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+Time Interpolators
+------------------
+
+Time interpolators are a base of time calculation between timer ticks and
+allow an accurate determination of time down to the accuracy of the time
+source in nanoseconds.
+
+The architecture specific code typically provides gettimeofday and
+settimeofday under Linux. The time interpolator provides both if an arch
+defines CONFIG_TIME_INTERPOLATION. The arch still must set up timer tick
+operations and call the necessary functions to advance the clock.
+
+With the time interpolator a standardized interface exists for time
+interpolation between ticks. The provided logic is highly scalable
+and has been tested in SMP situations of up to 512 CPUs.
+
+If CONFIG_TIME_INTERPOLATION is defined then the architecture specific code
+(or the device drivers - like HPET) may register time interpolators.
+These are typically defined in the following way:
+
+static struct time_interpolator my_interpolator {
+        .frequency = MY_FREQUENCY,
+        .source = TIME_SOURCE_MMIO32,
+        .shift = 8,             /* scaling for higher accuracy */
+        .drift = -1,            /* Unknown drift */
+        .jitter = 0             /* time source is stable */
+};
+
+void time_init(void)
+{
+        ....
+        /* Initialization of the timer *.
+        my_interpolator.address = &my_timer;
+        register_time_interpolator(&my_interpolator);
+        ....
+}
+
+For more details see include/linux/timex.h and kernel/timer.c.
+
+Christoph Lameter <christoph@lameter.com>, October 31, 2004
+