From c9364636dcb01a6fc37ca2c6a51c5aa0c663013c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 15 Jun 2013 03:30:10 -0700 Subject: [PATCH] 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 Cc: Tom Herbert Signed-off-by: David S. Miller --- net/sched/sch_htb.c | 181 +++++++++++++++++++++++--------------------- 1 file 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 -- 2.30.2