.org >>>> https://code.ros.org/mailman/listinfo/ros-users >>> >>> >>> _______________________________________________ >>> ros-users mailing list >>> ros-users@code.ros.org >>> https://code.ros.org/mailman/listinfo/ros-users >>> >>> >> >> >> >> -- >> MSc. Dejan Pangercic >> PhD Student/Researcher >> Computer Science IX >> Technische Universität München >> Telephone: +49 (89) 289-17780 >> E-Mail: dejan.pangercic@in.tum.de >> WWW: http://ias.cs.tum.edu/people/pangercic >> >> >> >> -- >> MSc. Dejan Pangercic >> PhD Student/Researcher >> Computer Science IX >> Technische Universität München >> Telephone: +49 (89) 289-17780 >> E-Mail: dejan.pangercic@in.tum.de >> WWW: http://ias.cs.tum.edu/people/pangercic >> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users >> >> > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users > -- MSc. Dejan Pangercic PhD Student/Researcher Computer Science IX Technische Universität München Telephone: +49 (89) 289-17780 E-Mail: dejan.pangercic@in.tum.de WWW: http://ias.cs.tum.edu/people/pangercic