This enhances the network simulation scheduler to do simple random loss.
The loss parameter is a simple 32 bit value such that 0 means no loss, and
0xffffffff is always drop. I have a new version of the tc command which takes
care of conversion from percent to this value.
Same patch for 2.4 and 2.6
Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxx>
diff -Nru a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
--- a/include/linux/pkt_sched.h 2004-06-17 15:26:51 -07:00
+++ b/include/linux/pkt_sched.h 2004-06-17 15:26:51 -07:00
@@ -437,5 +437,6 @@
{
__u32 latency;
__u32 limit;
-};
+ __u32 loss;
+};
#endif
diff -Nru a/net/sched/sch_delay.c b/net/sched/sch_delay.c
--- a/net/sched/sch_delay.c 2004-06-17 15:26:51 -07:00
+++ b/net/sched/sch_delay.c 2004-06-17 15:26:51 -07:00
@@ -40,6 +40,7 @@
struct dly_sched_data {
u32 latency;
u32 limit;
+ u32 loss;
struct timer_list timer;
struct Qdisc *qdisc;
};
@@ -58,6 +59,12 @@
struct dly_skb_cb *cb = (struct dly_skb_cb *)skb->cb;
int ret;
+ /* Random packet drop 0 => none, ~0 => all */
+ if (q->loss >= net_random()) {
+ sch->stats.drops++;
+ return 0; /* lie about loss so TCP doesn't know */
+ }
+
PSCHED_GET_TIME(cb->queuetime);
/* Queue to underlying scheduler */
@@ -196,6 +203,7 @@
} else {
q->latency = qopt->latency;
q->limit = qopt->limit;
+ q->loss = qopt->loss;
}
return err;
}
@@ -232,6 +240,7 @@
qopt.latency = q->latency;
qopt.limit = q->limit;
+ qopt.loss = q->loss;
RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
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