From 4a41c885ed0d55a2b754f40995f9753ddb37c065 Mon Sep 17 00:00:00 2001
From: paboyle <paboyle@ph.ed.ac.uk>
Date: Wed, 4 Nov 2015 03:24:19 -0800
Subject: [PATCH] Use Linux kernel interface to hardware performance counters.
 Dead useful.

---
 lib/PerfCount.h | 133 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 lib/PerfCount.h

diff --git a/lib/PerfCount.h b/lib/PerfCount.h
new file mode 100644
index 00000000..264d571e
--- /dev/null
+++ b/lib/PerfCount.h
@@ -0,0 +1,133 @@
+#ifndef GRID_PERFCOUNT_H
+#define GRID_PERFCOUNT_H
+
+#include <sys/time.h>
+#include <ctime>
+#include <chrono>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <syscall.h>
+#include <linux/perf_event.h>
+
+namespace Grid {
+
+
+static long perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
+			    int cpu, int group_fd, unsigned long flags)
+{
+  int ret;
+
+  ret = syscall(__NR_perf_event_open, hw_event, pid, cpu,
+		group_fd, flags);
+  return ret;
+}
+
+
+class PerformanceCounter {
+private:
+  typedef struct { 
+  public:
+    uint32_t type;
+    uint64_t config;
+    const char *name;
+  } PerformanceCounterConfig; 
+  
+  static const PerformanceCounterConfig PerformanceCounterConfigs [];
+
+public:
+
+  enum PerformanceCounterType {
+    CPUCYCLES=0,
+    INSTRUCTIONS,
+    //    STALL_CYCLES,
+    CACHE_REFERENCES,
+    CACHE_MISSES,
+    L1D_READ_MISS,
+    L1D_READ_ACCESS,
+    L1D_WRITE_MISS,
+    L1D_WRITE_ACCESS,
+    L1D_PREFETCH_MISS,
+    L1D_PREFETCH_ACCESS,
+    LL_READ_MISS,
+    //    LL_READ_ACCESS,
+    LL_WRITE_MISS,
+    LL_WRITE_ACCESS,
+    LL_PREFETCH_MISS,
+    LL_PREFETCH_ACCESS,
+    L1I_READ_MISS,
+    L1I_READ_ACCESS,
+    PERFORMANCE_COUNTER_NUM_TYPES
+  };
+
+public:
+    
+  int PCT;
+
+  struct perf_event_attr pe;
+  long long count;
+  int fd;
+  uint64_t elapsed;
+  uint64_t begin;
+
+  static int NumTypes(void){ 
+    return PERFORMANCE_COUNTER_NUM_TYPES;
+  }
+
+  PerformanceCounter(int _pct) {
+    assert(_pct>=0);
+    assert(_pct<PERFORMANCE_COUNTER_NUM_TYPES);
+    fd=-1;
+    count=0;
+    PCT =_pct;
+    Open();
+  }
+  void Open(void) 
+  {
+    memset(&pe, 0, sizeof(struct perf_event_attr));
+    pe.size = sizeof(struct perf_event_attr);
+
+    pe.disabled = 1;
+    pe.exclude_kernel = 1;
+    pe.exclude_hv = 1;
+    pe.inherit    = 1;
+
+    pe.type  = PerformanceCounterConfigs[PCT].type;
+    pe.config= PerformanceCounterConfigs[PCT].config;
+    const char * name = PerformanceCounterConfigs[PCT].name;
+    fd = perf_event_open(&pe, 0, -1, -1, 0); // pid 0, cpu -1 current process any cpu. group -1
+    if (fd == -1) {
+      fprintf(stderr, "Error opening leader %llx for event %s\n", pe.config,name);
+      perror("Error is");
+    }
+  }
+
+  void Start(void)
+  {
+    if ( fd!= -1) {
+      ioctl(fd, PERF_EVENT_IOC_RESET, 0);
+      ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);
+    }
+    begin  =__rdtsc();
+  }
+
+  void Stop(void) {
+    count=0;
+    if ( fd!= -1) {
+      ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
+      ::read(fd, &count, sizeof(long long));
+    }
+    elapsed = __rdtsc() - begin;
+  }
+  void Report(void) {
+    printf("%llu cycles %s = %20llu\n", elapsed , PerformanceCounterConfigs[PCT].name, count);
+  }
+
+  ~PerformanceCounter()
+  {
+    close(fd);
+  }
+
+};
+
+}
+#endif