#include "platform.h"
#include "gnunet_load_lib.h"
-#define DEBUG_LOAD GNUNET_NO
+
+#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
/**
* Values we track for load calculations.
*/
-struct GNUNET_LOAD_Value
+struct GNUNET_LOAD_Value
{
+ /**
+ * How fast should the load decline if no values are added?
+ */
+ struct GNUNET_TIME_Relative autodecline;
+
+ /**
+ * Last time this load value was updated by an event.
+ */
+ struct GNUNET_TIME_Absolute last_update;
+
/**
* Sum of all datastore delays ever observed (in ms). Note that
* delays above 64k ms are excluded (to avoid overflow within
* first 4 billion requests).
*/
uint64_t cummulative_delay;
-
+
/**
* Sum of squares of all datastore delays ever observed (in ms). Note that
* delays above 64k ms are excluded (to avoid overflow within
* first 4 billion requests).
*/
uint64_t cummulative_squared_delay;
-
+
/**
* Total number of requests included in the cummulative datastore delay values.
*/
uint64_t cummulative_request_count;
-
+
/**
* Current running average datastore delay. Its relation to the
* average datastore delay and it std. dev. (as calcualted from the
};
+static void
+internal_update (struct GNUNET_LOAD_Value *load)
+{
+ struct GNUNET_TIME_Relative delta;
+ unsigned int n;
+
+ if (load->autodecline.rel_value == GNUNET_TIME_UNIT_FOREVER_REL.rel_value)
+ return;
+ delta = GNUNET_TIME_absolute_get_duration (load->last_update);
+ if (delta.rel_value < load->autodecline.rel_value)
+ return;
+ if (load->autodecline.rel_value == 0)
+ {
+ load->runavg_delay = 0.0;
+ load->load = 0;
+ return;
+ }
+ n = delta.rel_value / load->autodecline.rel_value;
+ if (n > 16)
+ {
+ load->runavg_delay = 0.0;
+ load->load = 0;
+ return;
+ }
+ while (n > 0)
+ {
+ n--;
+ load->runavg_delay = (load->runavg_delay * 7.0) / 8.0;
+ }
+}
+
+
/**
* Create a new load value.
*
+ * @param autodecline speed at which this value should automatically
+ * decline in the absence of external events; at the given
+ * frequency, 0-load values will be added to the load
* @return the new load value
*/
struct GNUNET_LOAD_Value *
-GNUNET_LOAD_value_init ()
+GNUNET_LOAD_value_init (struct GNUNET_TIME_Relative autodecline)
+{
+ struct GNUNET_LOAD_Value *ret;
+
+ ret = GNUNET_malloc (sizeof (struct GNUNET_LOAD_Value));
+ ret->autodecline = autodecline;
+ ret->last_update = GNUNET_TIME_absolute_get ();
+ return ret;
+}
+
+
+/**
+ * Change the value by which the load automatically declines.
+ *
+ * @param load load to update
+ * @param autodecline frequency of load decline
+ */
+void
+GNUNET_LOAD_value_set_decline (struct GNUNET_LOAD_Value *load,
+ struct GNUNET_TIME_Relative autodecline)
{
- return GNUNET_malloc (sizeof (struct GNUNET_LOAD_Value));
+ internal_update (load);
+ load->autodecline = autodecline;
+}
+
+
+/**
+ * Recalculate our load value.
+ *
+ * @param load load to update
+ */
+static void
+calculate_load (struct GNUNET_LOAD_Value *load)
+{
+ double stddev;
+ double avgdel;
+ double sum_val_i;
+ double n;
+ double nm1;
+
+ if (load->cummulative_request_count <= 1)
+ return;
+ /* calcuate std dev of latency; we have for n values of "i" that:
+ *
+ * avg = (sum val_i) / n
+ * stddev = (sum (val_i - avg)^2) / (n-1)
+ * = (sum (val_i^2 - 2 avg val_i + avg^2) / (n-1)
+ * = (sum (val_i^2) - 2 avg sum (val_i) + n * avg^2) / (n-1)
+ */
+ sum_val_i = (double) load->cummulative_delay;
+ n = ((double) load->cummulative_request_count);
+ nm1 = n - 1.0;
+ avgdel = sum_val_i / n;
+ stddev =
+ (((double) load->cummulative_squared_delay) - 2.0 * avgdel * sum_val_i +
+ n * avgdel * avgdel) / nm1;
+ if (stddev <= 0)
+ stddev = 0.01; /* must have been rounding error or zero; prevent division by zero */
+ /* now calculate load based on how far out we are from
+ * std dev; or if we are below average, simply assume load zero */
+ if (load->runavg_delay < avgdel)
+ load->load = 0.0;
+ else
+ load->load = (load->runavg_delay - avgdel) / stddev;
}
* that we could not do proper calculations
*/
double
-GNUNET_LOAD_get_load (const struct GNUNET_LOAD_Value *load)
+GNUNET_LOAD_get_load (struct GNUNET_LOAD_Value *load)
{
+ internal_update (load);
+ calculate_load (load);
return load->load;
}
* @return zero if update was never called
*/
double
-GNUNET_LOAD_get_average (const struct GNUNET_LOAD_Value *load)
+GNUNET_LOAD_get_average (struct GNUNET_LOAD_Value *load)
{
double n;
- double avg;
double sum_val_i;
+ internal_update (load);
if (load->cummulative_request_count == 0)
return 0.0;
n = ((double) load->cummulative_request_count);
* @param data latest measurement value (for example, delay)
*/
void
-GNUNET_LOAD_update (struct GNUNET_LOAD_Value *load,
- uint64_t data)
+GNUNET_LOAD_update (struct GNUNET_LOAD_Value *load, uint64_t data)
{
uint32_t dv;
- double stddev;
- double avgdel;
- double sum_val_i;
- double n;
- double nm1;
+ internal_update (load);
+ load->last_update = GNUNET_TIME_absolute_get ();
if (data > 64 * 1024)
- {
- /* very large */
- load->load = 100.0;
- return;
- }
+ {
+ /* very large */
+ load->load = 100.0;
+ return;
+ }
dv = (uint32_t) data;
load->cummulative_delay += dv;
- load->cummulative_squared_delay += dv * dv;
+ load->cummulative_squared_delay += dv * dv;
load->cummulative_request_count++;
load->runavg_delay = ((load->runavg_delay * 7.0) + dv) / 8.0;
- if (load->cummulative_request_count > 1)
- {
- /* calcuate std dev of latency; we have for n values of "i" that:
-
- avg = (sum val_i) / n
- stddev = (sum (val_i - avg)^2) / (n-1)
- = (sum (val_i^2 - 2 avg val_i + avg^2) / (n-1)
- = (sum (val_i^2) - 2 avg sum (val_i) + n * avg^2) / (n-1)
- */
- sum_val_i = (double) load->cummulative_delay;
- n = ((double) load->cummulative_request_count);
- nm1 = n - 1.0;
- avgdel = sum_val_i / n;
- stddev = (((double) load->cummulative_squared_delay) - 2.0 * avgdel * sum_val_i + n * avgdel * avgdel) / nm1;
- if (stddev <= 0)
- stddev = 0.01; /* must have been rounding error or zero; prevent division by zero */
- /* now calculate load based on how far out we are from
- std dev; or if we are below average, simply assume load zero */
- if (load->runavg_delay < avgdel)
- load->load = 0.0;
- else
- load->load = (load->runavg_delay - avgdel) / stddev;
- }
}
+
/* end of load.c */
projects / oweals / gnunet.git / blobdiff