gettime: make last_cycles thread local too

Avoids a lot of cache line bouncing for threads.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/gettime.c b/gettime.c
index 921c171fdef80a414e8fdf039c9c09faefa30e02..248f14691a5b307c8ae17e4fc6b0111ae6e2c2ec 100644 (file)
--- a/gettime.c
+++ b/gettime.c
@@ -15,13 +15,13 @@
 
 #ifdef ARCH_HAVE_CPU_CLOCK
 static unsigned long cycles_per_usec;
-static unsigned long last_cycles;
 int tsc_reliable = 0;
 #endif
 
 struct tv_valid {
        struct timeval last_tv;
        int last_tv_valid;
+       unsigned long last_cycles;
 };
 static pthread_key_t tv_tls_key;
 
@@ -126,7 +126,7 @@ void fio_gettime(struct timeval *tp, void *caller)
 void fio_gettime(struct timeval *tp, void fio_unused *caller)
 #endif
 {
-       struct tv_valid *t;
+       struct tv_valid *tv;
 
 #ifdef FIO_DEBUG_TIME
        if (!caller)
@@ -139,6 +139,8 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
                return;
        }
 
+       tv = pthread_getspecific(tv_tls_key);
+
        switch (fio_clock_source) {
        case CS_GTOD:
                gettimeofday(tp, NULL);
@@ -164,15 +166,15 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
                unsigned long long usecs, t;
 
                t = get_cpu_clock();
-               if (t < last_cycles) {
+               if (tv && t < tv->last_cycles) {
                        dprint(FD_TIME, "CPU clock going back in time\n");
-                       t = last_cycles;
-               }
+                       t = tv->last_cycles;
+               } else if (tv)
+                       tv->last_cycles = t;
 
                usecs = t / cycles_per_usec;
                tp->tv_sec = usecs / 1000000;
                tp->tv_usec = usecs % 1000000;
-               last_cycles = t;
                break;
                }
 #endif
@@ -185,17 +187,16 @@ void fio_gettime(struct timeval *tp, void fio_unused *caller)
         * If Linux is using the tsc clock on non-synced processors,
         * sometimes time can appear to drift backwards. Fix that up.
         */
-       t = pthread_getspecific(tv_tls_key);
-       if (t) {
-               if (t->last_tv_valid) {
-                       if (tp->tv_sec < t->last_tv.tv_sec)
-                               tp->tv_sec = t->last_tv.tv_sec;
-                       else if (t->last_tv.tv_sec == tp->tv_sec &&
-                                tp->tv_usec < t->last_tv.tv_usec)
-                               tp->tv_usec = t->last_tv.tv_usec;
+       if (tv) {
+               if (tv->last_tv_valid) {
+                       if (tp->tv_sec < tv->last_tv.tv_sec)
+                               tp->tv_sec = tv->last_tv.tv_sec;
+                       else if (tv->last_tv.tv_sec == tp->tv_sec &&
+                                tp->tv_usec < tv->last_tv.tv_usec)
+                               tp->tv_usec = tv->last_tv.tv_usec;
                }
-               t->last_tv_valid = 1;
-               memcpy(&t->last_tv, tp, sizeof(*tp));
+               tv->last_tv_valid = 1;
+               memcpy(&tv->last_tv, tp, sizeof(*tp));
        }
 }