1. What Are Performance Counters?
Performance counters are a special set of registers, most commonly found on a processor chip, which count a number of different events that occur inside the computer when an application is being executed.

2. Why Are They Important?
Performance analysis helps programmers find bottlenecks
in their programs, allowing them to build more time-efficient applications.

3. Tools
PAPI: Provides a graphical user interface to access the performance counters. It allows the user to dynamically select and display performance counter data, i.e., count specific events.
Micro-benchmarks: Small programs designed to use specific computer resources which, in turn, generate events recorded by performance counters. Due to their simplicity and our knowledge of the target processor architecture we can predict event counts, which are used to test performance counter accuracy.

4. Tools
Simulators: Processor simulators used to refine our micro-benchmarks and the algorithms used to predict event counts for these micro-benchmarks.

5. Types of Micro-benchmarks
Kind
Reason
linear
Instruction cache miss events
loop
Store, load, and branch-prediction events
array
Data cache miss events

6. Designing Micro-benchmarks
A micro-benchmark must be simple enough to allow for the algorithmic calculation of event counts, i.e., calculation without using performance counter data. This prediction is an expected result for the event counts recorded by performance counters.