gettime: drop tv_valid->last_cycles and tv_valid->last_tv_valid
[fio.git] / gettime.c
index 9f23e3fff526e0611df0dd1c9d6dc1b62d059916..6a50ec548d0091d0f489fb45c6310254539ed7f2 100644 (file)
--- a/gettime.c
+++ b/gettime.c
 #include "smalloc.h"
 
 #include "hash.h"
+#include "os/os.h"
+
+#if defined(ARCH_HAVE_CPU_CLOCK)
+#ifndef ARCH_CPU_CLOCK_CYCLES_PER_USEC
+static unsigned long cycles_per_msec;
+static unsigned long long cycles_start;
+static unsigned long long clock_mult;
+static unsigned long long max_cycles_mask;
+static unsigned long long nsecs_for_max_cycles;
+static unsigned int clock_shift;
+static unsigned int max_cycles_shift;
+#define MAX_CLOCK_SEC 60*60
+#endif
+#ifdef ARCH_CPU_CLOCK_WRAPS
+static unsigned int cycles_wrap;
+#endif
+#endif
+int tsc_reliable = 0;
 
+struct tv_valid {
+       int warned;
+};
 #ifdef ARCH_HAVE_CPU_CLOCK
-static unsigned long cycles_per_usec;
-static unsigned long last_cycles;
-int tsc_reliable = 0;
+#ifdef CONFIG_TLS_THREAD
+static __thread struct tv_valid static_tv_valid;
+#else
+static pthread_key_t tv_tls_key;
+#endif
 #endif
-static struct timeval last_tv;
-static int last_tv_valid;
 
 enum fio_cs fio_clock_source = FIO_PREFERRED_CLOCK_SOURCE;
 int fio_clock_source_set = 0;
-enum fio_cs fio_clock_source_inited = CS_INVAL;
+static enum fio_cs fio_clock_source_inited = CS_INVAL;
 
 #ifdef FIO_DEBUG_TIME
 
@@ -54,7 +75,7 @@ static struct gtod_log *find_hash(void *caller)
        return NULL;
 }
 
-static struct gtod_log *find_log(void *caller)
+static void inc_caller(void *caller)
 {
        struct gtod_log *log = find_hash(caller);
 
@@ -70,16 +91,13 @@ static struct gtod_log *find_log(void *caller)
                flist_add_tail(&log->list, &hash[h]);
        }
 
-       return log;
+       log->calls++;
 }
 
 static void gtod_log_caller(void *caller)
 {
-       if (gtod_inited) {
-               struct gtod_log *log = find_log(caller);
-
-               log->calls++;
-       }
+       if (gtod_inited)
+               inc_caller(caller);
 }
 
 static void fio_exit fio_dump_gtod(void)
@@ -115,57 +133,71 @@ static void fio_init gtod_init(void)
 
 #endif /* FIO_DEBUG_TIME */
 
-#ifdef FIO_DEBUG_TIME
-void fio_gettime(struct timeval *tp, void *caller)
+#ifdef CONFIG_CLOCK_GETTIME
+static int fill_clock_gettime(struct timespec *ts)
+{
+#if defined(CONFIG_CLOCK_MONOTONIC_RAW)
+       return clock_gettime(CLOCK_MONOTONIC_RAW, ts);
+#elif defined(CONFIG_CLOCK_MONOTONIC)
+       return clock_gettime(CLOCK_MONOTONIC, ts);
 #else
-void fio_gettime(struct timeval *tp, void fio_unused *caller)
+       return clock_gettime(CLOCK_REALTIME, ts);
 #endif
-{
-#ifdef FIO_DEBUG_TIME
-       if (!caller)
-               caller = __builtin_return_address(0);
-
-       gtod_log_caller(caller);
+}
 #endif
-       if (fio_tv) {
-               memcpy(tp, fio_tv, sizeof(*tp));
-               return;
-       }
 
