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Date: Tue, 1 Oct 2019 19:06:42 -0700
From: Pravin Shelar <pshelar@....org>
To: Tonghao Zhang <xiangxia.m.yue@...il.com>
Cc: Greg Rose <gvrose8192@...il.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 2/9] net: openvswitch: convert mask list in mask array
On Sun, Sep 29, 2019 at 7:09 PM <xiangxia.m.yue@...il.com> wrote:
>
> From: Tonghao Zhang <xiangxia.m.yue@...il.com>
>
> Port the codes to linux upstream and with little changes.
>
> Pravin B Shelar, says:
> | mask caches index of mask in mask_list. On packet recv OVS
> | need to traverse mask-list to get cached mask. Therefore array
> | is better for retrieving cached mask. This also allows better
> | cache replacement algorithm by directly checking mask's existence.
>
> Link: https://github.com/openvswitch/ovs/commit/d49fc3ff53c65e4eca9cabd52ac63396746a7ef5
> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@...il.com>
> ---
> net/openvswitch/flow.h | 1 -
> net/openvswitch/flow_table.c | 218 +++++++++++++++++++++++++++++++++----------
> net/openvswitch/flow_table.h | 8 +-
> 3 files changed, 175 insertions(+), 52 deletions(-)
>
> diff --git a/net/openvswitch/flow.h b/net/openvswitch/flow.h
> index b830d5f..8080518 100644
> --- a/net/openvswitch/flow.h
> +++ b/net/openvswitch/flow.h
> @@ -166,7 +166,6 @@ struct sw_flow_key_range {
> struct sw_flow_mask {
> int ref_count;
> struct rcu_head rcu;
> - struct list_head list;
> struct sw_flow_key_range range;
> struct sw_flow_key key;
> };
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 3d515c0..99954fa 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -34,6 +34,7 @@
> #include <net/ndisc.h>
>
> #define TBL_MIN_BUCKETS 1024
> +#define MASK_ARRAY_SIZE_MIN 16
> #define REHASH_INTERVAL (10 * 60 * HZ)
>
> #define MC_HASH_SHIFT 8
> @@ -168,9 +169,59 @@ static struct table_instance *table_instance_alloc(int new_size)
> return ti;
> }
>
> +static void mask_array_rcu_cb(struct rcu_head *rcu)
> +{
> + struct mask_array *ma = container_of(rcu, struct mask_array, rcu);
> +
> + kfree(ma);
> +}
> +
> +static struct mask_array *tbl_mask_array_alloc(int size)
> +{
> + struct mask_array *new;
> +
> + size = max(MASK_ARRAY_SIZE_MIN, size);
> + new = kzalloc(sizeof(struct mask_array) +
> + sizeof(struct sw_flow_mask *) * size, GFP_KERNEL);
> + if (!new)
> + return NULL;
> +
> + new->count = 0;
> + new->max = size;
> +
> + return new;
> +}
> +
> +static int tbl_mask_array_realloc(struct flow_table *tbl, int size)
> +{
> + struct mask_array *old;
> + struct mask_array *new;
> +
> + new = tbl_mask_array_alloc(size);
> + if (!new)
> + return -ENOMEM;
> +
> + old = ovsl_dereference(tbl->mask_array);
> + if (old) {
> + int i;
> +
> + for (i = 0; i < old->max; i++) {
> + if (ovsl_dereference(old->masks[i]))
> + new->masks[new->count++] = old->masks[i];
> + }
> + }
> + rcu_assign_pointer(tbl->mask_array, new);
> +
> + if (old)
> + call_rcu(&old->rcu, mask_array_rcu_cb);
> +
kfree_rcu can be used instead of call_rcu.
