Cache xtime every call to update_wall_time

[mirror_ubuntu-eoan-kernel.git] / kernel / time / timekeeping.c

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 07a3f1420c27fa06fedf7d18e7a33e7b99aa2c03..acc417b5a9b7786de60d124fc66b2dc5eb1c2111 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -47,10 +47,22 @@ EXPORT_SYMBOL(xtime_lock);
 struct timespec xtime __attribute__ ((aligned (16)));
 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
 static unsigned long total_sleep_time;         /* seconds */
-
 EXPORT_SYMBOL(xtime);
 
 
+#ifdef CONFIG_NO_HZ
+static struct timespec xtime_cache __attribute__ ((aligned (16)));
+static inline void update_xtime_cache(u64 nsec)
+{
+       xtime_cache = xtime;
+       timespec_add_ns(&xtime_cache, nsec);
+}
+#else
+#define xtime_cache xtime
+/* We do *not* want to evaluate the argument for this case */
+#define update_xtime_cache(n) do { } while (0)
+#endif
+
 static struct clocksource *clock; /* pointer to current clocksource */
 
 
@@ -478,6 +490,8 @@ void update_wall_time(void)
        xtime.tv_nsec = (s64)clock->xtime_nsec >> clock->shift;
        clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
 
+       update_xtime_cache(cyc2ns(clock, offset));
+
        /* check to see if there is a new clocksource to use */
        change_clocksource();
        update_vsyscall(&xtime, clock);
@@ -510,6 +524,13 @@ void monotonic_to_bootbased(struct timespec *ts)
        ts->tv_sec += total_sleep_time;
 }
 
+unsigned long get_seconds(void)
+{
+       return xtime_cache.tv_sec;
+}
+EXPORT_SYMBOL(get_seconds);
+
+
 struct timespec current_kernel_time(void)
 {
        struct timespec now;
@@ -518,10 +539,9 @@ struct timespec current_kernel_time(void)
        do {
                seq = read_seqbegin(&xtime_lock);
 
-               now = xtime;
+               now = xtime_cache;
        } while (read_seqretry(&xtime_lock, seq));
 
        return now;
 }
-
 EXPORT_SYMBOL(current_kernel_time);