+static void __fio_gettime(struct timespec *tp)
+{
        switch (fio_clock_source) {
-       case CS_GTOD:
-               gettimeofday(tp, NULL);
-               break;
-       case CS_CGETTIME: {
-               struct timespec ts;
+#ifdef CONFIG_GETTIMEOFDAY
+       case CS_GTOD: {
+               struct timeval tv;
+               gettimeofday(&tv, NULL);
 
-#ifdef FIO_HAVE_CLOCK_MONOTONIC
-               if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0) {
-#else
-               if (clock_gettime(CLOCK_REALTIME, &ts) < 0) {
+               tp->tv_sec = tv.tv_sec;
+               tp->tv_nsec = tv.tv_usec * 1000;
+               break;
+               }
 #endif
+#ifdef CONFIG_CLOCK_GETTIME
+       case CS_CGETTIME: {
+               if (fill_clock_gettime(tp) < 0) {
                        log_err("fio: clock_gettime fails\n");
                        assert(0);
                }
-
-               tp->tv_sec = ts.tv_sec;
-               tp->tv_usec = ts.tv_nsec / 1000;
                break;
                }
+#endif
 #ifdef ARCH_HAVE_CPU_CLOCK
        case CS_CPUCLOCK: {
-               unsigned long long usecs, t;
+               uint64_t nsecs, t, multiples;
+               struct tv_valid *tv;
+
+#ifdef CONFIG_TLS_THREAD
+               tv = &static_tv_valid;
+#else
+               tv = pthread_getspecific(tv_tls_key);
+#endif
 
                t = get_cpu_clock();
-               if (t < last_cycles) {
-                       dprint(FD_TIME, "CPU clock going back in time\n");
-                       t = last_cycles;
+#ifdef ARCH_CPU_CLOCK_WRAPS
+               if (t < cycles_start && !cycles_wrap)
+                       cycles_wrap = 1;
+               else if (cycles_wrap && t >= cycles_start && !tv->warned) {
+                       log_err("fio: double CPU clock wrap\n");
+                       tv->warned = 1;
                }
-
-               usecs = t / cycles_per_usec;
-               tp->tv_sec = usecs / 1000000;
-               tp->tv_usec = usecs % 1000000;
-               last_cycles = t;
+#endif
+#ifdef ARCH_CPU_CLOCK_CYCLES_PER_USEC
+               nsecs = t / ARCH_CPU_CLOCK_CYCLES_PER_USEC * 1000;
+#else
+               t -= cycles_start;
+               multiples = t >> max_cycles_shift;
+               nsecs = multiples * nsecs_for_max_cycles;
+               nsecs += ((t & max_cycles_mask) * clock_mult) >> clock_shift;
+#endif
+               tp->tv_sec = nsecs / 1000000000ULL;
+               tp->tv_nsec = nsecs % 1000000000ULL;
                break;
                }
 #endif
@@ -173,34 +205,45 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
                log_err("fio: invalid clock source %d\n", fio_clock_source);
                break;
        }
+}
 
-       /*
-        * If Linux is using the tsc clock on non-synced processors,
-        * sometimes time can appear to drift backwards. Fix that up.
-        */
-       if (last_tv_valid) {
-               if (tp->tv_sec < last_tv.tv_sec)
-                       tp->tv_sec = last_tv.tv_sec;
-               else if (last_tv.tv_sec == tp->tv_sec &&
-                        tp->tv_usec < last_tv.tv_usec)
-                       tp->tv_usec = last_tv.tv_usec;
-       }
-       last_tv_valid = 1;
-       memcpy(&last_tv, tp, sizeof(*tp));
+#ifdef FIO_DEBUG_TIME
+void fio_gettime(struct timespec *tp, void *caller)
+#else
+void fio_gettime(struct timespec *tp, void fio_unused *caller)
+#endif
+{
+#ifdef FIO_DEBUG_TIME
+       if (!caller)
+               caller = __builtin_return_address(0);
+
+       gtod_log_caller(caller);
+#endif
+       if (fio_unlikely(fio_gettime_offload(tp)))
+               return;
+
+       __fio_gettime(tp);
 }
 
