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Introduce sparse flows and masks, to reduce memory usage and improve speed.

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A cls_rule is 324 bytes on i386 now.  The cost of a flow table lookup is
currently proportional to this size, which is going to continue to grow.
However, the required cost of a flow table lookup, with the classifier that
we currently use, is only proportional to the number of bits that a rule
actually matches.  This commit implements that optimization by replacing
the match inside "struct cls_rule" by a sparse representation.

This reduces struct cls_rule to 100 bytes on i386.

There is still some headroom for further optimization following this
commit:

    - I suspect that adding an 'n' member to struct miniflow would make
      miniflow operations faster, since popcount() has some cost.

    - It's probably possible to replace the "struct minimatch" in cls_rule
      by just a "struct miniflow", since the cls_rule's cls_table has a
      copy of the minimask.

    - Some of the miniflow operations aren't well-optimized.

Signed-off-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Ben Pfaff
2012-09-04 12:43:53 -07:00
parent 9879b94f43
commit 5cb7a79840
13 changed files with 1088 additions and 129 deletions
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114
lib/classifier.c
View File

@@ -28,16 +28,16 @@
#include "packets.h"
static struct cls_table *find_table(const struct classifier *,
const struct flow_wildcards *);
const struct minimask *);
static struct cls_table *insert_table(struct classifier *,
const struct flow_wildcards *);
const struct minimask *);
static void destroy_table(struct classifier *, struct cls_table *);
static struct cls_rule *find_match(const struct cls_table *,
const struct flow *);
static struct cls_rule *find_equal(struct cls_table *, const struct flow *,
uint32_t hash);
static struct cls_rule *find_equal(struct cls_table *,
const struct miniflow *, uint32_t hash);
static struct cls_rule *insert_rule(struct cls_table *, struct cls_rule *);
/* Iterates RULE over HEAD and all of the cls_rules on HEAD->list. */
@@ -54,20 +54,28 @@ static struct cls_rule *next_rule_in_list(struct cls_rule *);
/* cls_rule. */
/* Initializes 'rule' to match packets specified by 'match' at the given
* 'priority'.
* 'priority'. 'match' must satisfy the invariant described in the comment at
* the definition of struct match.
*
* The caller must eventually destroy 'rule' with cls_rule_destroy().
*
* 'match' must satisfy the invariant described in the comment at the
* definition of struct match.
*
* (OpenFlow uses priorities between 0 and UINT16_MAX, inclusive, but
* internally Open vSwitch supports a wider range.) */
void
cls_rule_init(struct cls_rule *rule,
const struct match *match, unsigned int priority)
{
rule->match = *match;
minimatch_init(&rule->match, match);
rule->priority = priority;
}
/* Same as cls_rule_init() for initialization from a "struct minimatch". */
void
cls_rule_init_from_minimatch(struct cls_rule *rule,
const struct minimatch *match,
unsigned int priority)
{
minimatch_clone(&rule->match, match);
rule->priority = priority;
}
@@ -77,7 +85,8 @@ cls_rule_init(struct cls_rule *rule,
void
cls_rule_clone(struct cls_rule *dst, const struct cls_rule *src)
{
*dst = *src;
minimatch_clone(&dst->match, &src->match);
dst->priority = src->priority;
}
/* Frees memory referenced by 'rule'. Doesn't free 'rule' itself (it's
@@ -85,9 +94,9 @@ cls_rule_clone(struct cls_rule *dst, const struct cls_rule *src)
*
* ('rule' must not currently be in a classifier.) */
void
