diff mbox series

[net-next,1/3] netem: convert to qdisc_watchdog_schedule_ns

Message ID 1510088376-5527-2-git-send-email-dave.taht@gmail.com
State Superseded, archived
Delegated to: David Miller
Headers show
Series netem: add nsec scheduling and slot feature | expand

Commit Message

Dave Taht Nov. 7, 2017, 8:59 p.m. UTC 
Upgrade the internal netem scheduler to use nanoseconds rather than
ticks throughout.

Convert to and from the std "ticks" userspace api automatically,
while allowing for finer grained scheduling to take place.

Signed-off-by: Dave Taht <dave.taht@gmail.com>
---
 net/sched/sch_netem.c | 56 +++++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 28 deletions(-)

Comments

James Hogan Nov. 14, 2017, 9:11 p.m. UTC | #1 
On Tue, Nov 07, 2017 at 12:59:34PM -0800, Dave Taht wrote:
> diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> index db0228a..443a75d 100644
> --- a/net/sched/sch_netem.c
> +++ b/net/sched/sch_netem.c

...

> @@ -305,11 +305,11 @@ static bool loss_event(struct netem_sched_data *q)
>   * std deviation sigma.  Uses table lookup to approximate the desired
>   * distribution, and a uniformly-distributed pseudo-random source.
>   */
> -static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
> -				struct crndstate *state,
> -				const struct disttable *dist)
> +static s64 tabledist(s64 mu, s64 sigma,

sigma is used in a modulo operation in this function, which results in
this error on a bunch of MIPS configs once it is made 64-bits wide:

net/sched/sch_netem.o In function `tabledist':
net/sched/sch_netem.c:330: undefined reference to `__moddi3'

Should that code not be using <linux/math64.h>, i.e. div_s64_rem() now
that it is 64bit?

Thanks
James
James Hogan Nov. 14, 2017, 9:43 p.m. UTC | #2 
On Tue, Nov 14, 2017 at 09:11:12PM +0000, James Hogan wrote:
> On Tue, Nov 07, 2017 at 12:59:34PM -0800, Dave Taht wrote:
> > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> > index db0228a..443a75d 100644
> > --- a/net/sched/sch_netem.c
> > +++ b/net/sched/sch_netem.c
> 
> ...
> 
> > @@ -305,11 +305,11 @@ static bool loss_event(struct netem_sched_data *q)
> >   * std deviation sigma.  Uses table lookup to approximate the desired
> >   * distribution, and a uniformly-distributed pseudo-random source.
> >   */
> > -static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
> > -				struct crndstate *state,
> > -				const struct disttable *dist)
> > +static s64 tabledist(s64 mu, s64 sigma,
> 
> sigma is used in a modulo operation in this function, which results in
> this error on a bunch of MIPS configs once it is made 64-bits wide:
> 
> net/sched/sch_netem.o In function `tabledist':
> net/sched/sch_netem.c:330: undefined reference to `__moddi3'
> 
> Should that code not be using <linux/math64.h>, i.e. div_s64_rem() now
> that it is 64bit?

For the record, Dave has kindly pointed me at:
https://patchwork.ozlabs.org/project/netdev/list/?series=13554

which fixes the MIPS builds.

Cheers
James
Stephen Hemminger Nov. 14, 2017, 10:49 p.m. UTC | #3 
On Tue, 14 Nov 2017 21:11:13 +0000
James Hogan <james.hogan@mips.com> wrote:

> On Tue, Nov 07, 2017 at 12:59:34PM -0800, Dave Taht wrote:
> > diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
> > index db0228a..443a75d 100644
> > --- a/net/sched/sch_netem.c
> > +++ b/net/sched/sch_netem.c  
> 
> ...
> 
> > @@ -305,11 +305,11 @@ static bool loss_event(struct netem_sched_data *q)
> >   * std deviation sigma.  Uses table lookup to approximate the desired
> >   * distribution, and a uniformly-distributed pseudo-random source.
> >   */
> > -static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
> > -				struct crndstate *state,
> > -				const struct disttable *dist)
> > +static s64 tabledist(s64 mu, s64 sigma,  
> 
> sigma is used in a modulo operation in this function, which results in
> this error on a bunch of MIPS configs once it is made 64-bits wide:
> 
> net/sched/sch_netem.o In function `tabledist':
> net/sched/sch_netem.c:330: undefined reference to `__moddi3'
> 
> Should that code not be using <linux/math64.h>, i.e. div_s64_rem() now
> that it is 64bit?
> 
> Thanks
> James

Not really since random is only 32 bit, the sigma value being 64 bit makes
no sense really.
diff mbox series

Patch

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index db0228a..443a75d 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -77,8 +77,8 @@  struct netem_sched_data {
 
 	struct qdisc_watchdog watchdog;
 