-#ifdef ARCH_HAVE_CPU_CLOCK
-static unsigned long get_cycles_per_usec(void)
+#if defined(ARCH_HAVE_CPU_CLOCK) && !defined(ARCH_CPU_CLOCK_CYCLES_PER_USEC)
+static unsigned long get_cycles_per_msec(void)
 {
-       struct timeval s, e;
-       unsigned long long c_s, c_e;
+       struct timespec s, e;
+       uint64_t c_s, c_e;
+       enum fio_cs old_cs = fio_clock_source;
+       uint64_t elapsed;
+
+#ifdef CONFIG_CLOCK_GETTIME
+       fio_clock_source = CS_CGETTIME;
+#else
+       fio_clock_source = CS_GTOD;
+#endif
+       __fio_gettime(&s);
 
-       gettimeofday(&s, NULL);
        c_s = get_cpu_clock();
        do {
-               unsigned long long elapsed;
+               __fio_gettime(&e);
 
-               gettimeofday(&e, NULL);
                elapsed = utime_since(&s, &e);
                if (elapsed >= 1280) {
                        c_e = get_cpu_clock();
@@ -208,21 +251,23 @@ static unsigned long get_cycles_per_usec(void)
                }
        } while (1);
 
-       return (c_e - c_s + 127) >> 7;
+       fio_clock_source = old_cs;
+       return (c_e - c_s) * 1000 / elapsed;
 }
 
 #define NR_TIME_ITERS  50
 
-static void calibrate_cpu_clock(void)
+static int calibrate_cpu_clock(void)
 {
        double delta, mean, S;
-       unsigned long avg, cycles[NR_TIME_ITERS];
-       int i, samples;
+       uint64_t minc, maxc, avg, cycles[NR_TIME_ITERS];
+       int i, samples, sft = 0;
+       unsigned long long tmp, max_ticks, max_mult;
 
-       cycles[0] = get_cycles_per_usec();
+       cycles[0] = get_cycles_per_msec();
        S = delta = mean = 0.0;
        for (i = 0; i < NR_TIME_ITERS; i++) {
-               cycles[i] = get_cycles_per_usec();
+               cycles[i] = get_cycles_per_msec();
                delta = cycles[i] - mean;
                if (delta) {
                        mean += delta / (i + 1.0);
@@ -230,12 +275,23 @@ static void calibrate_cpu_clock(void)
                }
        }
 
+       /*
+        * The most common platform clock breakage is returning zero
+        * indefinitely. Check for that and return failure.
+        */
+       if (!cycles[0] && !cycles[NR_TIME_ITERS - 1])
+               return 1;
+
        S = sqrt(S / (NR_TIME_ITERS - 1.0));
 
-       samples = avg = 0;
+       minc = -1ULL;
+       maxc = samples = avg = 0;
        for (i = 0; i < NR_TIME_ITERS; i++) {
                double this = cycles[i];
 
+               minc = min(cycles[i], minc);
+               maxc = max(cycles[i], maxc);
+
                if ((fmax(this, mean) - fmin(this, mean)) > S)
                        continue;
                samples++;
@@ -243,20 +299,91 @@ static void calibrate_cpu_clock(void)
        }
 
        S /= (double) NR_TIME_ITERS;
-       mean /= 10.0;
 
        for (i = 0; i < NR_TIME_ITERS; i++)
-               dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
+               dprint(FD_TIME, "cycles[%d]=%llu\n", i, (unsigned long long) cycles[i]);
 
