Acked-by: Billy O'Mahony <[email protected]>
> -----Original Message-----
> From: Wang, Yipeng1
> Sent: Tuesday, July 10, 2018 11:14 AM
> To: [email protected]; [email protected]; O Mahony, Billy
> <[email protected]>
> Cc: Wang, Yipeng1 <[email protected]>; Stokes, Ian
> <[email protected]>; [email protected]
> Subject: [PATCH v5 1/2] dpif-netdev: Add SMC cache after EMC cache
>
> This patch adds a signature match cache (SMC) after exact match cache (EMC).
> The difference between SMC and EMC is SMC only stores a signature of a flow
> thus it is much more memory efficient. With same memory space, EMC can
> store 8k flows while SMC can store 1M flows. It is generally beneficial to
> turn on
> SMC but turn off EMC when traffic flow count is much larger than EMC size.
>
> SMC cache will map a signature to an dp_netdev_flow index in flow_table. Thus,
> we add two new APIs in cmap for lookup key by index and lookup index by key.
>
> For now, SMC is an experimental feature that it is turned off by default. One
> can
> turn it on using ovsdb options.
>
> Signed-off-by: Yipeng Wang <[email protected]>
> Co-authored-by: Jan Scheurich <[email protected]>
> Signed-off-by: Jan Scheurich <[email protected]>
> ---
> Documentation/topics/dpdk/bridge.rst | 15 ++
> NEWS | 2 +
> lib/cmap.c | 74 ++++++++
> lib/cmap.h | 11 ++
> lib/dpif-netdev-perf.h | 1 +
> lib/dpif-netdev.c | 329
> +++++++++++++++++++++++++++++++----
> tests/pmd.at | 1 +
> vswitchd/vswitch.xml | 13 ++
> 8 files changed, 409 insertions(+), 37 deletions(-)
>
> diff --git a/Documentation/topics/dpdk/bridge.rst
> b/Documentation/topics/dpdk/bridge.rst
> index 63f8a62..df74c02 100644
> --- a/Documentation/topics/dpdk/bridge.rst
> +++ b/Documentation/topics/dpdk/bridge.rst
> @@ -102,3 +102,18 @@ For certain traffic profiles with many parallel flows,
> it's
> recommended to set ``N`` to '0' to achieve higher forwarding performance.
>
> For more information on the EMC refer to :doc:`/intro/install/dpdk` .
> +
> +
> +SMC cache (experimental)
> +-------------------------
> +
> +SMC cache or signature match cache is a new cache level after EMC cache.
> +The difference between SMC and EMC is SMC only stores a signature of a
> +flow thus it is much more memory efficient. With same memory space, EMC
> +can store 8k flows while SMC can store 1M flows. When traffic flow
> +count is much larger than EMC size, it is generally beneficial to turn
> +off EMC and turn on SMC. It is currently turned off by default and an
> experimental feature.
> +
> +To turn on SMC::
> +
> + $ ovs-vsctl --no-wait set Open_vSwitch .
> + other_config:smc-enable=true
> diff --git a/NEWS b/NEWS
> index 92e9b92..f30a1e0 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -44,6 +44,8 @@ Post-v2.9.0
> ovs-appctl dpif-netdev/pmd-perf-show
> * Supervision of PMD performance metrics and logging of suspicious
> iterations
> + * Add signature match cache (SMC) as experimental feature. When turned
> on,
> + it improves throughput when traffic has many more flows than EMC size.
> - ERSPAN:
> * Implemented ERSPAN protocol (draft-foschiano-erspan-00.txt) for
> both kernel datapath and userspace datapath.
> diff --git a/lib/cmap.c b/lib/cmap.c
> index 07719a8..cb9cd32 100644
> --- a/lib/cmap.c
> +++ b/lib/cmap.c
> @@ -373,6 +373,80 @@ cmap_find(const struct cmap *cmap, uint32_t hash)
> hash);
> }
>
> +/* Find a node by the index of the entry of cmap. Index N means the
> +N/CMAP_K
> + * bucket and N%CMAP_K entry in that bucket.
