This tool can be used to gather Energy measurements on a SandyBridge
chip using RAPL.

Be sure to configure PAPI with --with-components="rapl" and have
read permissions on the /dev/cpu/*/msr files.

It works by using PAPI to poll the RAPL stats every 100ms.
It will dump each statistic to different files, which then
can be plotted.

The measurements (in nJ) are dumped every 100ms.  
You can adjust the frequency by changing the source code.

You can then take those files and put them into your favorite plotting 
program.  You might want to edit the source to remove the extra
commentary from the data, the plotting program I use ignores things
surrounded by (* brackets.