Initial commit
Benchmark library builds and runs but only single-threaded. Multithreaded
support needs a bit more love.
Currently requires some C++11 support (g++ 4.6.3 seems to work).
diff --git a/src/sysinfo.cc b/src/sysinfo.cc
new file mode 100644
index 0000000..644b66f
--- /dev/null
+++ b/src/sysinfo.cc
@@ -0,0 +1,337 @@
+#include "sysinfo.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#include <iostream>
+#include <limits>
+
+#include "cycleclock.h"
+#include "macros.h"
+#include "mutex_lock.h"
+#include "sleep.h"
+
+namespace {
+pthread_once_t cpuinfo_init = PTHREAD_ONCE_INIT;
+double cpuinfo_cycles_per_second = 1.0;
+int cpuinfo_num_cpus = 1; // Conservative guess
+static pthread_mutex_t cputimens_mutex;
+
+// Helper function estimates cycles/sec by observing cycles elapsed during
+// sleep(). Using small sleep time decreases accuracy significantly.
+int64_t EstimateCyclesPerSecond(const int estimate_time_ms) {
+ CHECK(estimate_time_ms > 0);
+ double multiplier = 1000.0 / (double)estimate_time_ms; // scale by this much
+
+ const int64_t start_ticks = CycleClock::Now();
+ SleepForMilliseconds(estimate_time_ms);
+ const int64_t guess = int64_t(multiplier * (CycleClock::Now() - start_ticks));
+ return guess;
+}
+
+// Helper function for reading an int from a file. Returns true if successful
+// and the memory location pointed to by value is set to the value read.
+bool ReadIntFromFile(const char *file, int *value) {
+ bool ret = false;
+ int fd = open(file, O_RDONLY);
+ if (fd != -1) {
+ char line[1024];
+ char* err;
+ memset(line, '\0', sizeof(line));
+ CHECK(read(fd, line, sizeof(line) - 1));
+ const int temp_value = strtol(line, &err, 10);
+ if (line[0] != '\0' && (*err == '\n' || *err == '\0')) {
+ *value = temp_value;
+ ret = true;
+ }
+ close(fd);
+ }
+ return ret;
+}
+
+void InitializeSystemInfo() {
+ bool saw_mhz = false;
+
+ // TODO: destroy this
+ pthread_mutex_init(&cputimens_mutex, NULL);
+
+#if defined OS_LINUX || defined OS_CYGWIN
+ char line[1024];
+ char* err;
+ int freq;
+
+ // If the kernel is exporting the tsc frequency use that. There are issues
+ // where cpuinfo_max_freq cannot be relied on because the BIOS may be
+ // exporintg an invalid p-state (on x86) or p-states may be used to put the
+ // processor in a new mode (turbo mode). Essentially, those frequencies
+ // cannot always be relied upon. The same reasons apply to /proc/cpuinfo as
+ // well.
+ if (!saw_mhz &&
+ ReadIntFromFile("/sys/devices/system/cpu/cpu0/tsc_freq_khz", &freq)) {
+ // The value is in kHz (as the file name suggests). For example, on a
+ // 2GHz warpstation, the file contains the value "2000000".
+ cpuinfo_cycles_per_second = freq * 1000.0;
+ saw_mhz = true;
+ }
+
+ // If CPU scaling is in effect, we want to use the *maximum* frequency,
+ // not whatever CPU speed some random processor happens to be using now.
+ if (!saw_mhz &&
+ ReadIntFromFile("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq",
+ &freq)) {
+ // The value is in kHz. For example, on a 2GHz warpstation, the file
+ // contains the value "2000000".
+ cpuinfo_cycles_per_second = freq * 1000.0;
+ saw_mhz = true;
+ }
+
+ // Read /proc/cpuinfo for other values, and if there is no cpuinfo_max_freq.
+ const char* pname = "/proc/cpuinfo";
+ int fd = open(pname, O_RDONLY);
+ if (fd == -1) {
+ perror(pname);
+ if (!saw_mhz) {
+ cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
+ }
+ return; // TODO: use generic tester instead?
+ }
+
+ double bogo_clock = 1.0;
+ bool saw_bogo = false;
+ int max_cpu_id = 0;
+ int num_cpus = 0;
+ line[0] = line[1] = '\0';
+ int chars_read = 0;
+ do { // we'll exit when the last read didn't read anything
+ // Move the next line to the beginning of the buffer
+ const int oldlinelen = strlen(line);
+ if (sizeof(line) == oldlinelen + 1) // oldlinelen took up entire line
+ line[0] = '\0';
+ else // still other lines left to save
+ memmove(line, line + oldlinelen+1, sizeof(line) - (oldlinelen+1));
+ // Terminate the new line, reading more if we can't find the newline
+ char* newline = strchr(line, '\n');
+ if (newline == NULL) {
+ const int linelen = strlen(line);
+ const int bytes_to_read = sizeof(line)-1 - linelen;
+ CHECK(bytes_to_read > 0); // because the memmove recovered >=1 bytes
+ chars_read = read(fd, line + linelen, bytes_to_read);
+ line[linelen + chars_read] = '\0';
+ newline = strchr(line, '\n');
+ }
+ if (newline != NULL)
+ *newline = '\0';
+
+ // When parsing the "cpu MHz" and "bogomips" (fallback) entries, we only
+ // accept postive values. Some environments (virtual machines) report zero,
+ // which would cause infinite looping in WallTime_Init.
