ipcpd: Use capacity queue estimation for mb-ecn

The mb-ecn algorithm was using rbuff queue depths in packets to mark,
but sockets in the poa component report capacity in bytes. The tx
rings are now adaptive to block on queuing delay instead of when full
to prevent buffer bloat, controllable via fccntl (FLOWSTXQDLY and
FLOWGTXQDLY).

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

2 files changed, 14 insertions, 29 deletions

diff --git a/src/lib/poa/poa.c b/src/lib/poa/poa.c
index 3ad17c4f..b40d9fea 100644
--- a/src/lib/poa/poa.c
+++ b/src/lib/poa/poa.c
@@ -1678,9 +1678,9 @@ size_t poa_flow_mean_len(const struct poa_flow * pf)
         return LOAD_RELAXED(&pf->poa->avg_len);
 }
 
-int poa_flow_qid(const struct poa_flow * pf)
+struct cap_est * poa_flow_cap_est(struct poa_flow * pf)
 {
-        return pf->poa->qid;
+        return &pf->poa->cap;
 }
 
 void poa_flow_ready(struct poa_flow * pf)
@@ -1830,7 +1830,6 @@ static struct poa * poa_create(enum poa_type          type,
         poa->ops    = ops;
         poa->mpl    = ops->mpl;
         poa->n_eids = n_eids;
-        poa->qid    = -1;
 
         return poa;
 
@@ -2213,30 +2212,15 @@ void poa_fini(void)
         pthread_mutex_destroy(&poas.mtx);
 }
 
-/*
- * Lowest queue id no attached PoA holds; detaching frees it by
- * leaving the list. Caller holds poas.lock.
- */
-static int poa_qid_alloc(void)
+static size_t poa_count(void)
 {
         struct list_head * p;
-        bool               used[POA_MAX_POAS];
-        int                i;
-
-        memset(used, 0, sizeof(used));
-
-        list_for_each(p, &poas.list) {
-                struct poa * poa = list_entry(p, struct poa, next);
-
-                if (poa->qid >= 0 && poa->qid < POA_MAX_POAS)
-                        used[poa->qid] = true;
-        }
+        size_t             n = 0;
 
-        for (i = 0; i < POA_MAX_POAS; i++)
-                if (!used[i])
-                        return i;
+        list_for_each(p, &poas.list)
+                n++;
 
-        return -1;
+        return n;
 }
 
 static int poa_add(const struct poa_spec * spec,
@@ -2275,8 +2259,7 @@ static int poa_add(const struct poa_spec * spec,
 
         pthread_rwlock_wrlock(&poas.lock);
 
-        poa->qid = poa_qid_alloc();
-        if (poa->qid < 0) {
+        if (poa_count() >= POA_MAX_POAS) {
                 pthread_rwlock_unlock(&poas.lock);
                 goto fail_start;
         }
diff --git a/src/lib/poa/poa.h b/src/lib/poa/poa.h
index 014986a3..9edb0335 100644
--- a/src/lib/poa/poa.h
+++ b/src/lib/poa/poa.h
@@ -34,6 +34,8 @@
 #include <ouroboros/time.h>
 #include <ouroboros/utils.h>
 
+#include "../cap.h"
+
 #include <errno.h>
 #include <limits.h>
 #include <poll.h>
@@ -191,9 +193,6 @@ struct poa {
 
         time_t                 mpl;
 
-        /* Identifies the transmit queue the flows on this PoA share. */
-        int                    qid;
-
         /* Mean sent packet size (bytes), EWMA over the send path. */
         size_t                 avg_len;
         /* Cost of one packet in the queue, in the transport's terms. */
@@ -204,6 +203,9 @@ struct poa {
         size_t                 q_cache;
         uint64_t               q_time;
 
+        /* Capacity estimator of the queue the flows on this PoA share. */
+        struct cap_est         cap;
+
         /* Queued management frames, capped; poas.mgmt_mtx guards. */
         size_t                 n_mgmt;
 
@@ -245,7 +247,7 @@ size_t            poa_flow_qlen(const struct poa_flow * pf);
 
 size_t            poa_flow_qpkts(const struct poa_flow * pf);
 
-int               poa_flow_qid(const struct poa_flow * pf);
+struct cap_est *  poa_flow_cap_est(struct poa_flow * pf);
 
 size_t            poa_flow_mean_len(const struct poa_flow * pf);