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authorEric Dumazet <edumazet@google.com>2013-06-15 03:30:10 -0700
committerDavid S. Miller <davem@davemloft.net>2013-06-19 23:06:52 -0700
commitc9364636dcb01a6fc37ca2c6a51c5aa0c663013c (patch)
tree4ea94902a65b0f3ca46ec82652da39b0dea59d55 /net/sched
parentbcefe17cffd06efdda3e7ad679ea743236e6271a (diff)
downloadlinux-c9364636dcb01a6fc37ca2c6a51c5aa0c663013c.tar.bz2
htb: refactor struct htb_sched fields for performance
htb_sched structures are big, and source of false sharing on SMP. Every time a packet is queued or dequeue, many cache lines must be touched because structures are not lay out properly. By carefully splitting htb_sched in two parts, and define sub structures to increase data locality, we can improve performance dramatically on SMP. New htb_prio structure can also be used in htb_class to increase data locality. I got 26 % performance increase on a 24 threads machine, with 200 concurrent netperf in TCP_RR mode, using a HTB hierarchy of 4 classes. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/sch_htb.c181
1 files changed, 95 insertions, 86 deletions
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 7954e73d118a..c2124ea29f45 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -76,6 +76,20 @@ enum htb_cmode {
HTB_CAN_SEND /* class can send */
};
+struct htb_prio {
+ union {
+ struct rb_root row;
+ struct rb_root feed;
+ };
+ struct rb_node *ptr;
+ /* When class changes from state 1->2 and disconnects from
+ * parent's feed then we lost ptr value and start from the
+ * first child again. Here we store classid of the
+ * last valid ptr (used when ptr is NULL).
+ */
+ u32 last_ptr_id;
+};
+
/* interior & leaf nodes; props specific to leaves are marked L:
* To reduce false sharing, place mostly read fields at beginning,
* and mostly written ones at the end.
@@ -112,19 +126,12 @@ struct htb_class {
union {
struct htb_class_leaf {
- struct Qdisc *q;
- int deficit[TC_HTB_MAXDEPTH];
struct list_head drop_list;
+ int deficit[TC_HTB_MAXDEPTH];
+ struct Qdisc *q;
} leaf;
struct htb_class_inner {
- struct rb_root feed[TC_HTB_NUMPRIO]; /* feed trees */
- struct rb_node *ptr[TC_HTB_NUMPRIO]; /* current class ptr */
- /* When class changes from state 1->2 and disconnects from
- * parent's feed then we lost ptr value and start from the
- * first child again. Here we store classid of the
- * last valid ptr (used when ptr is NULL).
- */
- u32 last_ptr_id[TC_HTB_NUMPRIO];
+ struct htb_prio clprio[TC_HTB_NUMPRIO];
} inner;
} un;
s64 pq_key;
@@ -135,40 +142,39 @@ struct htb_class {
struct rb_node node[TC_HTB_NUMPRIO]; /* node for self or feed tree */
};
+struct htb_level {
+ struct rb_root wait_pq;
+ struct htb_prio hprio[TC_HTB_NUMPRIO];
+};
+
struct htb_sched {
struct Qdisc_class_hash clhash;
- struct list_head drops[TC_HTB_NUMPRIO];/* active leaves (for drops) */
-
- /* self list - roots of self generating tree */
- struct rb_root row[TC_HTB_MAXDEPTH][TC_HTB_NUMPRIO];
- int row_mask[TC_HTB_MAXDEPTH];
- struct rb_node *ptr[TC_HTB_MAXDEPTH][TC_HTB_NUMPRIO];
- u32 last_ptr_id[TC_HTB_MAXDEPTH][TC_HTB_NUMPRIO];
+ int defcls; /* class where unclassified flows go to */
+ int rate2quantum; /* quant = rate / rate2quantum */
- /* self wait list - roots of wait PQs per row */
- struct rb_root wait_pq[TC_HTB_MAXDEPTH];
+ /* filters for qdisc itself */
+ struct tcf_proto *filter_list;
- /* time of nearest event per level (row) */
- s64 near_ev_cache[TC_HTB_MAXDEPTH];
+#define HTB_WARN_TOOMANYEVENTS 0x1
