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authorDimitri Staessens <dimitri@ouroboros.rocks>2021-06-19 13:51:28 +0200
committerSander Vrijders <sander@ouroboros.rocks>2021-06-21 08:45:42 +0200
commit95ca0c60dbe88d5cfff71234dc1483406241bf26 (patch)
tree797c6c6bc91deb2522ea09417f517238cc44930d
parent1a13d42a0792a4a12a40c813072355502e87c42f (diff)
downloadouroboros-95ca0c60dbe88d5cfff71234dc1483406241bf26.zip
ouroboros-95ca0c60dbe88d5cfff71234dc1483406241bf26.tar.gz
ipcpd: Fix congestion window scaling
This fixes scaling of the congestion window, which was a buggy mess. Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks> Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
-rw-r--r--src/ipcpd/unicast/pol/ca-mb-ecn.c59
1 files changed, 41 insertions, 18 deletions
diff --git a/src/ipcpd/unicast/pol/ca-mb-ecn.c b/src/ipcpd/unicast/pol/ca-mb-ecn.c
index 9f07fc7..7f570a9 100644
--- a/src/ipcpd/unicast/pol/ca-mb-ecn.c
+++ b/src/ipcpd/unicast/pol/ca-mb-ecn.c
@@ -33,6 +33,7 @@
#include "ca-mb-ecn.h"
+#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
@@ -42,12 +43,12 @@
#define CA_WND (1 << CA_SHFT) /* 32 pkts receiver wnd */
#define CA_UPD (1 << (CA_SHFT - 3)) /* Update snd every 8 pkt */
#define CA_SLOT 24 /* Initial slot = 16 ms */
-#define CA_INC 1 << 16 /* ~4MiB/s^2 additive inc */
-#define CA_IWL 1 << 16 /* Initial limit ~4MiB/s */
+#define CA_INC 1UL << 16 /* ~4MiB/s^2 additive inc */
+#define CA_IWL 1UL << 16 /* Initial limit ~4MiB/s */
#define CA_MINPS 8 /* Mimimum pkts / slot */
#define CA_MAXPS 64 /* Maximum pkts / slot */
#define ECN_Q_SHFT 4
-#define ts_to_ns(ts) (ts.tv_sec * BILLION + ts.tv_nsec)
+#define ts_to_ns(ts) ((size_t) ts.tv_sec * BILLION + ts.tv_nsec)
struct mb_ecn_ctx {
uint16_t rx_ece; /* Level of congestion (upstream) */
@@ -101,6 +102,8 @@ void mb_ecn_ctx_destroy(void * ctx)
free(ctx);
}
+#define _slot_after(new, old) ((int64_t) (old - new) < 0)
+
ca_wnd_t mb_ecn_ctx_update_snd(void * _ctx,
size_t len)
{
@@ -120,7 +123,9 @@ ca_wnd_t mb_ecn_ctx_update_snd(void * _ctx,
if (ctx->tx_ctr > CA_WND)
ctx->tx_ece = 0;
- if (slot > ctx->tx_slot) {
+ if (_slot_after(slot, ctx->tx_slot)) {
+ bool carry = false; /* may carry over if window increases */
+
ctx->tx_slot = slot;
if (!ctx->tx_cav) { /* Slow start */
@@ -136,21 +141,39 @@ ca_wnd_t mb_ecn_ctx_update_snd(void * _ctx,
/* Window scaling */
if (ctx->tx_wpc < CA_MINPS) {
- ++ctx->tx_mul;
- ctx->tx_slot >>= 1;
- ctx->tx_wbl <<= 1;
- ctx->tx_inc <<= 1;
+ size_t fact = 0; /* factor to scale the window up */
+ size_t pkts = ctx->tx_wpc;
+ while (pkts < CA_MINPS) {
+ pkts <<= 1;
+ fact++;
+ }
+ ctx->tx_mul += fact;
+ ctx->tx_slot >>= fact;
+ if ((ctx->tx_slot & ((1 << fact) - 1)) == 0) {
+ carry = true;
+ ctx->tx_slot += 1;
+ }
+ ctx->tx_wbl <<= fact;
+ ctx->tx_inc <<= fact;
+ } else if (ctx->tx_wpc > CA_MAXPS) {
+ size_t fact = 0; /* factor to scale the window down */
+ size_t pkts = ctx->tx_wpc;
+ while (pkts > CA_MAXPS) {
+ pkts >>= 1;
+ fact++;
+ }
+ ctx->tx_mul -= fact;
+ ctx->tx_slot <<= fact;
+ ctx->tx_wbl >>= fact;
+ ctx->tx_inc >>= fact;
+ } else {
+ ctx->tx_slot = slot;
}
- if (ctx->tx_wpc > CA_MAXPS) {
- --ctx->tx_mul; /* Underflows at ~CA_MAXPS billion pps */
- ctx->tx_slot <<= 1;
- ctx->tx_wbl >>= 1;
- ctx->tx_inc >>= 1;
+ if (!carry) {
+ ctx->tx_wbc = 0;
+ ctx->tx_wpc = 0;
}
-
- ctx->tx_wbc = 0;
- ctx->tx_wpc = 0;
}
if (ctx->tx_wbc > ctx->tx_wbl)
@@ -258,14 +281,14 @@ ssize_t mb_ecn_print_stats(void * _ctx,
"Upstream packet counter: %20zu\n"
"Downstream congestion level: %20u\n"
"Downstream packet counter: %20zu\n"
- "Congestion window size (ns): %20zu\n"
+ "Congestion window size (ns): %20" PRIu64 "\n"
"Packets in this window: %20zu\n"
"Bytes in this window: %20zu\n"
"Max bytes in this window: %20zu\n"
"Current congestion regime: %20s\n",
"Multi-bit ECN",
ctx->rx_ece, ctx->rx_ctr,
- ctx->tx_ece, ctx->tx_ctr, (size_t) (1 << ctx->tx_mul),
+ ctx->tx_ece, ctx->tx_ctr, (size_t) (1UL << ctx->tx_mul),
ctx->tx_wpc, ctx->tx_wbc, ctx->tx_wbl,
regime);