Add RLC stats: avg time to tx for an RLC SDU

cmake_targets/CMakeLists.txt

@@ -1216,6 +1216,7 @@ add_library(UTIL
   ${OPENAIR_DIR}/common/utils/system.c
   ${OPENAIR_DIR}/common/utils/backtrace.c
   ${OPENAIR_DIR}/common/utils/time_meas.c
+  ${OPENAIR_DIR}/common/utils/time_stat.c
 )
 
 set(SECU_OSA_SRC

common/utils/time_stat.c

@@ -0,0 +1,125 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#include "time_stat.h"
+
+#include <time.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "common/utils/LOG/log.h"
+
+time_average_t *time_average_new(int duration, int initial_size)
+{
+  time_average_t *ret;
+
+  /* let's only accept power of two initial_size */
+  if (initial_size & (initial_size - 1)) {
+    LOG_E(UTIL, "time_average_new: illegal initial_size %d, use power of two\n", initial_size);
+    exit(1);
+  }
+
+  ret = calloc(1, sizeof(time_average_t));
+  if (ret == NULL) {
+    LOG_E(UTIL, "out of memory\n");
+    exit(1);
+  }
+
+  ret->duration = duration;
+  ret->r.head = initial_size - 1;
+  ret->r.maxsize = initial_size;
+  ret->r.buffer = calloc(initial_size, sizeof(time_value_t));
+  if (ret->r.buffer == NULL) {
+    LOG_E(UTIL, "out of memory\n");
+    exit(1);
+  }
+
+  return ret;
+}
+
+void time_average_free(time_average_t *t)
+{
+  free(t->r.buffer);
+  free(t);
+}
+
+static void remove_old(time_average_t *t, uint64_t time)
+{
+  /* remove old events */
+  while (t->r.size && t->r.buffer[t->r.tail].time < time - t->duration) {
+    t->accumulated_value -= t->r.buffer[t->r.tail].value;
+    t->r.size--;
+    t->r.tail++;
+    t->r.tail %= t->r.maxsize;
+  }
+}
+
+void time_average_add(time_average_t *t, uint64_t time, uint64_t value)
+{
+  remove_old(t, time);
+
+  if (t->r.size == t->r.maxsize) {
+    t->r.maxsize *= 2;
+    t->r.buffer = realloc(t->r.buffer, t->r.maxsize * sizeof(time_value_t));
+    if (t->r.buffer == NULL) {
+      LOG_E(UTIL, "out of memory\n");
+      exit(1);
+    }
+    if (t->r.head < t->r.tail) {
+      memcpy(&t->r.buffer[t->r.size], &t->r.buffer[0], (t->r.head + 1) * sizeof(time_value_t));
+      t->r.head += t->r.size;
+    }
+  }
+
+  t->r.head++;
+  t->r.head %= t->r.maxsize;
+  t->r.buffer[t->r.head].time = time;
+  t->r.buffer[t->r.head].value = value;
+
+  t->r.size++;
+
+  t->accumulated_value += value;
+}
+
+double time_average_get_average(time_average_t *t, uint64_t time)
+{
+  remove_old(t, time);
+
+  return (double)t->accumulated_value / t->r.size;
+}
+
+uint64_t time_average_now(void)
+{
+  struct timespec t;
+  uint64_t ret;
+
+  if (clock_gettime(CLOCK_REALTIME, &t)) {
+    LOG_E(UTIL, "clock_gettime failed\n");
+    exit(1);
+  }
+
+  ret = (uint64_t)t.tv_sec * (uint64_t)1000000 + t.tv_nsec / 1000;
+  /* round up if necessary */
+  if (t.tv_nsec % 1000 >= 500)
+    ret++;
+
+  return ret;
+}