> + return 0;
> +}
> +
> int ovs_flow_tbl_init(struct flow_table *table)
> {
> struct table_instance *ti, *ufid_ti;
> + struct mask_array *ma;
>
> table->mask_cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
> MC_HASH_ENTRIES,
> @@ -178,9 +229,13 @@ int ovs_flow_tbl_init(struct flow_table *table)
> if (!table->mask_cache)
> return -ENOMEM;
>
> + ma = tbl_mask_array_alloc(MASK_ARRAY_SIZE_MIN);
> + if (!ma)
> + goto free_mask_cache;
> +
> ti = table_instance_alloc(TBL_MIN_BUCKETS);
> if (!ti)
> - goto free_mask_cache;
> + goto free_mask_array;
>
> ufid_ti = table_instance_alloc(TBL_MIN_BUCKETS);
> if (!ufid_ti)
> @@ -188,7 +243,7 @@ int ovs_flow_tbl_init(struct flow_table *table)
>
> rcu_assign_pointer(table->ti, ti);
> rcu_assign_pointer(table->ufid_ti, ufid_ti);
> - INIT_LIST_HEAD(&table->mask_list);
> + rcu_assign_pointer(table->mask_array, ma);
> table->last_rehash = jiffies;
> table->count = 0;
> table->ufid_count = 0;
> @@ -196,6 +251,8 @@ int ovs_flow_tbl_init(struct flow_table *table)
>
> free_ti:
> __table_instance_destroy(ti);
> +free_mask_array:
> + kfree(ma);
> free_mask_cache:
> free_percpu(table->mask_cache);
> return -ENOMEM;
> @@ -255,6 +312,7 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
> struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
>
> free_percpu(table->mask_cache);
> + kfree(rcu_dereference_raw(table->mask_array));
> table_instance_destroy(ti, ufid_ti, false);
> }
>
> @@ -460,17 +518,27 @@ static struct sw_flow *masked_flow_lookup(struct table_instance *ti,
>
> static struct sw_flow *flow_lookup(struct flow_table *tbl,
> struct table_instance *ti,
> + struct mask_array *ma,
> const struct sw_flow_key *key,
> - u32 *n_mask_hit)
> + u32 *n_mask_hit,
> + u32 *index)
> {
> - struct sw_flow_mask *mask;
> struct sw_flow *flow;
> + int i;
>
> - list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
> - flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
> - if (flow) /* Found */
> - return flow;
> + for (i = 0; i < ma->max; i++) {
> + struct sw_flow_mask *mask;
> +
> + mask = rcu_dereference_ovsl(ma->masks[i]);
> + if (mask) {
> + flow = masked_flow_lookup(ti, key, mask, n_mask_hit);
> + if (flow) { /* Found */
> + *index = i;
> + return flow;
> + }
> + }
> }
> +
> return NULL;
> }
>
> @@ -486,6 +554,7 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
> u32 skb_hash,
> u32 *n_mask_hit)
> {
> + struct mask_array *ma = rcu_dereference_ovsl(tbl->mask_array);
> struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
> struct mask_cache_entry *entries, *ce, *del;
> struct sw_flow *flow;
> @@ -493,8 +562,11 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
> int seg;
>
> *n_mask_hit = 0;
> - if (unlikely(!skb_hash))
> - return flow_lookup(tbl, ti, key, n_mask_hit);
> + if (unlikely(!skb_hash)) {
> + u32 __always_unused mask_index;
> +
> + return flow_lookup(tbl, ti, ma, key, n_mask_hit, &mask_index);
> + }
>
> del = NULL;
> entries = this_cpu_ptr(tbl->mask_cache);
> @@ -507,37 +579,33 @@ struct sw_flow *ovs_flow_tbl_lookup_stats(struct flow_table *tbl,
>
> if (ce->skb_hash == skb_hash) {
> struct sw_flow_mask *mask;
> - int i;
> -
> - i = 0;
> - list_for_each_entry_rcu(mask, &tbl->mask_list, list) {
> - if (ce->mask_index == i++) {
> - flow = masked_flow_lookup(ti, key, mask,
> - n_mask_hit);
> - if (flow) /* Found */
> - return flow;
> -
> - break;
> - }
> + struct sw_flow *flow;
> +
> + mask = rcu_dereference_ovsl(ma->masks[ce->mask_index]);
> + if (mask) {
> + flow = masked_flow_lookup(ti, key, mask,
> + n_mask_hit);
> + if (flow) /* Found */
> + return flow;
> }
>
> del = ce;
> break;
> }
>
> - if (!del || (del->skb_hash && !ce->skb_hash)) {
> + if (!del || (del->skb_hash && !ce->skb_hash) ||
> + (rcu_dereference_ovsl(ma->masks[del->mask_index]) &&
> + !rcu_dereference_ovsl(ma->masks[ce->mask_index]))) {
> del = ce;
> }
>
> hash >>= MC_HASH_SHIFT;
> }
>
> - flow = flow_lookup(tbl, ti, key, n_mask_hit);
> + flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, &del->mask_index);
>
> - if (flow) {
> + if (flow)
> del->skb_hash = skb_hash;
> - del->mask_index = (*n_mask_hit - 1);
> - }
>
> return flow;
> }
> @@ -546,26 +614,38 @@ struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *tbl,
> const struct sw_flow_key *key)
> {
> struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
> + struct mask_array *ma = rcu_dereference_ovsl(tbl->mask_array);
> +
> u32 __always_unused n_mask_hit;
> + u32 __always_unused index;
>
> - return flow_lookup(tbl, ti, key, &n_mask_hit);
