# Perf benchmark

### Overview

- Using <i>perf_event_open</i> to get hardware and software counters.
- Only useful when you want to measure something inside the code really quick.  
  Otherwise, use <i>perf</i> itself.
- Linux only.
- All predefined hardware and software counters are generated in the header  
  file, you can uncomment counters as you wish. 
- If some counters or combination of counters doesnt work or doesn't work as  
  expected, please check out performance counter register allocation  
  documentation for your CPU. CPUs have limited registers for performance  
  counters and some counters can use specific registers only. 
- Just copy <b>sc_perf.h</b> and <b>sc_perf.c</b> to your project.

#### Usage

```c

#include "sc_perf.h"  

int main(int argc, char *argv[])
{
    sc_perf_start();

    long_running_operation();

    sc_perf_end();
  
    return 0;
}

```
##### Output will be like
```
| Event                     | Value              | Measurement time  
---------------------------------------------------------------
| time (seconds)            | 0.66               | (100,00%)  
| cpu-clock                 | 654075766.00       | (100.00%)  
| task-clock                | 654077198.00       | (100.00%)  
| page-faults               | 3.00               | (100.00%)  
| context-switches          | 46.00              | (100.00%)  
| cpu-migrations            | 0.00               | (100.00%)  
| page-fault-minor          | 3.00               | (100.00%)  
| cpu-cycles                | 2656529748.00      | (100.00%)  
| instructions              | 7589235720.00      | (100.00%)  
| cache-misses              | 28715.00           | (100.00%)  
| L1D-read-miss             | 34124.00           | (100.00%)  
| L1I-read-miss             | 121958.00          | (100.00%) 
```

##### Pause example
```c

#include "sc_perf.h"

int main(int argc, char *argv[])
{
    sc_perf_start();

    long_running_operation();

    //Will stop counters.
    sc_perf_pause();
    operation_you_dont_want_to_measure();

    //Start counters again.
    sc_perf_start();
    another_long_running_operation();

    sc_perf_end();
    
    sc_perf_start();
    some_other_long_running_operation();
    sc_perf_end();
  
    return 0;
}

```