-	psched_tdiff_t latency;
-	psched_tdiff_t jitter;
+	s64 latency;
+	s64 jitter;
 
 	u32 loss;
 	u32 ecn;
@@ -145,7 +145,7 @@  struct netem_sched_data {
  * we save skb->tstamp value in skb->cb[] before destroying it.
  */
 struct netem_skb_cb {
-	psched_time_t	time_to_send;
+	u64	        time_to_send;
 };
 
 static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb)
@@ -305,11 +305,11 @@  static bool loss_event(struct netem_sched_data *q)
  * std deviation sigma.  Uses table lookup to approximate the desired
  * distribution, and a uniformly-distributed pseudo-random source.
  */
-static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
-				struct crndstate *state,
-				const struct disttable *dist)
+static s64 tabledist(s64 mu, s64 sigma,
+			 struct crndstate *state,
+			 const struct disttable *dist)
 {
-	psched_tdiff_t x;
+	s64 x;
 	long t;
 	u32 rnd;
 
@@ -332,10 +332,10 @@  static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
 	return  x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
 }
 
-static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sched_data *q)
+static s64 packet_len_2_sched_time(unsigned int len,
+				       struct netem_sched_data *q)
 {
-	u64 ticks;
-
+	s64 offset;
 	len += q->packet_overhead;
 
 	if (q->cell_size) {
@@ -345,11 +345,9 @@  static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
 			cells++;
 		len = cells * (q->cell_size + q->cell_overhead);
 	}
-
-	ticks = (u64)len * NSEC_PER_SEC;
-
-	do_div(ticks, q->rate);
-	return PSCHED_NS2TICKS(ticks);
+	offset = (s64)len * NSEC_PER_SEC;
+	do_div(offset, q->rate);
+	return offset;
 }
 
 static void tfifo_reset(struct Qdisc *sch)
@@ -369,7 +367,7 @@  static void tfifo_reset(struct Qdisc *sch)
 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 {
 	struct netem_sched_data *q = qdisc_priv(sch);
-	psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
+	u64 tnext = netem_skb_cb(nskb)->time_to_send;
 	struct rb_node **p = &q->t_root.rb_node, *parent = NULL;
 
 	while (*p) {
@@ -515,13 +513,13 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	if (q->gap == 0 ||		/* not doing reordering */
 	    q->counter < q->gap - 1 ||	/* inside last reordering gap */
 	    q->reorder < get_crandom(&q->reorder_cor)) {
-		psched_time_t now;
-		psched_tdiff_t delay;
+		u64 now;
+		s64 delay;
 
 		delay = tabledist(q->latency, q->jitter,
 				  &q->delay_cor, q->delay_dist);
 
-		now = psched_get_time();
+		now = ktime_get_ns();
 
 		if (q->rate) {
 			struct netem_skb_cb *last = NULL;
@@ -547,7 +545,7 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 				 * from delay.
 				 */
 				delay -= last->time_to_send - now;
-				delay = max_t(psched_tdiff_t, 0, delay);
+				delay = max_t(s64, 0, delay);
 				now = last->time_to_send;
 			}
 
@@ -562,7 +560,7 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		 * Do re-ordering by putting one out of N packets at the front
 		 * of the queue.
 		 */
-		cb->time_to_send = psched_get_time();
+		cb->time_to_send = ktime_get_ns();
 		q->counter = 0;
 
 		netem_enqueue_skb_head(&sch->q, skb);
@@ -609,13 +607,13 @@  static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 	}
 	p = rb_first(&q->t_root);
 	if (p) {
-		psched_time_t time_to_send;
+		u64 time_to_send;
 
 		skb = rb_to_skb(p);
 
 		/* if more time remaining? */
 		time_to_send = netem_skb_cb(skb)->time_to_send;
-		if (time_to_send <= psched_get_time()) {
+		if (time_to_send <= ktime_get_ns()) {
 			rb_erase(p, &q->t_root);
 
 			sch->q.qlen--;
@@ -659,7 +657,7 @@  static struct sk_buff *netem_dequeue(struct Qdisc *sch)
 			if (skb)
 				goto deliver;
 		}
-		qdisc_watchdog_schedule(&q->watchdog, time_to_send);
+		qdisc_watchdog_schedule_ns(&q->watchdog, time_to_send);
 	}
 
 	if (q->qdisc) {
@@ -888,8 +886,8 @@  static int netem_change(struct Qdisc *sch, struct nlattr *opt)
 
 	sch->limit = qopt->limit;
 
-	q->latency = qopt->latency;
-	q->jitter = qopt->jitter;
+	q->latency = PSCHED_TICKS2NS(qopt->latency);
+	q->jitter = PSCHED_TICKS2NS(qopt->jitter);
 	q->limit = qopt->limit;
 	q->gap = qopt->gap;
 	q->counter = 0;
@@ -1011,8 +1009,10 @@  static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 	struct tc_netem_corrupt corrupt;
 	struct tc_netem_rate rate;
 
-	qopt.latency = q->latency;
-	qopt.jitter = q->jitter;
+	qopt.latency = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->latency),
+			     UINT_MAX);
+	qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
+			    UINT_MAX);
 	qopt.limit = q->limit;
 	qopt.loss = q->loss;
 	qopt.gap = q->gap;