Add missing file

Author: thomasmueller

benchmarks/linux-perf-events.h

@@ -0,0 +1,88 @@
+// https://github.com/WojciechMula/toys/blob/master/000helpers/linux-perf-events.h
+#pragma once
+#ifdef __linux__
+
+#include <asm/unistd.h>       // for __NR_perf_event_open
+#include <linux/perf_event.h> // for perf event constants
+#include <sys/ioctl.h>        // for ioctl
+#include <unistd.h>           // for syscall
+
+#include <cerrno>  // for errno
+#include <cstring> // for memset
+#include <stdexcept>
+
+#include <vector>
+
+template <int TYPE = PERF_TYPE_HARDWARE> class LinuxEvents {
+  int fd;
+  perf_event_attr attribs;
+  int num_events;
+  std::vector<uint64_t> temp_result_vec;
+  std::vector<uint64_t> ids;
+
+public:
+  LinuxEvents(std::vector<int> config_vec) : fd(0) {
+    memset(&attribs, 0, sizeof(attribs));
+    attribs.type = TYPE;
+    attribs.size = sizeof(attribs);
+    attribs.disabled = 1;
+    attribs.exclude_kernel = 1;
+    attribs.exclude_hv = 1;
+
+    attribs.sample_period = 0;
+    attribs.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
+    const int pid = 0;  // the current process
+    const int cpu = -1; // all CPUs
+    const unsigned long flags = 0;
+
+    int group = -1; // no group
+    num_events = config_vec.size();
+    uint32_t i = 0;
+    for (auto config : config_vec) {
+      attribs.config = config;
+      fd = syscall(__NR_perf_event_open, &attribs, pid, cpu, group, flags);
+      if (fd == -1) {
+        report_error("perf_event_open");
+      }
+      ioctl(fd, PERF_EVENT_IOC_ID, &ids[i++]);
+      if (group == -1) {
+        group = fd;
+      }
+    }
+
+    temp_result_vec.resize(num_events * 2 + 1);
+  }
+
+  ~LinuxEvents() { close(fd); }
+
+  inline void start() {
+    if (ioctl(fd, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP) == -1) {
+      report_error("ioctl(PERF_EVENT_IOC_RESET)");
+    }
+
+    if (ioctl(fd, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP) == -1) {
+      report_error("ioctl(PERF_EVENT_IOC_ENABLE)");
+    }
+  }
+
+  inline void end(std::vector<unsigned long long> &results) {
+    if (ioctl(fd, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP) == -1) {
+      report_error("ioctl(PERF_EVENT_IOC_DISABLE)");
+    }
+
+    if (read(fd, &temp_result_vec[0], temp_result_vec.size() * 8) == -1) {
+      report_error("read");
+    }
+    // our actual results are in slots 1,3,5, ... of this structure
+    // we really should be checking our ids obtained earlier to be safe
+    for (uint32_t i = 1; i < temp_result_vec.size(); i += 2) {
+      results[i / 2] = temp_result_vec[i];
+    }
+  }
+
+private:
+  void report_error(const std::string &context) {
+    throw std::runtime_error(context + ": " + std::string(strerror(errno)));
+  }
+};
+#endif