> + * Notice that it is not protected by the optimistic lock (versioning)
> +because
> + * it does not compare the hashes. Currently it is only used by the
> +datapath
> + * SMC cache.
> + *
> + * Return node for the entry of index or NULL if the index beyond
> +boundary */ const struct cmap_node * cmap_find_by_index(const struct
> +cmap *cmap, uint32_t index) {
> + const struct cmap_impl *impl = cmap_get_impl(cmap);
> +
> + uint32_t b = index / CMAP_K;
> + uint32_t e = index % CMAP_K;
> +
> + if (b > impl->mask) {
> + return NULL;
> + }
> +
> + const struct cmap_bucket *bucket = &impl->buckets[b];
> +
> + return cmap_node_next(&bucket->nodes[e]);
> +}
> +
> +/* Find the index of certain hash value. Currently only used by the
> +datapath
> + * SMC cache.
> + *
> + * Return the index of the entry if found, or UINT32_MAX if not found.
> +The
> + * function assumes entry index cannot be larger than UINT32_MAX. */
> +uint32_t cmap_find_index(const struct cmap *cmap, uint32_t hash) {
> + const struct cmap_impl *impl = cmap_get_impl(cmap);
> + uint32_t h1 = rehash(impl, hash);
> + uint32_t h2 = other_hash(h1);
> +
> + uint32_t b_index1 = h1 & impl->mask;
> + uint32_t b_index2 = h2 & impl->mask;
> +
> + uint32_t c1, c2;
> + uint32_t index = UINT32_MAX;
> +
> + const struct cmap_bucket *b1 = &impl->buckets[b_index1];
> + const struct cmap_bucket *b2 = &impl->buckets[b_index2];
> +
> + do {
> + do {
> + c1 = read_even_counter(b1);
> + for (int i = 0; i < CMAP_K; i++) {
> + if (b1->hashes[i] == hash) {
> + index = b_index1 * CMAP_K + i;
> + }
> + }
> + } while (OVS_UNLIKELY(counter_changed(b1, c1)));
> + if (index != UINT32_MAX) {
> + break;
> + }
> + do {
> + c2 = read_even_counter(b2);
> + for (int i = 0; i < CMAP_K; i++) {
> + if (b2->hashes[i] == hash) {
> + index = b_index2 * CMAP_K + i;
> + }
> + }
> + } while (OVS_UNLIKELY(counter_changed(b2, c2)));
> +
> + if (index != UINT32_MAX) {
> + break;
> + }
> + } while (OVS_UNLIKELY(counter_changed(b1, c1)));
> +
> + return index;
> +}
> +
> /* Looks up multiple 'hashes', when the corresponding bit in 'map' is 1,
> * and sets the corresponding pointer in 'nodes', if the hash value was
> * found from the 'cmap'. In other cases the 'nodes' values are not changed,
> diff --git a/lib/cmap.h b/lib/cmap.h index 8bfb6c0..d9db3c9 100644
> --- a/lib/cmap.h
> +++ b/lib/cmap.h
> @@ -145,6 +145,17 @@ size_t cmap_replace(struct cmap *, struct cmap_node
> *old_node, const struct cmap_node *cmap_find(const struct cmap *, uint32_t
> hash); struct cmap_node *cmap_find_protected(const struct cmap *, uint32_t
> hash);
>
> +/* Find node by index or find index by hash. The 'index' of a cmap
> +entry is a
> + * way to combine the specific bucket and the entry of the bucket into
> +a
> + * convenient single integer value. In other words, it is the index of
> +the
> + * entry and each entry has an unique index. It is not used internally
> +by
> + * cmap.