+ if (!saw_mhz && strncasecmp(line, "cpu MHz", sizeof("cpu MHz")-1) == 0) {
+ const char* freqstr = strchr(line, ':');
+ if (freqstr) {
+ cpuinfo_cycles_per_second = strtod(freqstr+1, &err) * 1000000.0;
+ if (freqstr[1] != '\0' && *err == '\0' && cpuinfo_cycles_per_second > 0)
+ saw_mhz = true;
+ }
+ } else if (strncasecmp(line, "bogomips", sizeof("bogomips")-1) == 0) {
+ const char* freqstr = strchr(line, ':');
+ if (freqstr) {
+ bogo_clock = strtod(freqstr+1, &err) * 1000000.0;
+ if (freqstr[1] != '\0' && *err == '\0' && bogo_clock > 0)
+ saw_bogo = true;
+ }
+ } else if (strncasecmp(line, "processor", sizeof("processor")-1) == 0) {
+ num_cpus++; // count up every time we see an "processor :" entry
+ const char* freqstr = strchr(line, ':');
+ if (freqstr) {
+ const int cpu_id = strtol(freqstr+1, &err, 10);
+ if (freqstr[1] != '\0' && *err == '\0' && max_cpu_id < cpu_id)
+ max_cpu_id = cpu_id;
+ }
+ }
+ } while (chars_read > 0);
+ close(fd);
+
+ if (!saw_mhz) {
+ if (saw_bogo) {
+ // If we didn't find anything better, we'll use bogomips, but
+ // we're not happy about it.
+ cpuinfo_cycles_per_second = bogo_clock;
+ } else {
+ // If we don't even have bogomips, we'll use the slow estimation.
+ cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
+ }
+ }
+ if (num_cpus == 0) {
+ fprintf(stderr, "Failed to read num. CPUs correctly from /proc/cpuinfo\n");
+ } else {
+ if ((max_cpu_id + 1) != num_cpus) {
+ fprintf(stderr,
+ "CPU ID assignments in /proc/cpuinfo seems messed up."
+ " This is usually caused by a bad BIOS.\n");
+ }
+ cpuinfo_num_cpus = num_cpus;
+ }
+
+#elif defined OS_FREEBSD
+ // For this sysctl to work, the machine must be configured without
+ // SMP, APIC, or APM support. hz should be 64-bit in freebsd 7.0
+ // and later. Before that, it's a 32-bit quantity (and gives the
+ // wrong answer on machines faster than 2^32 Hz). See
+ // http://lists.freebsd.org/pipermail/freebsd-i386/2004-November/001846.html
+ // But also compare FreeBSD 7.0:
+ // http://fxr.watson.org/fxr/source/i386/i386/tsc.c?v=RELENG70#L223
+ // 231 error = sysctl_handle_quad(oidp, &freq, 0, req);
+ // To FreeBSD 6.3 (it's the same in 6-STABLE):
+ // http://fxr.watson.org/fxr/source/i386/i386/tsc.c?v=RELENG6#L131
+ // 139 error = sysctl_handle_int(oidp, &freq, sizeof(freq), req);
+#if __FreeBSD__ >= 7
+ uint64_t hz = 0;
+#else
+ unsigned int hz = 0;
+#endif
+ size_t sz = sizeof(hz);
+ const char *sysctl_path = "machdep.tsc_freq";
+ if ( sysctlbyname(sysctl_path, &hz, &sz, NULL, 0) != 0 ) {
+ fprintf(stderr, "Unable to determine clock rate from sysctl: %s: %s\n",
+ sysctl_path, strerror(errno));
+ cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
+ } else {
+ cpuinfo_cycles_per_second = hz;
+ }
+ // TODO: also figure out cpuinfo_num_cpus
+
+#elif defined OS_WINDOWS
+# pragma comment(lib, "shlwapi.lib") // for SHGetValue()
+ // In NT, read MHz from the registry. If we fail to do so or we're in win9x
+ // then make a crude estimate.