common/utils/time_stat.h

@@ -0,0 +1,63 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#ifndef _COMMON_UTIL_TIME_STAT_H_
+#define _COMMON_UTIL_TIME_STAT_H_
+
+#include <stdint.h>
+
+typedef struct {
+  uint64_t time;     /* unit: microsecond */
+  uint64_t value;    /* unit: microsecond */
+} time_value_t;
+
+typedef struct {
+  int head;
+  int tail;
+  time_value_t *buffer;
+  int maxsize;
+  int size;
+} time_ring_t;
+
+typedef struct {
+  int duration;     /* unit: microsecond */
+  time_ring_t r;
+  uint64_t accumulated_value;
+} time_average_t;
+
+/* 'duration' is in unit microsecond */
+time_average_t *time_average_new(int duration, int initial_size);
+void time_average_free(time_average_t *t);
+
+/* add a value tagged with time 'time' unit microsecond (it also modifies 't',
+ * removing all data with time < 'time' - t->duration)
+ */
+void time_average_add(time_average_t *t, uint64_t time, uint64_t value);
+
+/* get the average for time 'time' (it also modifies 't', removing all
+ * data with time < 'time' - t->duration)
+ */
+double time_average_get_average(time_average_t *t, uint64_t time);
+
+/* unit microsecond */
+uint64_t time_average_now(void);
+
+#endif /* _COMMON_UTIL_TIME_STAT_H_ */

openair2/LAYER2/nr_rlc/nr_rlc_entity.c

@@ -29,12 +29,16 @@
 
 #include "LOG/log.h"
 
+#include "common/utils/time_stat.h"
+
 static void nr_rlc_entity_get_stats(
     nr_rlc_entity_t *entity,
     nr_rlc_statistics_t *out)
 {
 // printf("Stats from the RLC entity asked\n");
   *out = entity->stats;
+  out->txsdu_avg_time_to_tx = time_average_get_average(entity->txsdu_avg_time_to_tx,
+                                  time_average_now());
 }
 
 nr_rlc_entity_t *new_nr_rlc_entity_am(
@@ -105,6 +109,11 @@ nr_rlc_entity_t *new_nr_rlc_entity_am(
 
   ret->common.stats.mode = 0;  /* 0 for AM */
 
+  /* let's take average over the last 100 milliseconds
+   * initial_size of 1024 is arbitrary
+   */
+  ret->common.txsdu_avg_time_to_tx = time_average_new(100 * 1000, 1024);
+
   return (nr_rlc_entity_t *)ret;
 }
 
@@ -155,6 +164,11 @@ nr_rlc_entity_t *new_nr_rlc_entity_um(
 
   ret->common.stats.mode = 1;  /* 1 for UM */
 
+  /* let's take average over the last 100 milliseconds
+   * initial_size of 1024 is arbitrary
+   */
+  ret->common.txsdu_avg_time_to_tx = time_average_new(100 * 1000, 1024);
+
   return (nr_rlc_entity_t *)ret;
 }
 
@@ -190,5 +204,10 @@ nr_rlc_entity_t *new_nr_rlc_entity_tm(
 
   ret->common.stats.mode = 2;  /* 2 for TM */
 
+  /* let's take average over the last 100 milliseconds
+   * initial_size of 1024 is arbitrary
+   */
+  ret->common.txsdu_avg_time_to_tx = time_average_new(100 * 1000, 1024);
+
   return (nr_rlc_entity_t *)ret;
 }

openair2/LAYER2/nr_rlc/nr_rlc_entity.h

@@ -24,6 +24,8 @@
 
 #include <stdint.h>
 
+#include "common/utils/time_stat.h"
+
 #define NR_SDU_MAX 16000   /* max NR PDCP SDU size is 9000, let's take more */
 
