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Birds Eye View/Performance/Profiling: Difference between revisions
Birds Eye View/Performance/Profiling (view source)
Revision as of 17:07, 27 February 2020
, 27 February 2020→Application Profiling
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= Application Profiling = | = Application Profiling = | ||
The library supports a application profiling as a developer oriented feature using [https://github.com/gperftools/gperftools/wiki gperftools]. | |||
= GPerfTools Installation = | |||
Install the library packages from github repository | |||
<source lang="bash"> | |||
git clone https://github.com/gperftools/gperftools | |||
cd gperftools | |||
./autogen.sh | |||
./configure | |||
make | |||
sudo make install | |||
</source> | |||
On debian-based systems the complementary tools are packaged under the google-perftools package. For graphical output you also need graphviz installed: | |||
<source lang="bash"> | |||
sudo apt-get install google-perftools graphviz | |||
</source> | |||
Note that all the tools have the “google-” prefix under debian - the prefix may be missing on other systems (and is also missing in the official documentation). | |||
= BEV examples profiling = | |||
To enable profiling execute meson and compile the library with the following option: | |||
<source lang="bash"> | |||
meson -Dprofiling=enabled .. | |||
ninja | |||
</source> | |||
== A) Profile the whole process runtime == | |||
'''1.''' To start profiling run: | |||
'''LD_PRELOAD:''' Path to the libprofiler.so usually located at /usr/local/lib/ | |||
'''CPUPROFILE:''' Name of the output log file | |||
<source lang="bash"> | |||
LD_PRELOAD=/usr/local/lib/libprofiler.so CPUPROFILE=test.prof ./path/to/bin | |||
</source> | |||
'''2.''' Keep the application open or running until it finishes, in this mode if the execution is canceled | |||
for example with Ctrl+C the output file will not be generated. | |||
'''3.1''' Once the application ended the ''test.prof'' file contains the CPU profile information. To get a graphical output run: | |||
<source lang="bash"> | |||
pprof -gv ./path/to/bin test.prof | |||
</source> | |||
'''3.2''' Also as an alternative viewer you can display it to a web browser by running: | |||
<source lang="bash"> | |||
pprof --web ./path/to/bin test.prof | |||
</source> | |||
'''4.''' To generate a PDF report with the previous graphic output run: | |||
<source lang="bash"> | |||
pprof --pdf ./path/to/bin test.prof > output.pdf | |||
</source> | |||
Example graphical output: | |||
[[File:Bev pprof.png|700px|frameless|center]] | |||
== B) Profile part of process runtime == | |||
In addition to defining the environment variable '''CPUPROFILE''' you can also define '''CPUPROFILESIGNAL'''. This allows profiling to be controlled via the signal number that you specify. The signal number must be unused by the program under normal operation. Internally it acts as a switch, triggered by the signal, which is off by default. | |||
'''1.''' To start profiling run: | |||
<source lang="bash"> | |||
LD_PRELOAD=/usr/local/lib/libprofiler.so CPUPROFILE=test.prof CPUPROFILESIGNAL=12 ./path/to/bin | |||
</source> | |||
'''2.''' Leave the program running until you want to start the profiling process. Then send the signal: | |||
'''2.1''' You can use '''htop''' program to send the signal to the desired process: | |||
[[File:Bev htop.png|600px|frameless|center]] | |||
'''2.1''' Also you can use '''killall''' command to send the ''-12'' signal | |||
<source lang="bash"> | |||
killall -12 /path/to/bin | |||
</source> | |||
'''3.''' Leave the program until the point you want to profile it, then run again: | |||
<source lang="bash"> | |||
killall -12 /path/to/bin | |||
</source> | |||
You will notice the following output when the output file was correctly generated: | |||
<source lang="bash"> | |||
Using signal 12 as cpu profiling switch | |||
PROFILE: interrupts/evictions/bytes = 4773/1826/231936 | |||
</source> | |||
'''4.''' Once the application ended the ''test.prof.0'' file contains the CPU profile information. To get a graphical output run: | |||
<source lang="bash"> | |||
pprof -gv ./path/to/bin test.prof | |||
</source> | |||
== C) Profile specific section of source code == | |||
'''1.''' Add the header file in your code: | |||
<source lang="C"> | |||
#include <gperftools/profiler.h> | |||
</source> | |||
'''2.''' Add the following functions calls around the code you want to profile: | |||
<source lang="C"> | |||
ProfilerStart("output_inside.prof"); //Start profiling section and save to file | |||
/* | |||
* Code to be analyzed | |||
*/ | |||
ProfilerStop(); //End profiling section | |||
</source> | |||
'''3.''' Run the test application, where you will an output similar to the following: | |||
<source lang="bash"> | |||
fsolano@ridgerun-laptop:build$ ./test | |||
PROFILE: interrupts/evictions/bytes = 9/0/280 | |||
PROFILE: interrupts/evictions/bytes = 7/0/584 | |||
PROFILE: interrupts/evictions/bytes = 12/0/872 | |||
PROFILE: interrupts/evictions/bytes = 9/0/712 | |||
PROFILE: interrupts/evictions/bytes = 9/0/904 | |||
PROFILE: interrupts/evictions/bytes = 7/0/464 | |||
PROFILE: interrupts/evictions/bytes = 8/0/680 | |||
</source> | |||
'''4.''' With this method you can wait until the application execution ends, or end it with Ctrl+C. | |||
'''5.''' Once the application ended the ''output_inside.prof'' file contains the CPU profile information. To get a graphical output run: | |||
<source lang="bash"> | |||
pprof -gv ./test output_inside.prof | |||
</source> | |||