Extend slotting with support for non-uniform distributions. This is
similar to netem's non-uniform distribution delay feature.
Syntax:
slot distribution DISTRIBUTION DELAY JITTER [packets MAX_PACKETS] \
[bytes MAX_BYTES]
The syntax and use of the distribution table is the same as in the
non-uniform distribution delay feature. A file DISTRIBUTION must be
present in TC_LIB_DIR (e.g. /usr/lib/tc) containing numbers scaled by
NETEM_DIST_SCALE. A random value x is selected from the table and it
takes DELAY + ( x * JITTER ) as delay. Correlation between values is not
supported.
Examples:
Normal distribution delay with mean = 800us and stdev = 100us.
> tc qdisc add dev eth0 root netem slot distribution normal \
800us 100us
Optionally set the max slot size in bytes and/or packets.
> tc qdisc add dev eth0 root netem slot distribution normal \
800us 100us bytes 64k packets 42
Signed-off-by: Yousuk Seung <ysse...@google.com>
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Dave Taht <dave.t...@gmail.com>
---
man/man8/tc-netem.8 | 20 ++++++++----
tc/q_netem.c | 75 +++++++++++++++++++++++++++++++++++++--------
2 files changed, 76 insertions(+), 19 deletions(-)
diff --git a/man/man8/tc-netem.8 b/man/man8/tc-netem.8
index 8d485b026751..111109cf042f 100644
--- a/man/man8/tc-netem.8
+++ b/man/man8/tc-netem.8
@@ -53,9 +53,13 @@ NetEm \- Network Emulator
.IR RATE " [ " PACKETOVERHEAD " [ " CELLSIZE " [ " CELLOVERHEAD " ]]]]"
.IR SLOT " := "
-.BR slot
-.IR MIN_DELAY " [ " MAX_DELAY " ] ["
-.BR packets
+.BR slot " { "
+.IR MIN_DELAY " [ " MAX_DELAY " ] |"
+.br
+.RB " " distribution " { "uniform " | " normal " | " pareto " |
" paretonormal " | "
+.IR FILE " } " DELAY " " JITTER " } "
+.br
+.RB " [ " packets
.IR PACKETS " ] [ "
.BR bytes
.IR BYTES " ]"
@@ -172,9 +176,13 @@ an artificial packet compression (bursts). Another
influence factor are network
adapter buffers which can also add artificial delay.
.SS slot
-defer delivering accumulated packets to within a slot, with each available slot
-configured with a minimum delay to acquire, and an optional maximum delay.
Slot
-delays can be specified in nanoseconds, microseconds, milliseconds or seconds
+defer delivering accumulated packets to within a slot. Each available slot can
be
+configured with a minimum delay to acquire, and an optional maximum delay.
+Alternatively it can be configured with the distribution similar to
+.BR distribution
+for
+.BR delay
+option. Slot delays can be specified in nanoseconds, microseconds,
milliseconds or seconds
(e.g. 800us). Values for the optional parameters
.I BYTES
will limit the number of bytes delivered per slot, and/or
diff --git a/tc/q_netem.c b/tc/q_netem.c
index f52a36b6c31c..e655e1a82e12 100644
--- a/tc/q_netem.c
+++ b/tc/q_netem.c
@@ -43,7 +43,9 @@ static void explain(void)
" [ rate RATE [PACKETOVERHEAD] [CELLSIZE] [CELLOVERHEAD]]\n" \
" [ slot MIN_DELAY [MAX_DELAY] [packets MAX_PACKETS]" \
" [bytes MAX_BYTES]]\n" \
- );
+" [ slot distribution" \
+" {uniform|normal|pareto|paretonormal|custom} DELAY JITTER" \
+" [packets MAX_PACKETS] [bytes MAX_BYTES]]\n");
}
static void explain1(const char *arg)
@@ -159,6 +161,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc,
