Event based sampling uses counters on the Intel processors to detect what your software is doing. This is helpful for tuning and improving software performance. Typical hotspot analysis shows you where your software spends most of the execution time, but event based sampling allows you to see not just what sections of your application take the most time but why and what it is doing.
The events are different for each platform so you need to know what platform you are executing your software on. We just recently updated our guide to event based tuning on the popular Intel(R) Core(TM) i7 processor based platforms. The guide is updated to include suggestions for both single socket and dual socket systems. Check out: http://software.intel.com/en-us/articles/using-intel-vtune-performance-analyzer-to-optimize-software-for-the-intelr-coretm-i7-processor-family/
Many of you following our platforms know that on our new platforms the memory bandwidth measurements can no longer be done on the core processor. For those who want to measure bandwidth on the Intel(r) Core(TM) i7 processor based platforms we have enabled a method using uncore events. Check out this link: http://software.intel.com/en-us/articles/how-do-i-measure-memory-bandwidth-on-an-intel-core-i7-or-xeon-5500-series-platform-using-intel-vtune-performance-analyzer/ You must have a VTune Performance Analyzer License and you will also need to download the Performance Tuning Utility from whatif.intel.com.