+ OSVERSIONINFO os;
+ os.dwOSVersionInfoSize = sizeof(os);
+ DWORD data, data_size = sizeof(data);
+ if (GetVersionEx(&os) &&
+ os.dwPlatformId == VER_PLATFORM_WIN32_NT &&
+ SUCCEEDED(SHGetValueA(HKEY_LOCAL_MACHINE,
+ "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0",
+ "~MHz", NULL, &data, &data_size)))
+ cpuinfo_cycles_per_second = (int64)data * (int64)(1000 * 1000); // was mhz
+ else
+ cpuinfo_cycles_per_second = EstimateCyclesPerSecond(500); // TODO <500?
+ // TODO: also figure out cpuinfo_num_cpus
+
+#elif defined OS_MACOSX
+ // returning "mach time units" per second. the current number of elapsed
+ // mach time units can be found by calling uint64 mach_absolute_time();
+ // while not as precise as actual CPU cycles, it is accurate in the face
+ // of CPU frequency scaling and multi-cpu/core machines.
+ // Our mac users have these types of machines, and accuracy
+ // (i.e. correctness) trumps precision.
+ // See cycleclock.h: CycleClock::Now(), which returns number of mach time
+ // units on Mac OS X.
+ mach_timebase_info_data_t timebase_info;
+ mach_timebase_info(&timebase_info);
+ double mach_time_units_per_nanosecond =
+ static_cast<double>(timebase_info.denom) /
+ static_cast<double>(timebase_info.numer);
+ cpuinfo_cycles_per_second = mach_time_units_per_nanosecond * 1e9;
+
+ int num_cpus = 0;
+ size_t size = sizeof(num_cpus);
+ int numcpus_name[] = { CTL_HW, HW_NCPU };
+ if (::sysctl(numcpus_name, arraysize(numcpus_name), &num_cpus, &size, 0, 0)
+ == 0
+ && (size == sizeof(num_cpus)))
+ cpuinfo_num_cpus = num_cpus;
+
+#else
+ // Generic cycles per second counter
+ cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
+#endif
+}
+} // end namespace
+
+#ifndef OS_WINDOWS
+// getrusage() based implementation of MyCPUUsage
+static double MyCPUUsageRUsage() {
+ struct rusage ru;
+ if (getrusage(RUSAGE_SELF, &ru) == 0) {
+ return (static_cast<double>(ru.ru_utime.tv_sec) +
+ static_cast<double>(ru.ru_utime.tv_usec)*1e-6 +
+ static_cast<double>(ru.ru_stime.tv_sec) +
+ static_cast<double>(ru.ru_stime.tv_usec)*1e-6);
+ } else {
+ return 0.0;
+ }
+}
+
+static bool MyCPUUsageCPUTimeNsLocked(double *cputime) {
+ static int cputime_fd = -1;
+ if (cputime_fd == -1) {
+ cputime_fd = open("/proc/self/cputime_ns", O_RDONLY);
+ if (cputime_fd < 0) {
+ cputime_fd = -1;
+ return false;
+ }
+ }
+ char buff[64];
+ memset(buff, 0, sizeof(buff));
+ if (pread(cputime_fd, buff, sizeof(buff)-1, 0) <= 0) {
+ close(cputime_fd);
+ cputime_fd = -1;
+ return false;
+ }
+ unsigned long long result = strtoull(buff, NULL, 0);
+ if (result == (std::numeric_limits<unsigned long long>::max)()) {
+ close(cputime_fd);
+ cputime_fd = -1;
+ return false;
+ }
+ *cputime = static_cast<double>(result) / 1e9;
+ return true;
+}
+
+double MyCPUUsage() {
+ {
+ mutex_lock l(&cputimens_mutex);
+ static bool use_cputime_ns = true;
+ if (use_cputime_ns) {
+ double value;
+ if (MyCPUUsageCPUTimeNsLocked(&value)) {
+ return value;
+ }
+ // Once MyCPUUsageCPUTimeNsLocked fails once fall back to getrusage().
+ std::cout << "Reading /proc/self/cputime_ns failed. Using getrusage().\n";
+ use_cputime_ns = false;
+ }
+ }
+ return MyCPUUsageRUsage();
+}
+
+double ChildrenCPUUsage() {
+ struct rusage ru;
+ if (getrusage(RUSAGE_CHILDREN, &ru) == 0) {
+ return (static_cast<double>(ru.ru_utime.tv_sec) +
+ static_cast<double>(ru.ru_utime.tv_usec)*1e-6 +
+ static_cast<double>(ru.ru_stime.tv_sec) +
+ static_cast<double>(ru.ru_stime.tv_usec)*1e-6);
+ } else {
+ return 0.0;
+ }
+}
+#endif // OS_WINDOWS
+
+double CyclesPerSecond(void) {
+ pthread_once(&cpuinfo_init, &InitializeSystemInfo);
+ return cpuinfo_cycles_per_second;
+}
+
+int NumCPUs(void) {
+ pthread_once(&cpuinfo_init, &InitializeSystemInfo);
+ return cpuinfo_num_cpus;
+}
+