        avg /= samples;
-       avg = (avg + 9) / 10;
-       dprint(FD_TIME, "avg: %lu\n", avg);
-       dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
+       cycles_per_msec = avg;
+       dprint(FD_TIME, "avg: %llu\n", (unsigned long long) avg);
+       dprint(FD_TIME, "min=%llu, max=%llu, mean=%f, S=%f\n",
+                       (unsigned long long) minc,
+                       (unsigned long long) maxc, mean, S);
+
+       max_ticks = MAX_CLOCK_SEC * cycles_per_msec * 1000ULL;
+        max_mult = ULLONG_MAX / max_ticks;
+        dprint(FD_TIME, "\n\nmax_ticks=%llu, __builtin_clzll=%d, max_mult=%llu\n",
+               max_ticks, __builtin_clzll(max_ticks), max_mult);
+
+        /*
+         * Find the largest shift count that will produce
+         * a multiplier that does not exceed max_mult
+         */
+        tmp = max_mult * cycles_per_msec / 1000000;
+        while (tmp > 1) {
+                tmp >>= 1;
+                sft++;
+                dprint(FD_TIME, "tmp=%llu, sft=%u\n", tmp, sft);
+        }
+
+        clock_shift = sft;
+        clock_mult = (1ULL << sft) * 1000000 / cycles_per_msec;
+       dprint(FD_TIME, "clock_shift=%u, clock_mult=%llu\n", clock_shift, clock_mult);
+
+       // Find the greatest power of 2 clock ticks that is less than the ticks in MAX_CLOCK_SEC_2STAGE
+       max_cycles_shift = max_cycles_mask = 0;
+       tmp = MAX_CLOCK_SEC * 1000ULL * cycles_per_msec;
+       dprint(FD_TIME, "tmp=%llu, max_cycles_shift=%u\n", tmp, max_cycles_shift);
+       while (tmp > 1) {
+               tmp >>= 1;
+               max_cycles_shift++;
+               dprint(FD_TIME, "tmp=%llu, max_cycles_shift=%u\n", tmp, max_cycles_shift);
+       }
+       // if use use (1ULL << max_cycles_shift) * 1000 / cycles_per_msec here we will
+       // have a discontinuity every (1ULL << max_cycles_shift) cycles
+       nsecs_for_max_cycles = ((1ULL << max_cycles_shift) * clock_mult) >> clock_shift;
 
-       cycles_per_usec = avg;
+       // Use a bitmask to calculate ticks % (1ULL << max_cycles_shift)
+       for (tmp = 0; tmp < max_cycles_shift; tmp++)
+               max_cycles_mask |= 1ULL << tmp;
+
+       dprint(FD_TIME, "max_cycles_shift=%u, 2^max_cycles_shift=%llu, nsecs_for_max_cycles=%llu, max_cycles_mask=%016llx\n",
+               max_cycles_shift, (1ULL << max_cycles_shift),
+               nsecs_for_max_cycles, max_cycles_mask);
+
+       cycles_start = get_cpu_clock();
+       dprint(FD_TIME, "cycles_start=%llu\n", cycles_start);
+       return 0;
 }
 #else
-static void calibrate_cpu_clock(void)
+static int calibrate_cpu_clock(void)
+{
+#ifdef ARCH_CPU_CLOCK_CYCLES_PER_USEC
+       return 0;
+#else
+       return 1;
+#endif
+}
+#endif // ARCH_HAVE_CPU_CLOCK
+
+#ifndef CONFIG_TLS_THREAD
+void fio_local_clock_init(int is_thread)
+{
+       struct tv_valid *t;
+
+       t = calloc(1, sizeof(*t));
+       if (pthread_setspecific(tv_tls_key, t)) {
+               log_err("fio: can't set TLS key\n");
+               assert(0);
+       }
+}
+
+static void kill_tv_tls_key(void *data)
+{
+       free(data);
+}
+#else
+void fio_local_clock_init(int is_thread)
 {
 }
 #endif
@@ -266,9 +393,15 @@ void fio_clock_init(void)
        if (fio_clock_source == fio_clock_source_inited)
                return;
 
-       last_tv_valid = 0;
+#ifndef CONFIG_TLS_THREAD
+       if (pthread_key_create(&tv_tls_key, kill_tv_tls_key))
+               log_err("fio: can't create TLS key\n");
+#endif
+
        fio_clock_source_inited = fio_clock_source;
-       calibrate_cpu_clock();
+
+       if (calibrate_cpu_clock())
+               tsc_reliable = 0;
 