char **argv,
struct nlmsghdr *n, const char *dev)
{
int dist_size = 0;
+ int slot_dist_size = 0;
struct rtattr *tail;
struct tc_netem_qopt opt = { .limit = 1000 };
struct tc_netem_corr cor = {};
@@ -169,6 +172,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc,
char **argv,
struct tc_netem_rate rate = {};
struct tc_netem_slot slot = {};
__s16 *dist_data = NULL;
+ __s16 *slot_dist_data = NULL;
__u16 loss_type = NETEM_LOSS_UNSPEC;
int present[__TCA_NETEM_MAX] = {};
__u64 rate64 = 0;
@@ -417,21 +421,53 @@ static int netem_parse_opt(struct qdisc_util *qu, int
argc, char **argv,
}
}
} else if (matches(*argv, "slot") == 0) {
- NEXT_ARG();
- present[TCA_NETEM_SLOT] = 1;
- if (get_time64(&slot.min_delay, *argv)) {
- explain1("slot min_delay");
- return -1;
- }
if (NEXT_IS_NUMBER()) {
NEXT_ARG();
- if (get_time64(&slot.max_delay, *argv)) {
- explain1("slot min_delay max_delay");
+ present[TCA_NETEM_SLOT] = 1;
+ if (get_time64(&slot.min_delay, *argv)) {
+ explain1("slot min_delay");
+ return -1;
+ }
+ if (NEXT_IS_NUMBER()) {
+ NEXT_ARG();
+ if (get_time64(&slot.max_delay, *argv))
{
+ explain1("slot min_delay
max_delay");
+ return -1;
+ }
+ }
+ if (slot.max_delay < slot.min_delay)
+ slot.max_delay = slot.min_delay;
+ } else {
+ NEXT_ARG();
+ if (strcmp(*argv, "distribution") == 0) {
+ present[TCA_NETEM_SLOT] = 1;
+ NEXT_ARG();
+ slot_dist_data =
calloc(sizeof(slot_dist_data[0]), MAX_DIST);
+ slot_dist_size =
get_distribution(*argv, slot_dist_data, MAX_DIST);
+ if (slot_dist_size <= 0) {
+ free(slot_dist_data);
+ return -1;
+ }
+ NEXT_ARG();
+ if (get_time64(&slot.dist_delay,
*argv)) {
+ explain1("slot delay");
+ return -1;
+ }
+ NEXT_ARG();
+ if (get_time64(&slot.dist_jitter,
*argv)) {
+ explain1("slot jitter");
+ return -1;
+ }
+ if (slot.dist_jitter <= 0) {
+ fprintf(stderr, "Non-positive
jitter\n");
+ return -1;
+ }
+ } else {
+ fprintf(stderr, "Unknown slot
parameter: %s\n",
+ *argv);
return -1;
}
}
- if (slot.max_delay < slot.min_delay)
- slot.max_delay = slot.min_delay;
if (NEXT_ARG_OK() &&
matches(*(argv+1), "packets") == 0) {
NEXT_ARG();
@@ -558,6 +594,14 @@ static int netem_parse_opt(struct qdisc_util *qu, int
argc, char **argv,
return -1;
free(dist_data);
}
+
+ if (slot_dist_data) {
+ if (addattr_l(n, MAX_DIST * sizeof(slot_dist_data[0]),
+ TCA_NETEM_SLOT_DIST,
+ slot_dist_data, slot_dist_size *
sizeof(slot_dist_data[0])) < 0)
+ return -1;
+ free(slot_dist_data);
+ }
tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
return 0;
}
@@ -712,8 +756,13 @@ static int netem_print_opt(struct qdisc_util *qu, FILE *f,
struct rtattr *opt)
}
if (slot) {
- fprintf(f, " slot %s", sprint_time64(slot->min_delay, b1));
- fprintf(f, " %s", sprint_time64(slot->max_delay, b1));
+ if (slot->dist_jitter > 0) {
+ fprintf(f, " slot distribution %s",
sprint_time64(slot->dist_delay, b1));
+ fprintf(f, " %s", sprint_time64(slot->dist_jitter, b1));
+ } else {
+ fprintf(f, " slot %s", sprint_time64(slot->min_delay, b1));
+ fprintf(f, " %s", sprint_time64(slot->max_delay, b1));
+ }
if(slot->max_packets)
fprintf(f, " packets %d", slot->max_packets);
if(slot->max_bytes)
--
2.18.0.597.ga71716f1ad-goog