+ unsigned int warned; /* only one warning */
+ int direct_qlen;
+ struct work_struct work;
- int defcls; /* class where unclassified flows go to */
+ /* non shaped skbs; let them go directly thru */
+ struct sk_buff_head direct_queue;
+ long direct_pkts;
- /* filters for qdisc itself */
- struct tcf_proto *filter_list;
+ struct qdisc_watchdog watchdog;
- int rate2quantum; /* quant = rate / rate2quantum */
- s64 now; /* cached dequeue time */
- struct qdisc_watchdog watchdog;
+ s64 now; /* cached dequeue time */
+ struct list_head drops[TC_HTB_NUMPRIO];/* active leaves (for drops) */
- /* non shaped skbs; let them go directly thru */
- struct sk_buff_head direct_queue;
- int direct_qlen; /* max qlen of above */
+ /* time of nearest event per level (row) */
+ s64 near_ev_cache[TC_HTB_MAXDEPTH];
- long direct_pkts;
+ int row_mask[TC_HTB_MAXDEPTH];
-#define HTB_WARN_TOOMANYEVENTS 0x1
- unsigned int warned; /* only one warning */
- struct work_struct work;
+ struct htb_level hlevel[TC_HTB_MAXDEPTH];
};
/* find class in global hash table using given handle */
@@ -284,7 +290,7 @@ static void htb_add_to_id_tree(struct rb_root *root,
static void htb_add_to_wait_tree(struct htb_sched *q,
struct htb_class *cl, s64 delay)
{
- struct rb_node **p = &q->wait_pq[cl->level].rb_node, *parent = NULL;
+ struct rb_node **p = &q->hlevel[cl->level].wait_pq.rb_node, *parent = NULL;
cl->pq_key = q->now + delay;
if (cl->pq_key == q->now)
@@ -304,7 +310,7 @@ static void htb_add_to_wait_tree(struct htb_sched *q,
p = &parent->rb_left;
}
rb_link_node(&cl->pq_node, parent, p);
- rb_insert_color(&cl->pq_node, &q->wait_pq[cl->level]);
+ rb_insert_color(&cl->pq_node, &q->hlevel[cl->level].wait_pq);
}
/**
@@ -331,7 +337,7 @@ static inline void htb_add_class_to_row(struct htb_sched *q,
while (mask) {
int prio = ffz(~mask);
mask &= ~(1 << prio);
- htb_add_to_id_tree(q->row[cl->level] + prio, cl, prio);
+ htb_add_to_id_tree(&q->hlevel[cl->level].hprio[prio].row, cl, prio);
}
}
@@ -357,16 +363,18 @@ static inline void htb_remove_class_from_row(struct htb_sched *q,
struct htb_class *cl, int mask)
{
int m = 0;
+ struct htb_level *hlevel = &q->hlevel[cl->level];
while (mask) {
int prio = ffz(~mask);
+ struct htb_prio *hprio = &hlevel->hprio[prio];
mask &= ~(1 << prio);
- if (q->ptr[cl->level][prio] == cl->node + prio)
- htb_next_rb_node(q->ptr[cl->level] + prio);
+ if (hprio->ptr == cl->node + prio)
+ htb_next_rb_node(&hprio->ptr);
- htb_safe_rb_erase(cl->node + prio, q->row[cl->level] + prio);
- if (!q->row[cl->level][prio].rb_node)
+ htb_safe_rb_erase(cl->node + prio, &hprio->row);
+ if (!hprio->row.rb_node)
m |= 1 << prio;
}
q->row_mask[cl->level] &= ~m;
@@ -390,13 +398,13 @@ static void htb_activate_prios(struct htb_sched *q, struct htb_class *cl)
int prio = ffz(~m);
m &= ~(1 << prio);
- if (p->un.inner.feed[prio].rb_node)
+ if (p->un.inner.clprio[prio].feed.rb_node)
/* parent already has its feed in use so that
* reset bit in mask as parent is already ok
*/
mask &= ~(1 << prio);
- htb_add_to_id_tree(p->un.inner.feed + prio, cl, prio);
+ htb_add_to_id_tree(&p->un.inner.clprio[prio].feed, cl, prio);
}
p->prio_activity |= mask;
cl = p;
@@ -426,18 +434,19 @@ static void htb_deactivate_prios(struct htb_sched *q, struct htb_class *cl)
int prio = ffz(~m);
m &= ~(1 << prio);
- if (p->un.inner.ptr[prio] == cl->node + prio) {
+ if (p->un.inner.clprio[prio].ptr == cl->node + prio) {
/* we are removing child which is pointed to from
* parent feed - forget the pointer but remember
* classid
*/
