llc: Add CoDel AQM implementation
This commit adds an implementation of the CoDel algorithm based on
the reference pseudocode presented in
http://queue.acm.org/appendices/codel.html. Instead of abstracting
the queue itself, the implementation provides a time stamp based
automaton which is invoked after a package has been dequeued.
Note that the modifications of the algorithm shown in
https://tools.ietf.org/html/draft-ietf-aqm-codel-01 are not yet
applied.
Sponsored-by: On-Waves ehf
diff --git a/tests/codel/codel_test.c b/tests/codel/codel_test.c
new file mode 100644
index 0000000..91bad13
--- /dev/null
+++ b/tests/codel/codel_test.c
@@ -0,0 +1,147 @@
+/* Test routines for the CoDel implementation
+ *
+ * (C) 2015 by sysmocom s.f.m.c. GmbH
+ * Author: Jacob Erlbeck <jerlbeck@sysmocom.de>
+ */
+
+#undef _GNU_SOURCE
+#define _GNU_SOURCE
+
+#if 0
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/prim.h>
+#endif
+#include <osmocom/core/application.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+
+#include "gprs_codel.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+static int do_codel_control(struct gprs_codel *state, const struct timeval *recv,
+ struct timeval *now, const struct timeval *delta_now, int count)
+{
+ int drop;
+
+ drop = gprs_codel_control(state, recv, now, -1);
+ if (drop) {
+ printf("Dropping packet %d, "
+ "recv = %d.%03d, now = %d.%03d, "
+ "codel.count = %d\n",
+ count,
+ (int)recv->tv_sec, (int)recv->tv_usec/1000,
+ (int)now->tv_sec, (int)now->tv_usec/1000,
+ state->count);
+ } else {
+ timeradd(now, delta_now, now);
+ }
+
+ return drop == 0 ? 0 : 1;
+}
+
+static void test_codel(void)
+{
+ struct gprs_codel codel;
+ struct timeval now;
+ struct timeval recv;
+ const struct timeval delta_now = {0, 10000};
+ const struct timeval init_delta_recv = {0, 5000};
+ struct timeval delta_recv;
+ unsigned count;
+ unsigned sum = 0;
+ unsigned dropped = 0;
+ int drop;
+
+ printf("----- %s START\n", __func__);
+ gprs_codel_init(&codel);
+ gprs_codel_set_interval(&codel, 100);
+
+ timerclear(&now);
+ timerclear(&recv);
+ delta_recv = init_delta_recv;
+
+ for (count = 0; count < 20; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ printf("Dropped %d packets\n", dropped);
+ OSMO_ASSERT(dropped == 0);
+ OSMO_ASSERT(!codel.dropping);
+
+ for (count = 0; count < 20; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ OSMO_ASSERT(dropped == 2);
+ OSMO_ASSERT(codel.dropping);
+
+ /* slow down recv rate */
+ delta_recv.tv_usec = delta_now.tv_usec;
+
+ for (count = 0; count < 75; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ OSMO_ASSERT(dropped == 20);
+ OSMO_ASSERT(codel.dropping);
+
+ for (count = 0; count < 50; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ OSMO_ASSERT(dropped == 20);
+ OSMO_ASSERT(!codel.dropping);
+ OSMO_ASSERT(codel.count >= 20);
+
+ /* go back to old data rate */
+ delta_recv = init_delta_recv;
+
+ for (count = 0; count < 20; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ OSMO_ASSERT(dropped == 20);
+ OSMO_ASSERT(!codel.dropping);
+
+ for (count = 0; count < 20; count++, sum++) {
+ drop = do_codel_control(&codel, &recv, &now, &delta_now, sum);
+ timeradd(&recv, &delta_recv, &recv);
+ dropped += drop;
+ }
+
+ OSMO_ASSERT(dropped == 22);
+ OSMO_ASSERT(codel.count >= 2);
+
+ printf("Dropped %d packets\n", dropped);
+
+ printf("----- %s END\n", __func__);
+}
+
+static struct log_info info = {};
+
+int main(int argc, char **argv)
+{
+ osmo_init_logging(&info);
+ log_set_use_color(osmo_stderr_target, 0);
+ log_set_print_filename(osmo_stderr_target, 0);
+ log_set_log_level(osmo_stderr_target, LOGL_INFO);
+
+ printf("===== CoDel test START\n");
+ test_codel();
+ printf("===== CoDel test END\n\n");
+
+ exit(EXIT_SUCCESS);
+}