> + return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &index);
> }
>
> struct sw_flow *ovs_flow_tbl_lookup_exact(struct flow_table *tbl,
> const struct sw_flow_match *match)
> {
> - struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
> - struct sw_flow_mask *mask;
> - struct sw_flow *flow;
> - u32 __always_unused n_mask_hit;
> + struct mask_array *ma = ovsl_dereference(tbl->mask_array);
> + int i;
>
> /* Always called under ovs-mutex. */
> - list_for_each_entry(mask, &tbl->mask_list, list) {
> + for (i = 0; i < ma->max; i++) {
> + struct table_instance *ti = rcu_dereference_ovsl(tbl->ti);
> + u32 __always_unused n_mask_hit;
> + struct sw_flow_mask *mask;
> + struct sw_flow *flow;
> +
> + mask = ovsl_dereference(ma->masks[i]);
> + if (!mask)
> + continue;
> +
> flow = masked_flow_lookup(ti, match->key, mask, &n_mask_hit);
> if (flow && ovs_identifier_is_key(&flow->id) &&
> - ovs_flow_cmp_unmasked_key(flow, match))
> + ovs_flow_cmp_unmasked_key(flow, match)) {
> return flow;
> + }
> }
> +
> return NULL;
> }
>
> @@ -611,13 +691,8 @@ struct sw_flow *ovs_flow_tbl_lookup_ufid(struct flow_table *tbl,
>
> int ovs_flow_tbl_num_masks(const struct flow_table *table)
> {
> - struct sw_flow_mask *mask;
> - int num = 0;
> -
> - list_for_each_entry(mask, &table->mask_list, list)
> - num++;
> -
> - return num;
> + struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);
> + return ma->count;
> }
>
> static struct table_instance *table_instance_expand(struct table_instance *ti,
> @@ -638,8 +713,19 @@ static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
> mask->ref_count--;
>
> if (!mask->ref_count) {
> - list_del_rcu(&mask->list);
> - kfree_rcu(mask, rcu);
> + struct mask_array *ma;
> + int i;
> +
> + ma = ovsl_dereference(tbl->mask_array);
> + for (i = 0; i < ma->max; i++) {
> + if (mask == ovsl_dereference(ma->masks[i])) {
> + RCU_INIT_POINTER(ma->masks[i], NULL);
> + ma->count--;
> + kfree_rcu(mask, rcu);
> + return;
> + }
> + }
> + BUG();
> }
> }
> }
> @@ -689,13 +775,16 @@ static bool mask_equal(const struct sw_flow_mask *a,
> static struct sw_flow_mask *flow_mask_find(const struct flow_table *tbl,
> const struct sw_flow_mask *mask)
> {
> - struct list_head *ml;
> + struct mask_array *ma;
> + int i;
>
> - list_for_each(ml, &tbl->mask_list) {
> - struct sw_flow_mask *m;
> - m = container_of(ml, struct sw_flow_mask, list);
> - if (mask_equal(mask, m))
> - return m;
> + ma = ovsl_dereference(tbl->mask_array);
> + for (i = 0; i < ma->max; i++) {
> + struct sw_flow_mask *t;
> + t = ovsl_dereference(ma->masks[i]);
> +
> + if (t && mask_equal(mask, t))
> + return t;
> }
>
> return NULL;
> @@ -706,15 +795,44 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
> const struct sw_flow_mask *new)
> {
> struct sw_flow_mask *mask;
> +
> mask = flow_mask_find(tbl, new);
> if (!mask) {
> + struct mask_array *ma;
> + int i;
> +
> /* Allocate a new mask if none exsits. */
> mask = mask_alloc();
> if (!mask)
> return -ENOMEM;
> mask->key = new->key;
> mask->range = new->range;
> - list_add_tail_rcu(&mask->list, &tbl->mask_list);
> +
> + /* Add mask to mask-list. */
> + ma = ovsl_dereference(tbl->mask_array);
> + if (ma->count >= ma->max) {
> + int err;
> +
> + err = tbl_mask_array_realloc(tbl, ma->max +
> + MASK_ARRAY_SIZE_MIN);
> + if (err) {
> + kfree(mask);
> + return err;
> + }
> +
> + ma = ovsl_dereference(tbl->mask_array);
> + }
> +
> + for (i = 0; i < ma->max; i++) {
> + const struct sw_flow_mask *t;
> +
> + t = ovsl_dereference(ma->masks[i]);
> + if (!t) {
> + rcu_assign_pointer(ma->masks[i], mask);
> + ma->count++;
> + break;
> + }
> + }
> } else {
> BUG_ON(!mask->ref_count);
> mask->ref_count++;
> diff --git a/net/openvswitch/flow_table.h b/net/openvswitch/flow_table.h
> index 04b6b1c..8a5cea6 100644
> --- a/net/openvswitch/flow_table.h
> +++ b/net/openvswitch/flow_table.h
> @@ -27,6 +27,12 @@ struct mask_cache_entry {
> u32 mask_index;
> };
>
> +struct mask_array {
> + struct rcu_head rcu;
> + int count, max;
> + struct sw_flow_mask __rcu *masks[];
> +};
> +
> struct table_instance {
> struct hlist_head *buckets;
> unsigned int n_buckets;
> @@ -40,7 +46,7 @@ struct flow_table {
> struct table_instance __rcu *ti;
> struct table_instance __rcu *ufid_ti;
> struct mask_cache_entry __percpu *mask_cache;
> - struct list_head mask_list;
> + struct mask_array __rcu *mask_array;
> unsigned long last_rehash;
> unsigned int count;
> unsigned int ufid_count;
> --
> 1.8.3.1
>
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