red: harddrop support and cleanups

Add harddrop support (kernel support added a long time ago), and various
cleanups.

min BYTES, max BYTES are now optional and follow Sally Floyd's
recommendations.

By the way, our default 2% probability is a bit low, Sally recommends 10%.
Not a big deal if upcoming adaptative algo is deployed.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

diff --git a/tc/q_red.c b/tc/q_red.c
index 6e58d7a788e32845652357b4cf89d5d9d1ae4be6..18020d7d4b8c3acbb33d9cbed9f0f62476b9a573 100644 (file)
--- a/tc/q_red.c
+++ b/tc/q_red.c
@@ -27,8 +27,8 @@
 
 static void explain(void)
 {
-       fprintf(stderr, "Usage: ... red limit BYTES min BYTES max BYTES avpkt BYTES burst PACKETS\n");
-       fprintf(stderr, "               probability PROBABILITY bandwidth KBPS [ ecn ]\n");
+       fprintf(stderr, "Usage: ... red limit BYTES [min BYTES] [max BYTES] avpkt BYTES [burst PACKETS]\n");
+       fprintf(stderr, "               [probability PROBABILITY] bandwidth KBPS [ecn] [harddrop]\n");
 }
 
 static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nlmsghdr *n)
@@ -38,7 +38,6 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
        unsigned avpkt = 0;
        double probability = 0.02;
        unsigned rate = 0;
-       int ecn_ok = 0;
        int wlog;
        __u8 sbuf[256];
        struct rtattr *tail;
@@ -89,7 +88,9 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
                                return -1;
                        }
                } else if (strcmp(*argv, "ecn") == 0) {
-                       ecn_ok = 1;
+                       opt.flags |= TC_RED_ECN;
+               } else if (strcmp(*argv, "harddrop") == 0) {
+                       opt.flags |= TC_RED_HARDDROP;
                } else if (strcmp(*argv, "help") == 0) {
                        explain();
                        return -1;
@@ -104,14 +105,20 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
        if (rate == 0)
                get_rate(&rate, "10Mbit");
 
-       if (!opt.qth_min || !opt.qth_max || !opt.limit || !avpkt) {
-               fprintf(stderr, "RED: Required parameter (min, max, limit, avpkt) is missing\n");
+       if (!opt.limit || !avpkt) {
+               fprintf(stderr, "RED: Required parameter (limit, avpkt) is missing\n");
                return -1;
        }
-       if (!burst) {
+       /* Compute default min/max thresholds based on
+        * Sally Floyd's recommendations:
+        * http://www.icir.org/floyd/REDparameters.txt
+        */
+       if (!opt.qth_max)
+               opt.qth_max = opt.qth_min ? opt.qth_min * 3 : opt.limit / 4;
+       if (!opt.qth_min)
+               opt.qth_min = opt.qth_max / 3;
+       if (!burst)
                burst = (2 * opt.qth_min + opt.qth_max) / (3 * avpkt);
-               fprintf(stderr, "RED: set burst to %u\n", burst);
-       }
        if ((wlog = tc_red_eval_ewma(opt.qth_min, burst, avpkt)) < 0) {
                fprintf(stderr, "RED: failed to calculate EWMA constant.\n");
                return -1;
@@ -129,14 +136,6 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
                return -1;
        }
        opt.Scell_log = wlog;
-       if (ecn_ok) {
-#ifdef TC_RED_ECN
-               opt.flags |= TC_RED_ECN;
-#else
-               fprintf(stderr, "RED: ECN support is missing in this binary.\n");
-               return -1;
-#endif
-       }
 
        tail = NLMSG_TAIL(n);
        addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
@@ -148,7 +147,7 @@ static int red_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nl
 
 static int red_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
 {
-       struct rtattr *tb[TCA_RED_STAB+1];
+       struct rtattr *tb[TCA_RED_MAX + 1];
        struct tc_red_qopt *qopt;
        SPRINT_BUF(b1);
        SPRINT_BUF(b2);
@@ -157,7 +156,7 @@ static int red_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
        if (opt == NULL)
                return 0;
 
-       parse_rtattr_nested(tb, TCA_RED_STAB, opt);
+       parse_rtattr_nested(tb, TCA_RED_MAX, opt);
 
        if (tb[TCA_RED_PARMS] == NULL)
                return -1;
@@ -168,10 +167,10 @@ static int red_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
                sprint_size(qopt->limit, b1),
                sprint_size(qopt->qth_min, b2),
                sprint_size(qopt->qth_max, b3));
-#ifdef TC_RED_ECN
        if (qopt->flags & TC_RED_ECN)
                fprintf(f, "ecn ");
-#endif
+       if (qopt->flags & TC_RED_HARDDROP)
+               fprintf(f, "harddrop ");
        if (show_details) {
                fprintf(f, "ewma %u Plog %u Scell_log %u",
                        qopt->Wlog, qopt->Plog, qopt->Scell_log);