        /*
         * If the arch sets tsc_reliable != 0, then it must be good enough
@@ -276,19 +409,38 @@ void fio_clock_init(void)
         * runs at a constant rate and is synced across CPU cores.
         */
        if (tsc_reliable) {
-               if (!fio_clock_source_set)
+               if (!fio_clock_source_set && !fio_monotonic_clocktest(0))
                        fio_clock_source = CS_CPUCLOCK;
        } else if (fio_clock_source == CS_CPUCLOCK)
                log_info("fio: clocksource=cpu may not be reliable\n");
 }
 
-unsigned long long utime_since(struct timeval *s, struct timeval *e)
+uint64_t ntime_since(const struct timespec *s, const struct timespec *e)
 {
-       long sec, usec;
-       unsigned long long ret;
+       int64_t sec, nsec;
+
+       sec = e->tv_sec - s->tv_sec;
+       nsec = e->tv_nsec - s->tv_nsec;
+       if (sec > 0 && nsec < 0) {
+              sec--;
+              nsec += 1000000000LL;
+       }
+
+       /*
+       * time warp bug on some kernels?
+       */
+       if (sec < 0 || (sec == 0 && nsec < 0))
+              return 0;
+
+       return nsec + (sec * 1000000000LL);
+}
+
+uint64_t utime_since(const struct timespec *s, const struct timespec *e)
+{
+       int64_t sec, usec;
 
        sec = e->tv_sec - s->tv_sec;
-       usec = e->tv_usec - s->tv_usec;
+       usec = (e->tv_nsec - s->tv_nsec) / 1000;
        if (sec > 0 && usec < 0) {
                sec--;
                usec += 1000000;
@@ -300,25 +452,29 @@ unsigned long long utime_since(struct timeval *s, struct timeval *e)
        if (sec < 0 || (sec == 0 && usec < 0))
                return 0;
 
-       ret = sec * 1000000ULL + usec;
-
-       return ret;
+       return usec + (sec * 1000000);
 }
 
-unsigned long long utime_since_now(struct timeval *s)
+uint64_t utime_since_now(const struct timespec *s)
 {
-       struct timeval t;
+       struct timespec t;
+#ifdef FIO_DEBUG_TIME
+       void *p = __builtin_return_address(0);
 
+       fio_gettime(&t, p);
+#else
        fio_gettime(&t, NULL);
+#endif
+
        return utime_since(s, &t);
 }
 
-unsigned long mtime_since(struct timeval *s, struct timeval *e)
+uint64_t mtime_since_tv(const struct timeval *s, const struct timeval *e)
 {
-       long sec, usec, ret;
+       int64_t sec, usec;
 
        sec = e->tv_sec - s->tv_sec;
-       usec = e->tv_usec - s->tv_usec;
+       usec = (e->tv_usec - s->tv_usec);
        if (sec > 0 && usec < 0) {
                sec--;
                usec += 1000000;
@@ -327,23 +483,287 @@ unsigned long mtime_since(struct timeval *s, struct timeval *e)
        if (sec < 0 || (sec == 0 && usec < 0))
                return 0;
 
-       sec *= 1000UL;
-       usec /= 1000UL;
-       ret = sec + usec;
-
-       return ret;
+       sec *= 1000;
+       usec /= 1000;
+       return sec + usec;
 }
 
-unsigned long mtime_since_now(struct timeval *s)
+uint64_t mtime_since_now(const struct timespec *s)
 {
-       struct timeval t;
+       struct timespec t;
+#ifdef FIO_DEBUG_TIME
        void *p = __builtin_return_address(0);
 
        fio_gettime(&t, p);
+#else
+       fio_gettime(&t, NULL);
+#endif
+
        return mtime_since(s, &t);
 }
 
