pkt_sched: sch_htb: Use workqueue to schedule after too many events.
Patrick McHardy <kaber@trash.net> suggested using a workqueue instead
of hrtimers to trigger netif_schedule() when there is a problem with
setting exact time of this event: 'The differnce - yeah, it shouldn't
make much, mainly wake up the qdisc earlier (but not too early) after
"too many events" occured _and_ no further enqueue events wake up the
qdisc anyways.'
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 826f921..355974f 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -35,6 +35,7 @@
#include <linux/list.h>
#include <linux/compiler.h>
#include <linux/rbtree.h>
+#include <linux/workqueue.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
@@ -156,6 +157,7 @@
#define HTB_WARN_TOOMANYEVENTS 0x1
unsigned int warned; /* only one warning */
+ struct work_struct work;
};
/* find class in global hash table using given handle */
@@ -659,7 +661,7 @@
* htb_do_events - make mode changes to classes at the level
*
* Scans event queue for pending events and applies them. Returns time of
- * next pending event (0 for no event in pq).
+ * next pending event (0 for no event in pq, q->now for too many events).
* Note: Applied are events whose have cl->pq_key <= q->now.
*/
static psched_time_t htb_do_events(struct htb_sched *q, int level,
@@ -687,12 +689,14 @@
if (cl->cmode != HTB_CAN_SEND)
htb_add_to_wait_tree(q, cl, diff);
}
- /* too much load - let's continue on next jiffie (including above) */
+
+ /* too much load - let's continue after a break for scheduling */
if (!(q->warned & HTB_WARN_TOOMANYEVENTS)) {
printk(KERN_WARNING "htb: too many events!\n");
q->warned |= HTB_WARN_TOOMANYEVENTS;
}
- return q->now + 2 * PSCHED_TICKS_PER_SEC / HZ;
+
+ return q->now;
}
/* Returns class->node+prio from id-tree where classe's id is >= id. NULL
@@ -892,7 +896,10 @@
}
}
sch->qstats.overlimits++;
- qdisc_watchdog_schedule(&q->watchdog, next_event);
+ if (likely(next_event > q->now))
+ qdisc_watchdog_schedule(&q->watchdog, next_event);
+ else
+ schedule_work(&q->work);
fin:
return skb;
}
@@ -962,6 +969,14 @@
[TCA_HTB_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
};
+static void htb_work_func(struct work_struct *work)
+{
+ struct htb_sched *q = container_of(work, struct htb_sched, work);
+ struct Qdisc *sch = q->watchdog.qdisc;
+
+ __netif_schedule(qdisc_root(sch));
+}
+
static int htb_init(struct Qdisc *sch, struct nlattr *opt)
{
struct htb_sched *q = qdisc_priv(sch);
@@ -996,6 +1011,7 @@
INIT_LIST_HEAD(q->drops + i);
qdisc_watchdog_init(&q->watchdog, sch);
+ INIT_WORK(&q->work, htb_work_func);
skb_queue_head_init(&q->direct_queue);
q->direct_qlen = qdisc_dev(sch)->tx_queue_len;
@@ -1188,7 +1204,6 @@
kfree(cl);
}
-/* always caled under BH & queue lock */
static void htb_destroy(struct Qdisc *sch)
{
struct htb_sched *q = qdisc_priv(sch);
@@ -1196,6 +1211,7 @@
struct htb_class *cl;
unsigned int i;
+ cancel_work_sync(&q->work);
qdisc_watchdog_cancel(&q->watchdog);
/* This line used to be after htb_destroy_class call below
and surprisingly it worked in 2.4. But it must precede it