- p->un.inner.last_ptr_id[prio] = cl->common.classid;
- p->un.inner.ptr[prio] = NULL;
+ p->un.inner.clprio[prio].last_ptr_id = cl->common.classid;
+ p->un.inner.clprio[prio].ptr = NULL;
}
- htb_safe_rb_erase(cl->node + prio, p->un.inner.feed + prio);
+ htb_safe_rb_erase(cl->node + prio,
+ &p->un.inner.clprio[prio].feed);
- if (!p->un.inner.feed[prio].rb_node)
+ if (!p->un.inner.clprio[prio].feed.rb_node)
mask |= 1 << prio;
}
@@ -652,7 +661,7 @@ static void htb_charge_class(struct htb_sched *q, struct htb_class *cl,
htb_change_class_mode(q, cl, &diff);
if (old_mode != cl->cmode) {
if (old_mode != HTB_CAN_SEND)
- htb_safe_rb_erase(&cl->pq_node, q->wait_pq + cl->level);
+ htb_safe_rb_erase(&cl->pq_node, &q->hlevel[cl->level].wait_pq);
if (cl->cmode != HTB_CAN_SEND)
htb_add_to_wait_tree(q, cl, diff);
}
@@ -672,7 +681,7 @@ static void htb_charge_class(struct htb_sched *q, struct htb_class *cl,
* 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 s64 htb_do_events(struct htb_sched *q, int level,
+static s64 htb_do_events(struct htb_sched *q, const int level,
unsigned long start)
{
/* don't run for longer than 2 jiffies; 2 is used instead of
@@ -680,10 +689,12 @@ static s64 htb_do_events(struct htb_sched *q, int level,
* too soon
*/
unsigned long stop_at = start + 2;
+ struct rb_root *wait_pq = &q->hlevel[level].wait_pq;
+
while (time_before(jiffies, stop_at)) {
struct htb_class *cl;
s64 diff;
- struct rb_node *p = rb_first(&q->wait_pq[level]);
+ struct rb_node *p = rb_first(wait_pq);
if (!p)
return 0;
@@ -692,7 +703,7 @@ static s64 htb_do_events(struct htb_sched *q, int level,
if (cl->pq_key > q->now)
return cl->pq_key;
- htb_safe_rb_erase(p, q->wait_pq + level);
+ htb_safe_rb_erase(p, wait_pq);
diff = min_t(s64, q->now - cl->t_c, cl->mbuffer);
htb_change_class_mode(q, cl, &diff);
if (cl->cmode != HTB_CAN_SEND)
@@ -736,8 +747,7 @@ static struct rb_node *htb_id_find_next_upper(int prio, struct rb_node *n,
*
* Find leaf where current feed pointers points to.
*/
-static struct htb_class *htb_lookup_leaf(struct rb_root *tree, int prio,
- struct rb_node **pptr, u32 * pid)
+static struct htb_class *htb_lookup_leaf(struct htb_prio *hprio, const int prio)
{
int i;
struct {
@@ -746,10 +756,10 @@ static struct htb_class *htb_lookup_leaf(struct rb_root *tree, int prio,
u32 *pid;
} stk[TC_HTB_MAXDEPTH], *sp = stk;
- BUG_ON(!tree->rb_node);
- sp->root = tree->rb_node;
- sp->pptr = pptr;
- sp->pid = pid;
+ BUG_ON(!hprio->row.rb_node);
+ sp->root = hprio->row.rb_node;
+ sp->pptr = &hprio->ptr;
+ sp->pid = &hprio->last_ptr_id;
for (i = 0; i < 65535; i++) {
if (!*sp->pptr && *sp->pid) {
@@ -776,12 +786,15 @@ static struct htb_class *htb_lookup_leaf(struct rb_root *tree, int prio,
}
} else {
struct htb_class *cl;
+ struct htb_prio *clp;
+
cl = rb_entry(*sp->pptr, struct htb_class, node[prio]);
if (!cl->level)
return cl;
- (++sp)->root = cl->un.inner.feed[prio].rb_node;
- sp->pptr = cl->un.inner.ptr + prio;
- sp->pid = cl->un.inner.last_ptr_id + prio;
+ clp = &cl->un.inner.clprio[prio];
+ (++sp)->root = clp->feed.rb_node;
+ sp->pptr = &clp->ptr;
+ sp->pid = &clp->last_ptr_id;
}
}
WARN_ON(1);
@@ -791,15 +804,16 @@ static struct htb_class *htb_lookup_leaf(struct rb_root *tree, int prio,
/* dequeues packet at given priority and level; call only if
* you are sure that there is active class at prio/level
*/
-static struct sk_buff *htb_dequeue_tree(struct htb_sched *q, int prio,
- int level)
+static struct sk_buff *htb_dequeue_tree(struct htb_sched *q, const int prio,
+ const int level)