> + * Currently the functions assume index will not be larger than
> +uint32_t. In
> + * OvS table size is usually much smaller than this size.*/ const
> +struct cmap_node * cmap_find_by_index(const struct cmap *,
> + uint32_t index); uint32_t
> +cmap_find_index(const struct cmap *, uint32_t hash);
> +
> /* Looks up multiple 'hashes', when the corresponding bit in 'map' is 1,
> * and sets the corresponding pointer in 'nodes', if the hash value was
> * found from the 'cmap'. In other cases the 'nodes' values are not changed,
> diff --git a/lib/dpif-netdev-perf.h b/lib/dpif-netdev-perf.h index
> b8aa4e3..299d52a 100644
> --- a/lib/dpif-netdev-perf.h
> +++ b/lib/dpif-netdev-perf.h
> @@ -56,6 +56,7 @@ extern "C" {
>
> enum pmd_stat_type {
> PMD_STAT_EXACT_HIT, /* Packets that had an exact match (emc). */
> + PMD_STAT_SMC_HIT, /* Packets that had a sig match hit (SMC). */
> PMD_STAT_MASKED_HIT, /* Packets that matched in the flow table. */
> PMD_STAT_MISS, /* Packets that did not match and upcall was ok.
> */
> PMD_STAT_LOST, /* Packets that did not match and upcall failed.
> */
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 8b3556d..13a20f0
> 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -130,7 +130,9 @@ struct netdev_flow_key {
> uint64_t buf[FLOW_MAX_PACKET_U64S]; };
>
> -/* Exact match cache for frequently used flows
> +/* 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 @@
> -144,6 +146,17 @@ struct netdev_flow_key {
> * 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
> * =============
> *
> @@ -156,6 +169,14 @@ struct netdev_flow_key { #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 / \
> @@ -171,6 +192,21 @@ struct emc_cache {
> 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)
> \
> @@ -215,10 +251,11 @@ static void dpcls_insert(struct dpcls *, struct
> dpcls_rule *,
> const struct netdev_flow_key *mask); static void
> dpcls_remove(struct dpcls *, struct dpcls_rule *); static bool
> dpcls_lookup(struct
> dpcls *cls,
> - const struct netdev_flow_key keys[],
> + const struct netdev_flow_key *keys[],
> struct dpcls_rule **rules, size_t cnt,
> int *num_lookups_p);
> -
> +static bool dpcls_rule_matches_key(const struct dpcls_rule *rule,
> + const struct netdev_flow_key *target);
> /* Set of supported meter flags */
> #define DP_SUPPORTED_METER_FLAGS_MASK \
> (OFPMF13_STATS | OFPMF13_PKTPS | OFPMF13_KBPS | OFPMF13_BURST)
> @@ -285,6 +322,8 @@ struct dp_netdev {
> OVS_ALIGNED_VAR(CACHE_LINE_SIZE) atomic_uint32_t emc_insert_min;
> /* Enable collection of PMD performance metrics. */
> atomic_bool pmd_perf_metrics;
> + /* Enable the SMC cache from ovsdb config */
> + atomic_bool smc_enable_db;
>
> /* Protects access to ofproto-dpif-upcall interface during revalidator
> * thread synchronization. */
> @@ -587,7 +626,7 @@ struct dp_netdev_pmd_thread {
> * NON_PMD_CORE_ID can be accessed by multiple threads, and thusly
> * need to be protected by 'non_pmd_mutex'. Every other instance
> * will only be accessed by its own pmd thread. */