 typedef struct {
@@ -77,6 +79,16 @@ typedef struct {
   uint32_t rxsdu_bytes;        /* number of bytes of SDUs received */
   uint32_t rxsdu_dd_pkts;      /* number of dropped or discarded SDUs */
   uint32_t rxsdu_dd_bytes;     /* number of bytes of SDUs dropped or discarded */
+
+  /* Average time for an SDU to be passed to MAC.
+   * Actually measures the time it takes for any part of an SDU to be
+   * passed to MAC for the first time, that is: the first TX of (part of) the
+   * SDU.
+   * Since the MAC schedules in advance, it does not measure the time of
+   * transmission over the air, just the time to reach the MAC layer.
+   */
+  double txsdu_avg_time_to_tx;
+
 } nr_rlc_statistics_t;
 
 typedef struct {
@@ -124,6 +136,7 @@ typedef struct nr_rlc_entity_t {
   nr_rlc_entity_buffer_status_t bstatus;
 
   nr_rlc_statistics_t stats;
+  time_average_t *txsdu_avg_time_to_tx;
 } nr_rlc_entity_t;
 
 nr_rlc_entity_t *new_nr_rlc_entity_am(

openair2/LAYER2/nr_rlc/nr_rlc_entity_am.c

@@ -27,6 +27,7 @@
 #include "nr_rlc_pdu.h"
 
 #include "LOG/log.h"
+#include "common/utils/time_stat.h"
 
 /* for a given SDU/SDU segment, computes the corresponding PDU header size */
 static int compute_pdu_header_size(nr_rlc_entity_am_t *entity,
@@ -1620,6 +1621,14 @@ static int generate_tx_pdu(nr_rlc_entity_am_t *entity, char *buffer, int size)
   entity->common.stats.txpdu_pkts++;
   entity->common.stats.txpdu_bytes += ret_size;
 
+  if (sdu->sdu->time_of_arrival) {
+    uint64_t time_now = time_average_now();
+    uint64_t waited_time = time_now - sdu->sdu->time_of_arrival;
+    /* set time_of_arrival to 0 so as to update stats only once */
+    sdu->sdu->time_of_arrival = 0;
+    time_average_add(entity->common.txsdu_avg_time_to_tx, time_now, waited_time);
+  }
+
   return ret_size;
 //  return serialize_sdu(entity, sdu, buffer, size, p);
 }
@@ -1708,6 +1717,8 @@ void nr_rlc_entity_am_recv_sdu(nr_rlc_entity_t *_entity,
   /* update buffer status */
   entity->common.bstatus.tx_size += compute_pdu_header_size(entity, sdu)
                                     + sdu->size;
+
+  sdu->sdu->time_of_arrival = time_average_now();
 }
 
 /*************************************************************************/
@@ -1949,6 +1960,7 @@ void nr_rlc_entity_am_delete(nr_rlc_entity_t *_entity)
 {
   nr_rlc_entity_am_t *entity = (nr_rlc_entity_am_t *)_entity;
   clear_entity(entity);
+  time_average_free(entity->common.txsdu_avg_time_to_tx);
   free(entity);
 }
 

openair2/LAYER2/nr_rlc/nr_rlc_entity_tm.c

@@ -25,6 +25,7 @@
 #include <string.h>
 
 #include "nr_rlc_pdu.h"
+#include "common/utils/time_stat.h"
 
 #include "LOG/log.h"
 
@@ -78,6 +79,13 @@ static int generate_tx_pdu(nr_rlc_entity_tm_t *entity, char *buffer, int size)
   entity->common.stats.txpdu_pkts++;
   entity->common.stats.txpdu_bytes += size;
 
+  if (sdu->sdu->time_of_arrival) {
+    uint64_t time_now = time_average_now();
+    uint64_t waited_time = time_now - sdu->sdu->time_of_arrival;
+    /* set time_of_arrival to 0 so as to update stats only once */
+    sdu->sdu->time_of_arrival = 0;
+    time_average_add(entity->common.txsdu_avg_time_to_tx, time_now, waited_time);
+  }
 
