Hi!
I have created this patch to add a fixed delay on packet filtered by
netem. Soon I will send the patch to iproute2.
This patch comes from a need I have to delay all packets 50ms, beside
the actual delay setting, like 30ms +- 15 ms. This strike, IMMHO, a
missing point on gap reordering. If I set "gap 5 delay 10ms" every 5th
(10th, 15th, ...) packet to go to be sent immediately and every other
packet to be delayed by 10ms. This is ok, but I also need a "fixed"
delay of 50ms to be applied to all packets. Since netem can't be
nested with himself (so I can do a fixed delay), I needed this new
feature on netem.
This patch was create with linux kernel version 2.6.24.2.
I hope you like it, and it would be great if it goes shiped with the
next version of the kernel :-))
Regards,
Julio Kriger
--
--
>From the moment I picked your book up until I laid it down, I was
convulsed with laughter. Someday I intend reading it.
Groucho Marx
----------------------------
Julio Kriger
mailto:[EMAIL PROTECTED]
diff -Naur linux-2.6.24.2-old/include/linux/pkt_sched.h
linux-2.6.24.2-new/include/linux/pkt_sched.h
--- linux-2.6.24.2-old/include/linux/pkt_sched.h 2008-02-11
03:51:11.000000000 -0200
+++ linux-2.6.24.2-new/include/linux/pkt_sched.h 2008-02-24
11:48:13.000000000 -0200
@@ -452,6 +452,7 @@
__u32 gap; /* re-ordering gap (0 for none) */
__u32 duplicate; /* random packet dup (0=none ~0=100%) */
__u32 jitter; /* random jitter in latency (us) */
+ __u32 fixed_latency; /* fixed latency form netem */
};
struct tc_netem_corr
diff -Naur linux-2.6.24.2-old/net/sched/sch_netem.c
linux-2.6.24.2-new/net/sched/sch_netem.c
--- linux-2.6.24.2-old/net/sched/sch_netem.c 2008-02-11 03:51:11.000000000
-0200
+++ linux-2.6.24.2-new/net/sched/sch_netem.c 2008-02-24 11:47:40.000000000
-0200
@@ -23,7 +23,7 @@
#include <net/netlink.h>
#include <net/pkt_sched.h>
-#define VERSION "1.2"
+#define VERSION "1.2.1"
/* Network Emulation Queuing algorithm.
====================================
@@ -65,6 +65,7 @@
u32 duplicate;
u32 reorder;
u32 corrupt;
+ u32 fixed_latency; /* handle fixed delay */
struct crndstate {
u32 last;
@@ -215,6 +216,13 @@
delay = tabledist(q->latency, q->jitter,
&q->delay_cor, q->delay_dist);
+ /*
+ * Add fixed delay
+ */
+ if(q->fixed_latency > 0) {
+ delay += tabledist(q->fixed_latency, 0, &q->delay_cor,
q->delay_dist);
+ }
+
now = psched_get_time();
cb->time_to_send = now + delay;
++q->counter;
@@ -225,6 +233,18 @@
* of the queue.
*/
cb->time_to_send = psched_get_time();
+
+ /*
+ * Add fixed delay
+ */
+ if(q->fixed_latency > 0) {
+ psched_time_t now;
+ psched_tdiff_t fixed_delay;
+ fixed_delay = tabledist(q->fixed_latency, 0,
&q->delay_cor, q->delay_dist);
+ now = psched_get_time();
+ cb->time_to_send = now + fixed_delay;
+ }
+
q->counter = 0;
ret = q->qdisc->ops->requeue(skb, q->qdisc);
}
@@ -427,6 +447,7 @@
q->counter = 0;
q->loss = qopt->loss;
q->duplicate = qopt->duplicate;
+ q->fixed_latency = qopt->fixed_latency;
/* for compatibility with earlier versions.
* if gap is set, need to assume 100% probability
@@ -607,6 +628,7 @@
qopt.loss = q->loss;
qopt.gap = q->gap;
qopt.duplicate = q->duplicate;
+ qopt.fixed_latency = q->fixed_latency;
RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
cor.delay_corr = q->delay_cor.rho;
