ipcpd: Add flow overshoot protection to mb-ecntestingbe

The ECN marks were the only source of congestion information, and
going into congestion collapse (dropping a lot of ECN packets and
causing loss of signal) was unrecoverable.

The sender's slow-start ramp clock now tracks a measured RTT to avoid
overshooting into congestion collapse on the previously fixed (14ms)
doubling on long-delay (e.g. 100ms) links.

The flow allocator now carries a periodic heartbeat/ack to keep RTT
estimates up-to-date. The heartbeat also serves as a congestion
collapse detector: consecutive heartbeat losses will go into loss
recovery, halving the window and pausing Additive Increase until the
path is clear. The DT component now has a max_rtt config parameter that
serves as a hint for the layer RTT to optimize slow-start for
low-latency networks.

These two mechanisms follow TCP, however only during slow start up to
the first ECN signal and to recover from a total collapse until the
ECN signal returns. MB-ECN is still fully RTT-independent in the AI/PD
region. A shorter RTT path will just reach its equal fair share faster
than a longer RTT path.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 7 insertions, 7 deletions

diff --git a/src/ipcpd/unicast/ca/tests/ca_test.c b/src/ipcpd/unicast/ca/tests/ca_test.c
index 4c44d29e..1b86eab8 100644
--- a/src/ipcpd/unicast/ca/tests/ca_test.c
+++ b/src/ipcpd/unicast/ca/tests/ca_test.c
@@ -44,7 +44,7 @@ static int test_ca_init_fini(enum pol_cong_avoid pol,
 {
         TEST_START("(%s)", name);
 
-        if (ca_init(pol) < 0) {
+        if (ca_init(pol, 100) < 0) {
                 printf("Failed to init ca for %s.\n", name);
                 goto fail;
         }
@@ -74,7 +74,7 @@ static int test_ca_init_invalid(void)
 {
         TEST_START();
 
-        if (ca_init(CA_INVALID) == 0) {
+        if (ca_init(CA_INVALID, 100) == 0) {
                 printf("Init accepted an invalid policy.\n");
                 ca_fini();
                 goto fail;
@@ -96,7 +96,7 @@ static int test_ca_ctx_share(enum pol_cong_avoid pol,
 
         TEST_START("(%s)", name);
 
-        if (ca_init(pol) < 0) {
+        if (ca_init(pol, 100) < 0) {
                 printf("Failed to init ca for %s.\n", name);
                 goto fail;
         }
@@ -162,7 +162,7 @@ static int test_ca_ctx_distinct(void)
 
         TEST_START();
 
-        if (ca_init(CA_NONE) < 0) {
+        if (ca_init(CA_NONE, 100) < 0) {
                 printf("Failed to init ca.\n");
                 goto fail;
         }
@@ -226,7 +226,7 @@ static int test_ca_ctx_refcount(void)
 
         TEST_START();
 
-        if (ca_init(CA_NONE) < 0) {
+        if (ca_init(CA_NONE, 100) < 0) {
                 printf("Failed to init ca.\n");
                 goto fail;
         }
@@ -283,7 +283,7 @@ static int test_ca_ctx_recreate(void)
 
         TEST_START();
 
-        if (ca_init(CA_NONE) < 0) {
+        if (ca_init(CA_NONE, 100) < 0) {
                 printf("Failed to init ca.\n");
                 goto fail;
         }
@@ -340,7 +340,7 @@ static int test_ca_fini_drains(void)
 
         TEST_START();
 
-        if (ca_init(CA_NONE) < 0) {
+        if (ca_init(CA_NONE, 100) < 0) {
                 printf("Failed to init ca.\n");
                 goto fail;
         }