{
struct sk_buff *skb = NULL;
struct htb_class *cl, *start;
+ struct htb_level *hlevel = &q->hlevel[level];
+ struct htb_prio *hprio = &hlevel->hprio[prio];
+
/* look initial class up in the row */
- start = cl = htb_lookup_leaf(q->row[level] + prio, prio,
- q->ptr[level] + prio,
- q->last_ptr_id[level] + prio);
+ start = cl = htb_lookup_leaf(hprio, prio);
do {
next:
@@ -819,9 +833,7 @@ next:
if ((q->row_mask[level] & (1 << prio)) == 0)
return NULL;
- next = htb_lookup_leaf(q->row[level] + prio,
- prio, q->ptr[level] + prio,
- q->last_ptr_id[level] + prio);
+ next = htb_lookup_leaf(hprio, prio);
if (cl == start) /* fix start if we just deleted it */
start = next;
@@ -834,11 +846,9 @@ next:
break;
qdisc_warn_nonwc("htb", cl->un.leaf.q);
- htb_next_rb_node((level ? cl->parent->un.inner.ptr : q->
- ptr[0]) + prio);
- cl = htb_lookup_leaf(q->row[level] + prio, prio,
- q->ptr[level] + prio,
- q->last_ptr_id[level] + prio);
+ htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr:
+ &q->hlevel[0].hprio[prio].ptr);
+ cl = htb_lookup_leaf(hprio, prio);
} while (cl != start);
@@ -847,8 +857,8 @@ next:
cl->un.leaf.deficit[level] -= qdisc_pkt_len(skb);
if (cl->un.leaf.deficit[level] < 0) {
cl->un.leaf.deficit[level] += cl->quantum;
- htb_next_rb_node((level ? cl->parent->un.inner.ptr : q->
- ptr[0]) + prio);
+ htb_next_rb_node(level ? &cl->parent->un.inner.clprio[prio].ptr :
+ &q->hlevel[0].hprio[prio].ptr);
}
/* this used to be after charge_class but this constelation
* gives us slightly better performance
@@ -888,15 +898,14 @@ ok:
for (level = 0; level < TC_HTB_MAXDEPTH; level++) {
/* common case optimization - skip event handler quickly */
int m;
- s64 event;
+ s64 event = q->near_ev_cache[level];
- if (q->now >= q->near_ev_cache[level]) {
+ if (q->now >= event) {
event = htb_do_events(q, level, start_at);
if (!event)
event = q->now + NSEC_PER_SEC;
q->near_ev_cache[level] = event;
- } else
- event = q->near_ev_cache[level];
+ }
if (next_event > event)
next_event = event;
@@ -976,10 +985,8 @@ static void htb_reset(struct Qdisc *sch)
qdisc_watchdog_cancel(&q->watchdog);
__skb_queue_purge(&q->direct_queue);
sch->q.qlen = 0;
- memset(q->row, 0, sizeof(q->row));
+ memset(q->hlevel, 0, sizeof(q->hlevel));
memset(q->row_mask, 0, sizeof(q->row_mask));
- memset(q->wait_pq, 0, sizeof(q->wait_pq));
- memset(q->ptr, 0, sizeof(q->ptr));
for (i = 0; i < TC_HTB_NUMPRIO; i++)
INIT_LIST_HEAD(q->drops + i);
}
@@ -1200,7 +1207,8 @@ static void htb_parent_to_leaf(struct htb_sched *q, struct htb_class *cl,
WARN_ON(cl->level || !cl->un.leaf.q || cl->prio_activity);
if (parent->cmode != HTB_CAN_SEND)
- htb_safe_rb_erase(&parent->pq_node, q->wait_pq + parent->level);
+ htb_safe_rb_erase(&parent->pq_node,
+ &q->hlevel[parent->level].wait_pq);
parent->level = 0;
memset(&parent->un.inner, 0, sizeof(parent->un.inner));
@@ -1289,7 +1297,8 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg)
htb_deactivate(q, cl);
if (cl->cmode != HTB_CAN_SEND)
- htb_safe_rb_erase(&cl->pq_node, q->wait_pq + cl->level);
+ htb_safe_rb_erase(&cl->pq_node,
+ &q->hlevel[cl->level].wait_pq);
if (last_child)
htb_parent_to_leaf(q, cl, new_q);
@@ -1411,7 +1420,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
/* remove from evt list because of level change */
if (parent->cmode != HTB_CAN_SEND) {
- htb_safe_rb_erase(&parent->pq_node, q->wait_pq);
+ htb_safe_rb_erase(&parent->pq_node, &q->hlevel[0].wait_pq);
parent->cmode = HTB_CAN_SEND;
}
parent->level = (parent->parent ? parent->parent->level