-unsigned long time_since_now(struct timeval *s)
+uint64_t mtime_since(const struct timespec *s, const struct timespec *e)
+{
+       int64_t sec, usec;
+
+       sec = e->tv_sec - s->tv_sec;
+       usec = (e->tv_nsec - s->tv_nsec) / 1000;
+       if (sec > 0 && usec < 0) {
+               sec--;
+               usec += 1000000;
+       }
+
+       if (sec < 0 || (sec == 0 && usec < 0))
+               return 0;
+
+       sec *= 1000;
+       usec /= 1000;
+       return sec + usec;
+}
+
+uint64_t time_since_now(const struct timespec *s)
 {
        return mtime_since_now(s) / 1000;
 }
+
+#if defined(FIO_HAVE_CPU_AFFINITY) && defined(ARCH_HAVE_CPU_CLOCK)  && \
+    defined(CONFIG_SFAA)
+
+#define CLOCK_ENTRIES_DEBUG    100000
+#define CLOCK_ENTRIES_TEST     10000
+
+struct clock_entry {
+       uint32_t seq;
+       uint32_t cpu;
+       uint64_t tsc;
+};
+
+struct clock_thread {
+       pthread_t thread;
+       int cpu;
+       int debug;
+       pthread_mutex_t lock;
+       pthread_mutex_t started;
+       unsigned long nr_entries;
+       uint32_t *seq;
+       struct clock_entry *entries;
+};
+
+static inline uint32_t atomic32_inc_return(uint32_t *seq)
+{
+       return 1 + __sync_fetch_and_add(seq, 1);
+}
+
+static void *clock_thread_fn(void *data)
+{
+       struct clock_thread *t = data;
+       struct clock_entry *c;
+       os_cpu_mask_t cpu_mask;
+       uint32_t last_seq;
+       unsigned long long first;
+       int i;
+
+       if (fio_cpuset_init(&cpu_mask)) {
+               int __err = errno;
+
+               log_err("clock cpuset init failed: %s\n", strerror(__err));
+               goto err_out;
+       }
+
+       fio_cpu_set(&cpu_mask, t->cpu);
+
+       if (fio_setaffinity(gettid(), cpu_mask) == -1) {
+               int __err = errno;
+
+               log_err("clock setaffinity failed: %s\n", strerror(__err));
+               goto err;
+       }
+
+       pthread_mutex_lock(&t->lock);
+       pthread_mutex_unlock(&t->started);
+
+       first = get_cpu_clock();
+       last_seq = 0;
+       c = &t->entries[0];
+       for (i = 0; i < t->nr_entries; i++, c++) {
+               uint32_t seq;
+               uint64_t tsc;
+
+               c->cpu = t->cpu;
+               do {
+                       seq = atomic32_inc_return(t->seq);
+                       if (seq < last_seq)
+                               break;
+                       tsc = get_cpu_clock();
+               } while (seq != *t->seq);
+
+               c->seq = seq;
+               c->tsc = tsc;
+       }
+
+       if (t->debug) {
+               unsigned long long clocks;
+
+               clocks = t->entries[i - 1].tsc - t->entries[0].tsc;
+               log_info("cs: cpu%3d: %llu clocks seen, first %llu\n", t->cpu,
+                                                       clocks, first);
+       }
+
+       /*
+        * The most common platform clock breakage is returning zero
+        * indefinitely. Check for that and return failure.
+        */
+       if (!t->entries[i - 1].tsc && !t->entries[0].tsc)
+               goto err;
+
+       fio_cpuset_exit(&cpu_mask);
+       return NULL;
+err:
+       fio_cpuset_exit(&cpu_mask);
+err_out:
+       return (void *) 1;
+}
+
+static int clock_cmp(const void *p1, const void *p2)
+{
+       const struct clock_entry *c1 = p1;
+       const struct clock_entry *c2 = p2;
+
+       if (c1->seq == c2->seq)
+               log_err("cs: bug in atomic sequence!\n");
+
+       return c1->seq - c2->seq;
+}
+
+int fio_monotonic_clocktest(int debug)
+{
+       struct clock_thread *cthreads;
+       unsigned int nr_cpus = cpus_online();
+       struct clock_entry *entries;
+       unsigned long nr_entries, tentries, failed = 0;
+       struct clock_entry *prev, *this;