cls_rule_destroy(struct cls_rule *rule OVS_UNUSED)
cls_rule_destroy(struct cls_rule *rule)
{
/* Nothing to do yet. */
minimatch_destroy(&rule->match);
}
/* Returns true if 'a' and 'b' match the same packets at the same priority,
@@ -95,28 +104,28 @@ cls_rule_destroy(struct cls_rule *rule OVS_UNUSED)
bool
cls_rule_equal(const struct cls_rule *a, const struct cls_rule *b)
{
return a->priority == b->priority && match_equal(&a->match, &b->match);
return a->priority == b->priority && minimatch_equal(&a->match, &b->match);
}
/* Returns a hash value for 'rule', folding in 'basis'. */
uint32_t
cls_rule_hash(const struct cls_rule *rule, uint32_t basis)
{
return match_hash(&rule->match, hash_int(rule->priority, basis));
return minimatch_hash(&rule->match, hash_int(rule->priority, basis));
}
/* Appends a string describing 'rule' to 's'. */
void
cls_rule_format(const struct cls_rule *rule, struct ds *s)
{
match_format(&rule->match, s, rule->priority);
minimatch_format(&rule->match, s, rule->priority);
}
/* Returns true if 'rule' matches every packet, false otherwise. */
bool
cls_rule_is_catchall(const struct cls_rule *rule)
{
return flow_wildcards_is_catchall(&rule->match.wc);
return minimask_is_catchall(&rule->match.mask);
}
/* Initializes 'cls' as a classifier that initially contains no classification
@@ -178,9 +187,9 @@ classifier_replace(struct classifier *cls, struct cls_rule *rule)
struct cls_rule *old_rule;
struct cls_table *table;
table = find_table(cls, &rule->match.wc);
table = find_table(cls, &rule->match.mask);
if (!table) {
table = insert_table(cls, &rule->match.wc);
table = insert_table(cls, &rule->match.mask);
}
old_rule = insert_rule(table, rule);
@@ -213,7 +222,7 @@ classifier_remove(struct classifier *cls, struct cls_rule *rule)
struct cls_rule *head;
struct cls_table *table;
table = find_table(cls, &rule->match.wc);
table = find_table(cls, &rule->match.mask);
head = find_equal(table, &rule->match.flow, rule->hmap_node.hash);
if (head != rule) {
list_remove(&rule->list);
@@ -263,13 +272,14 @@ classifier_find_rule_exactly(const struct classifier *cls,
struct cls_rule *head, *rule;
struct cls_table *table;
table = find_table(cls, &target->match.wc);
table = find_table(cls, &target->match.mask);
if (!table) {
return NULL;
}
head = find_equal(table, &target->match.flow,
flow_hash(&target->match.flow, 0));
miniflow_hash_in_minimask(&target->match.flow,
&target->match.mask, 0));
FOR_EACH_RULE_IN_LIST (rule, head) {
if (target->priority >= rule->priority) {
return target->priority == rule->priority ? rule : NULL;
@@ -306,17 +316,18 @@ classifier_rule_overlaps(const struct classifier *cls,
struct cls_table *table;
HMAP_FOR_EACH (table, hmap_node, &cls->tables) {
struct flow_wildcards wc;
uint32_t storage[FLOW_U32S];
struct minimask mask;
struct cls_rule *head;
flow_wildcards_combine(&wc, &target->match.wc, &table->wc);
minimask_combine(&mask, &target->match.mask, &table->mask, storage);
HMAP_FOR_EACH (head, hmap_node, &table->rules) {
struct cls_rule *rule;
FOR_EACH_RULE_IN_LIST (rule, head) {
if (rule->priority == target->priority
&& flow_equal_except(&target->match.flow,
&rule->match.flow, &wc)) {
&& miniflow_equal_in_minimask(&target->match.flow,
&rule->match.flow, &mask)) {
return true;
}
}
@@ -361,11 +372,11 @@ classifier_rule_overlaps(const struct classifier *cls,
* Ignores rule->priority. */
bool
cls_rule_is_loose_match(const struct cls_rule *rule,
const struct match *criteria)
const struct minimatch *criteria)
{
return (!flow_wildcards_has_extra(&rule->match.wc, &criteria->wc)
&& flow_equal_except(&rule->match.flow, &criteria->flow,
&criteria->wc));
