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/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2015 Nicira, Inc.
* Copyright (c) 2019, 2020, 2021 Intel Corporation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef DPIF_NETDEV_PRIVATE_DFC_H
#define DPIF_NETDEV_PRIVATE_DFC_H 1
#include "dpif.h"
#include "dpif-netdev-private-dpcls.h"
#include "dpif-netdev-private-flow.h"
#include <stdbool.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/* EMC cache and SMC cache compose the datapath flow cache (DFC)
*
* Exact match cache for frequently used flows
*
* The cache uses a 32-bit hash of the packet (which can be the RSS hash) to
* search its entries for a miniflow that matches exactly the miniflow of the
* packet. It stores the 'dpcls_rule' (rule) that matches the miniflow.
*
* A cache entry holds a reference to its 'dp_netdev_flow'.
*
* A miniflow with a given hash can be in one of EM_FLOW_HASH_SEGS different
* entries. The 32-bit hash is split into EM_FLOW_HASH_SEGS values (each of
* them is EM_FLOW_HASH_SHIFT bits wide and the remainder is thrown away). Each
* value is the index of a cache entry where the miniflow could be.
*
*
* Signature match cache (SMC)
*
* This cache stores a 16-bit signature for each flow without storing keys, and
* stores the corresponding 16-bit flow_table index to the 'dp_netdev_flow'.
* Each flow thus occupies 32bit which is much more memory efficient than EMC.
* SMC uses a set-associative design that each bucket contains
* SMC_ENTRY_PER_BUCKET number of entries.
* Since 16-bit flow_table index is used, if there are more than 2^16
* dp_netdev_flow, SMC will miss them that cannot be indexed by a 16-bit value.
*
*
* Thread-safety
* =============
*
* Each pmd_thread has its own private exact match cache and signature match
* cache.
* If dp_netdev_input is not called from a pmd thread, a mutex is used.
*/
#define EM_FLOW_HASH_SHIFT 13
#define EM_FLOW_HASH_ENTRIES (1u << EM_FLOW_HASH_SHIFT)
#define EM_FLOW_HASH_MASK (EM_FLOW_HASH_ENTRIES - 1)
#define EM_FLOW_HASH_SEGS 2
/* SMC uses a set-associative design. A bucket contains a set of entries that
* a flow item can occupy. For now, it uses one hash function rather than two
* as for the EMC design. */
#define SMC_ENTRY_PER_BUCKET 4
#define SMC_ENTRIES (1u << 20)
#define SMC_BUCKET_CNT (SMC_ENTRIES / SMC_ENTRY_PER_BUCKET)
#define SMC_MASK (SMC_BUCKET_CNT - 1)
/* Default EMC insert probability is 1 / DEFAULT_EM_FLOW_INSERT_INV_PROB */
#define DEFAULT_EM_FLOW_INSERT_INV_PROB 100
#define DEFAULT_EM_FLOW_INSERT_MIN (UINT32_MAX / \
DEFAULT_EM_FLOW_INSERT_INV_PROB)
/* Forward declaration for SMC function prototype that requires access to
* 'struct dp_netdev_pmd_thread'. */
struct dp_netdev_pmd_thread;
/* Forward declaration for EMC and SMC batch insert function prototypes that
* require access to 'struct dpcls_rule'. */
struct dpcls_rule;
struct emc_entry {
struct dp_netdev_flow *flow;
struct netdev_flow_key key; /* key.hash used for emc hash value. */
};
struct emc_cache {
struct emc_entry entries[EM_FLOW_HASH_ENTRIES];
int sweep_idx; /* For emc_cache_slow_sweep(). */
};
struct smc_bucket {
uint16_t sig[SMC_ENTRY_PER_BUCKET];
uint16_t flow_idx[SMC_ENTRY_PER_BUCKET];
};
/* Signature match cache, differentiate from EMC cache */
struct smc_cache {
struct smc_bucket buckets[SMC_BUCKET_CNT];
};
struct dfc_cache {
struct emc_cache emc_cache;
struct smc_cache smc_cache;
};
/* Iterate in the exact match cache through every entry that might contain a
* miniflow with hash 'HASH'. */
#define EMC_FOR_EACH_POS_WITH_HASH(EMC, CURRENT_ENTRY, HASH) \
for (uint32_t i__ = 0, srch_hash__ = (HASH); \
(CURRENT_ENTRY) = &(EMC)->entries[srch_hash__ & EM_FLOW_HASH_MASK], \
i__ < EM_FLOW_HASH_SEGS; \
i__++, srch_hash__ >>= EM_FLOW_HASH_SHIFT)
void dfc_cache_init(struct dfc_cache *flow_cache);
void dfc_cache_uninit(struct dfc_cache *flow_cache);
/* Check and clear dead flow references slowly (one entry at each
* invocation). */
void emc_cache_slow_sweep(struct emc_cache *flow_cache);
static inline bool
emc_entry_alive(struct emc_entry *ce)
{
return ce->flow && !ce->flow->dead;
}
/* Used to compare 'netdev_flow_key' in the exact match cache to a miniflow.
* The maps are compared bitwise, so both 'key->mf' and 'mf' must have been
* generated by miniflow_extract. */
static inline bool
emc_flow_key_equal_mf(const struct netdev_flow_key *key,
const struct miniflow *mf)
{
return !memcmp(&key->mf, mf, key->len);
}
static inline struct dp_netdev_flow *
emc_lookup(struct emc_cache *cache, const struct netdev_flow_key *key)
{
struct emc_entry *current_entry;
EMC_FOR_EACH_POS_WITH_HASH (cache, current_entry, key->hash) {
if (current_entry->key.hash == key->hash
&& emc_entry_alive(current_entry)
&& emc_flow_key_equal_mf(¤t_entry->key, &key->mf)) {
/* We found the entry with the 'key->mf' miniflow */
return current_entry->flow;
}
}
return NULL;
}
/* Insert a batch of keys/flows into the EMC and SMC caches. */
void
emc_probabilistic_insert_batch(struct dp_netdev_pmd_thread *pmd,
const struct netdev_flow_key *keys,
struct dpcls_rule **rules,
uint32_t emc_insert_mask);
void
smc_insert_batch(struct dp_netdev_pmd_thread *pmd,
const struct netdev_flow_key *keys,
struct dpcls_rule **rules,
uint32_t smc_insert_mask);
struct dp_netdev_flow *
smc_lookup_single(struct dp_netdev_pmd_thread *pmd,
struct dp_packet *packet,
struct netdev_flow_key *key);
#ifdef __cplusplus
}
#endif
#endif /* dpif-netdev-private-dfc.h */
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