+       uint32_t seq = 0;
+       unsigned int i;
+
+       if (debug) {
+               log_info("cs: reliable_tsc: %s\n", tsc_reliable ? "yes" : "no");
+
+#ifdef FIO_INC_DEBUG
+               fio_debug |= 1U << FD_TIME;
+#endif
+               nr_entries = CLOCK_ENTRIES_DEBUG;
+       } else
+               nr_entries = CLOCK_ENTRIES_TEST;
+
+       calibrate_cpu_clock();
+
+       if (debug) {
+#ifdef FIO_INC_DEBUG
+               fio_debug &= ~(1U << FD_TIME);
+#endif
+       }
+
+       cthreads = malloc(nr_cpus * sizeof(struct clock_thread));
+       tentries = nr_entries * nr_cpus;
+       entries = malloc(tentries * sizeof(struct clock_entry));
+
+       if (debug)
+               log_info("cs: Testing %u CPUs\n", nr_cpus);
+
+       for (i = 0; i < nr_cpus; i++) {
+               struct clock_thread *t = &cthreads[i];
+
+               t->cpu = i;
+               t->debug = debug;
+               t->seq = &seq;
+               t->nr_entries = nr_entries;
+               t->entries = &entries[i * nr_entries];
+               pthread_mutex_init(&t->lock, NULL);
+               pthread_mutex_init(&t->started, NULL);
+               pthread_mutex_lock(&t->lock);
+               if (pthread_create(&t->thread, NULL, clock_thread_fn, t)) {
+                       failed++;
+                       nr_cpus = i;
+                       break;
+               }
+       }
+
+       for (i = 0; i < nr_cpus; i++) {
+               struct clock_thread *t = &cthreads[i];
+
+               pthread_mutex_lock(&t->started);
+       }
+
+       for (i = 0; i < nr_cpus; i++) {
+               struct clock_thread *t = &cthreads[i];
+
+               pthread_mutex_unlock(&t->lock);
+       }
+
+       for (i = 0; i < nr_cpus; i++) {
+               struct clock_thread *t = &cthreads[i];
+               void *ret;
+
+               pthread_join(t->thread, &ret);
+               if (ret)
+                       failed++;
+       }
+       free(cthreads);
+
+       if (failed) {
+               if (debug)
+                       log_err("Clocksource test: %lu threads failed\n", failed);
+               goto err;
+       }
+
+       qsort(entries, tentries, sizeof(struct clock_entry), clock_cmp);
+
+       /* silence silly gcc */
+       prev = NULL;
+       for (failed = i = 0; i < tentries; i++) {
+               this = &entries[i];
+
+               if (!i) {
+                       prev = this;
+                       continue;
+               }
+
+               if (prev->tsc > this->tsc) {
+                       uint64_t diff = prev->tsc - this->tsc;
+
+                       if (!debug) {
+                               failed++;
+                               break;
+                       }
+
+                       log_info("cs: CPU clock mismatch (diff=%llu):\n",
+                                               (unsigned long long) diff);
+                       log_info("\t CPU%3u: TSC=%llu, SEQ=%u\n", prev->cpu, (unsigned long long) prev->tsc, prev->seq);
+                       log_info("\t CPU%3u: TSC=%llu, SEQ=%u\n", this->cpu, (unsigned long long) this->tsc, this->seq);
+                       failed++;
+               }
+
+               prev = this;
+       }
+
+       if (debug) {
+               if (failed)
+                       log_info("cs: Failed: %lu\n", failed);
+               else
+                       log_info("cs: Pass!\n");
+       }
+err:
+       free(entries);
+       return !!failed;
+}
+
+#else /* defined(FIO_HAVE_CPU_AFFINITY) && defined(ARCH_HAVE_CPU_CLOCK) */
+
+int fio_monotonic_clocktest(int debug)
+{
+       if (debug)
+               log_info("cs: current platform does not support CPU clocks\n");
+       return 1;
+}
+
+#endif