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datapath: Convert mask list in mask array.
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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.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@redhat.com>
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Pravin B Shelar committed Apr 29, 2014
1 parent 5604935 commit d49fc3f
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Showing 3 changed files with 163 additions and 46 deletions.
1 change: 0 additions & 1 deletion datapath/flow.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -127,7 +127,6 @@ 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;
};
Expand Down
200 changes: 156 additions & 44 deletions datapath/flow_table.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,7 @@
#include "vlan.h"

#define TBL_MIN_BUCKETS 1024
#define MASK_ARRAY_SIZE_MIN 16
#define REHASH_INTERVAL (10 * 60 * HZ)

#define MC_HASH_SHIFT 8
Expand Down Expand Up @@ -211,26 +212,83 @@ 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;

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 (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);

return 0;
}

int ovs_flow_tbl_init(struct flow_table *table)
{
struct table_instance *ti;
struct mask_array *ma;

table->mask_cache = __alloc_percpu(sizeof(struct mask_cache_entry) *
MC_HASH_ENTRIES, __alignof__(struct mask_cache_entry));
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) {
free_percpu(table->mask_cache);
return -ENOMEM;
}
if (!ti)
goto free_mask_array;

rcu_assign_pointer(table->ti, ti);
INIT_LIST_HEAD(&table->mask_list);
rcu_assign_pointer(table->mask_array, ma);
table->last_rehash = jiffies;
table->count = 0;
return 0;

free_mask_array:
kfree((struct mask_array __force *)table->mask_array);
free_mask_cache:
free_percpu(table->mask_cache);
return -ENOMEM;
}

static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
Expand Down Expand Up @@ -276,6 +334,7 @@ void ovs_flow_tbl_destroy(struct flow_table *table)
struct table_instance *ti = (struct table_instance __force *)table->ti;

free_percpu(table->mask_cache);
kfree((struct mask_array __force *)table->mask_array);
table_instance_destroy(ti, false);
}

Expand Down Expand Up @@ -457,17 +516,27 @@ 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;
}

Expand All @@ -483,15 +552,19 @@ 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;
u32 hash = skb_hash;
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);
Expand All @@ -504,58 +577,54 @@ 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;
struct sw_flow *flow;

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;
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;

break;
}
}
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);

if (flow) {
flow = flow_lookup(tbl, ti, ma, key, n_mask_hit, &del->mask_index);
if (flow)
del->skb_hash = skb_hash;
del->mask_index = (*n_mask_hit - 1);
}

return flow;
}

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;

n_mask_hit = 0;
return flow_lookup(tbl, ti, key, &n_mask_hit);
return flow_lookup(tbl, ti, ma, key, &n_mask_hit, &index);
}

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++;
struct mask_array *ma;

return num;
ma = rcu_dereference_ovsl(table->mask_array);
return ma->count;
}

static struct table_instance *table_instance_expand(struct table_instance *ti)
Expand All @@ -575,7 +644,19 @@ 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);
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--;
goto free;
}
}
BUG();
free:
call_rcu(&mask->rcu, rcu_free_sw_flow_mask_cb);
}
}
Expand Down Expand Up @@ -620,13 +701,16 @@ 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;

ma = ovsl_dereference(tbl->mask_array);
for (i = 0; i < ma->max; i++) {
struct sw_flow_mask *t;

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;
t = ovsl_dereference(ma->masks[i]);
if (t && mask_equal(mask, t))
return t;
}

return NULL;
Expand All @@ -637,15 +721,43 @@ static int flow_mask_insert(struct flow_table *tbl, struct sw_flow *flow,
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++;
Expand Down
8 changes: 7 additions & 1 deletion datapath/flow_table.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,12 @@ 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 flex_array *buckets;
unsigned int n_buckets;
Expand All @@ -53,7 +59,7 @@ struct table_instance {
struct flow_table {
struct table_instance __rcu *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;
};
Expand Down

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