   /* update buffer status */
   entity->common.bstatus.tx_size -= sdu->size;
@@ -189,6 +197,7 @@ void nr_rlc_entity_tm_delete(nr_rlc_entity_t *_entity)
 {
   nr_rlc_entity_tm_t *entity = (nr_rlc_entity_tm_t *)_entity;
   clear_entity(entity);
+  time_average_free(entity->common.txsdu_avg_time_to_tx);
   free(entity);
 }
 

openair2/LAYER2/nr_rlc/nr_rlc_entity_um.c

@@ -27,6 +27,7 @@
 #include "nr_rlc_pdu.h"
 
 #include "LOG/log.h"
+#include "common/utils/time_stat.h"
 
 /* for a given SDU/SDU segment, computes the corresponding PDU header size */
 static int compute_pdu_header_size(nr_rlc_entity_um_t *entity,
@@ -516,12 +517,19 @@ static int generate_tx_pdu(nr_rlc_entity_um_t *entity, char *buffer, int size)
   ret = serialize_sdu(entity, sdu, buffer, size);
 
   entity->tx_size -= sdu->size;
-  nr_rlc_free_sdu_segment(sdu);
 
   entity->common.stats.txpdu_pkts++;
   entity->common.stats.txpdu_bytes += size;
 
+  if (sdu->sdu->time_of_arrival) {
+    uint64_t time_now = time_average_now();
+    uint64_t waited_time = time_now - sdu->sdu->time_of_arrival;
+    /* set time_of_arrival to 0 so as to update stats only once */
+    sdu->sdu->time_of_arrival = 0;
+    time_average_add(entity->common.txsdu_avg_time_to_tx, time_now, waited_time);
+  }
 
+  nr_rlc_free_sdu_segment(sdu);
 
   return ret;
 }
@@ -736,6 +744,7 @@ void nr_rlc_entity_um_delete(nr_rlc_entity_t *_entity)
 {
   nr_rlc_entity_um_t *entity = (nr_rlc_entity_um_t *)_entity;
   clear_entity(entity);
+  time_average_free(entity->common.txsdu_avg_time_to_tx);
   free(entity);
 }
 

openair2/LAYER2/nr_rlc/nr_rlc_sdu.h

@@ -22,6 +22,8 @@
 #ifndef _NR_RLC_SDU_H_
 #define _NR_RLC_SDU_H_
 
+#include <stdint.h>
+
 typedef struct nr_rlc_sdu_t {
   int sn;
   int upper_layer_id;
@@ -34,6 +36,12 @@ typedef struct nr_rlc_sdu_t {
                        * when it equals ref_count we can free the SDU
                        * completely
                        */
+
+  /* for statistics, will be set to 0 after SDU (or first part of it) has
+   * been serialized for MAC for the first time so that only the first
+   * transmission is used for statistics
+   */
+  uint64_t time_of_arrival;  /* unit microsecond */
 } nr_rlc_sdu_t;
 
 typedef struct nr_rlc_sdu_segment_t {

openair2/LAYER2/nr_rlc/tests/Makefile

@@ -1,8 +1,8 @@
 CC=gcc
-CFLAGS=-Wall -g --coverage -I.
+CFLAGS=-Wall -g --coverage -I. -I../../../..
 
 LIB=nr_rlc_entity.o nr_rlc_entity_am.o nr_rlc_entity_um.o nr_rlc_entity_tm.o \
-    nr_rlc_pdu.o nr_rlc_sdu.o
+    nr_rlc_pdu.o nr_rlc_sdu.o time_stat.o
 
 tests:
 	@./run_tests.sh

openair2/LAYER2/nr_rlc/tests/time_stat.c

@@ -0,0 +1,25 @@
+#include "../../../../common/utils/time_stat.h"
+
+time_average_t *time_average_new(int duration, int initial_size)
+{
+  return (void *)0;
+}
+
+void time_average_free(time_average_t *t)
+{
+}
+
+void time_average_add(time_average_t *t, uint64_t time, uint64_t value)
+{
+}
+
+double time_average_get_average(time_average_t *t, uint64_t time)
+{
+  return 0;
+}
+
+uint64_t time_average_now(void)
+{
+  return 0;
+}
+