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dpif-netdev: Store miniflow length in exact match cache

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This optimization is done to avoid calling count_1bits(), which, if
the popcnt istruction is not available might is slow. popcnt may not
be available because:

- We are running on old hardware
- (more likely) We're using a generic build (i.e. packaged OVS from a
  distro), not tuned for the specific CPU

Signed-off-by: Daniele Di Proietto <ddiproietto@vmware.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
This commit is contained in:
Daniele Di Proietto
2014-09-06 08:10:43 +00:00
committed by Jarno Rajahalme
parent 79df317f0b
commit 0023a1cb45
1 changed files with 14 additions and 8 deletions
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22
lib/dpif-netdev.c
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@@ -130,6 +130,7 @@ struct netdev_flow_key {
struct emc_entry {
uint32_t hash;
uint32_t mf_len;
struct netdev_flow_key mf;
struct dp_netdev_flow *flow;
};
@@ -410,6 +411,7 @@ emc_cache_init(struct emc_cache *flow_cache)
for (i = 0; i < ARRAY_SIZE(flow_cache->entries); i++) {
flow_cache->entries[i].flow = NULL;
flow_cache->entries[i].hash = 0;
flow_cache->entries[i].mf_len = 0;
miniflow_initialize(&flow_cache->entries[i].mf.flow,
flow_cache->entries[i].mf.buf);
}
@@ -1248,11 +1250,10 @@ netdev_flow_key_size(uint32_t flow_u32s)
/* Used to compare 'netdev_flow_key's (miniflows) in the exact match cache. */
static inline bool
netdev_flow_key_equal(const struct netdev_flow_key *a,
const struct netdev_flow_key *b)
const struct netdev_flow_key *b,
uint32_t size)
{
uint32_t size = count_1bits(a->flow.map);
return !memcmp(a, b, netdev_flow_key_size(size));
return !memcmp(a, b, size);
}
static inline void
@@ -1260,7 +1261,7 @@ netdev_flow_key_clone(struct netdev_flow_key *dst,
const struct netdev_flow_key *src,
uint32_t size)
{
memcpy(dst, src, netdev_flow_key_size(size));
memcpy(dst, src, size);
}
static inline bool
@@ -1294,8 +1295,11 @@ emc_change_entry(struct emc_entry *ce, struct dp_netdev_flow *flow,
}
}
if (mf) {
netdev_flow_key_clone(&ce->mf, mf, count_1bits(mf->flow.map));
uint32_t mf_len = netdev_flow_key_size(count_1bits(mf->flow.map));
netdev_flow_key_clone(&ce->mf, mf, mf_len);
ce->hash = hash;
ce->mf_len = mf_len;
}
}
@@ -1309,7 +1313,8 @@ emc_insert(struct emc_cache *cache, const struct miniflow *mf, uint32_t hash,
EMC_FOR_EACH_POS_WITH_HASH(cache, current_entry, hash) {
if (current_entry->hash == hash
&& netdev_flow_key_equal(&current_entry->mf,
miniflow_to_netdev_flow_key(mf))) {
miniflow_to_netdev_flow_key(mf),
current_entry->mf_len)) {
/* We found the entry with the 'mf' miniflow */
emc_change_entry(current_entry, flow, NULL, 0);
@@ -1340,7 +1345,8 @@ emc_lookup(struct emc_cache *cache, const struct miniflow *mf, uint32_t hash)
EMC_FOR_EACH_POS_WITH_HASH(cache, current_entry, hash) {
if (current_entry->hash == hash && emc_entry_alive(current_entry)
&& netdev_flow_key_equal(&current_entry->mf,
miniflow_to_netdev_flow_key(mf))) {
miniflow_to_netdev_flow_key(mf),
current_entry->mf_len)) {
/* We found the entry with the 'mf' miniflow */
return current_entry->flow;