return (!minimask_has_extra(&rule->match.mask, &criteria->mask)
&& miniflow_equal_in_minimask(&rule->match.flow, &criteria->flow,
&criteria->mask));
}
/* Iteration. */
@@ -374,14 +385,15 @@ static bool
rule_matches(const struct cls_rule *rule, const struct cls_rule *target)
{
return (!target
|| flow_equal_except(&rule->match.flow, &target->match.flow,
&target->match.wc));
|| miniflow_equal_in_minimask(&rule->match.flow,
&target->match.flow,
&target->match.mask));
}
static struct cls_rule *
search_table(const struct cls_table *table, const struct cls_rule *target)
{
if (!target || !flow_wildcards_has_extra(&table->wc, &target->match.wc)) {
if (!target || !minimask_has_extra(&table->mask, &target->match.mask)) {
struct cls_rule *rule;
HMAP_FOR_EACH (rule, hmap_node, &table->rules) {
@@ -463,13 +475,13 @@ cls_cursor_next(struct cls_cursor *cursor, struct cls_rule *rule)
}
static struct cls_table *
find_table(const struct classifier *cls, const struct flow_wildcards *wc)
find_table(const struct classifier *cls, const struct minimask *mask)
{
struct cls_table *table;
HMAP_FOR_EACH_IN_BUCKET (table, hmap_node, flow_wildcards_hash(wc, 0),
HMAP_FOR_EACH_IN_BUCKET (table, hmap_node, minimask_hash(mask, 0),
&cls->tables) {
if (flow_wildcards_equal(wc, &table->wc)) {
if (minimask_equal(mask, &table->mask)) {
return table;
}
}
@@ -477,15 +489,14 @@ find_table(const struct classifier *cls, const struct flow_wildcards *wc)
}
static struct cls_table *
insert_table(struct classifier *cls, const struct flow_wildcards *wc)
insert_table(struct classifier *cls, const struct minimask *mask)
{
struct cls_table *table;
table = xzalloc(sizeof *table);
hmap_init(&table->rules);
table->wc = *wc;
table->is_catchall = flow_wildcards_is_catchall(&table->wc);
hmap_insert(&cls->tables, &table->hmap_node, flow_wildcards_hash(wc, 0));
minimask_clone(&table->mask, mask);
hmap_insert(&cls->tables, &table->hmap_node, minimask_hash(mask, 0));
return table;
}
@@ -493,6 +504,7 @@ insert_table(struct classifier *cls, const struct flow_wildcards *wc)
static void
destroy_table(struct classifier *cls, struct cls_table *table)
{
minimask_destroy(&table->mask);
hmap_remove(&cls->tables, &table->hmap_node);
hmap_destroy(&table->rules);
free(table);
@@ -501,35 +513,26 @@ destroy_table(struct classifier *cls, struct cls_table *table)
static struct cls_rule *
find_match(const struct cls_table *table, const struct flow *flow)
{
uint32_t hash = flow_hash_in_minimask(flow, &table->mask, 0);
struct cls_rule *rule;
if (table->is_catchall) {
HMAP_FOR_EACH (rule, hmap_node, &table->rules) {
HMAP_FOR_EACH_WITH_HASH (rule, hmap_node, hash, &table->rules) {
if (miniflow_equal_flow_in_minimask(&rule->match.flow, flow,
&table->mask)) {
return rule;
}
} else {
struct flow f;
f = *flow;
flow_zero_wildcards(&f, &table->wc);
HMAP_FOR_EACH_WITH_HASH (rule, hmap_node, flow_hash(&f, 0),
&table->rules) {
if (flow_equal(&f, &rule->match.flow)) {
return rule;
}
}
}
return NULL;
}
static struct cls_rule *
find_equal(struct cls_table *table, const struct flow *flow, uint32_t hash)
find_equal(struct cls_table *table, const struct miniflow *flow, uint32_t hash)
{
struct cls_rule *head;
HMAP_FOR_EACH_WITH_HASH (head, hmap_node, hash, &table->rules) {
if (flow_equal(&head->match.flow, flow)) {
if (miniflow_equal(&head->match.flow, flow)) {
return head;
}
}
@@ -541,7 +544,8 @@ insert_rule(struct cls_table *table, struct cls_rule *new)
{
struct cls_rule *head;
new->hmap_node.hash = flow_hash(&new->match.flow, 0);
new->hmap_node.hash = miniflow_hash_in_minimask(&new->match.flow,
&new->match.mask, 0);
head = find_equal(table, &new->match.flow, new->hmap_node.hash);
if (!head) {