> - struct emc_cache flow_cache;
> + OVS_ALIGNED_VAR(CACHE_LINE_SIZE) struct dfc_cache flow_cache;
>
> /* Flow-Table and classifiers
> *
> @@ -755,6 +794,7 @@ static int dpif_netdev_xps_get_tx_qid(const struct
> dp_netdev_pmd_thread *pmd,
>
> static inline bool emc_entry_alive(struct emc_entry *ce); static void
> emc_clear_entry(struct emc_entry *ce);
> +static void smc_clear_entry(struct smc_bucket *b, int idx);
>
> static void dp_netdev_request_reconfigure(struct dp_netdev *dp); static
> inline
> bool @@ -777,6 +817,24 @@ emc_cache_init(struct emc_cache *flow_cache)
> }
>
> static void
> +smc_cache_init(struct smc_cache *smc_cache) {
> + int i, j;
> + for (i = 0; i < SMC_BUCKET_CNT; i++) {
> + for (j = 0; j < SMC_ENTRY_PER_BUCKET; j++) {
> + smc_cache->buckets[i].flow_idx[j] = UINT16_MAX;
> + }
> + }
> +}
> +
> +static void
> +dfc_cache_init(struct dfc_cache *flow_cache) {
> + emc_cache_init(&flow_cache->emc_cache);
> + smc_cache_init(&flow_cache->smc_cache);
> +}
> +
> +static void
> emc_cache_uninit(struct emc_cache *flow_cache) {
> int i;
> @@ -786,6 +844,25 @@ emc_cache_uninit(struct emc_cache *flow_cache)
> }
> }
>
> +static void
> +smc_cache_uninit(struct smc_cache *smc) {
> + int i, j;
> +
> + for (i = 0; i < SMC_BUCKET_CNT; i++) {
> + for (j = 0; j < SMC_ENTRY_PER_BUCKET; j++) {
> + smc_clear_entry(&(smc->buckets[i]), j);
> + }
> + }
> +}
> +
> +static void
> +dfc_cache_uninit(struct dfc_cache *flow_cache) {
> + smc_cache_uninit(&flow_cache->smc_cache);
> + emc_cache_uninit(&flow_cache->emc_cache);
> +}
> +
> /* Check and clear dead flow references slowly (one entry at each
> * invocation). */
> static void
> @@ -897,6 +974,7 @@ pmd_info_show_stats(struct ds *reply,
> " packet recirculations: %"PRIu64"\n"
> " avg. datapath passes per packet: %.02f\n"
> " emc hits: %"PRIu64"\n"
> + " smc hits: %"PRIu64"\n"
> " megaflow hits: %"PRIu64"\n"
> " avg. subtable lookups per megaflow hit: %.02f\n"
> " miss with success upcall: %"PRIu64"\n"
> @@ -904,6 +982,7 @@ pmd_info_show_stats(struct ds *reply,
> " avg. packets per output batch: %.02f\n",
> total_packets, stats[PMD_STAT_RECIRC],
> passes_per_pkt, stats[PMD_STAT_EXACT_HIT],
> + stats[PMD_STAT_SMC_HIT],
> stats[PMD_STAT_MASKED_HIT], lookups_per_hit,
> stats[PMD_STAT_MISS], stats[PMD_STAT_LOST],
> packets_per_batch);
> @@ -1617,6 +1696,7 @@ dpif_netdev_get_stats(const struct dpif *dpif, struct
> dpif_dp_stats *stats)
> stats->n_flows += cmap_count(&pmd->flow_table);
> pmd_perf_read_counters(&pmd->perf_stats, pmd_stats);
> stats->n_hit += pmd_stats[PMD_STAT_EXACT_HIT];
> + stats->n_hit += pmd_stats[PMD_STAT_SMC_HIT];
> stats->n_hit += pmd_stats[PMD_STAT_MASKED_HIT];
> stats->n_missed += pmd_stats[PMD_STAT_MISS];
> stats->n_lost += pmd_stats[PMD_STAT_LOST]; @@ -2721,10 +2801,11
> @@ emc_probabilistic_insert(struct dp_netdev_pmd_thread *pmd,
> * probability of 1/100 ie. 1% */
>
> uint32_t min;
> +
> atomic_read_relaxed(&pmd->dp->emc_insert_min, &min);
>
> if (min && random_uint32() <= min) {
> - emc_insert(&pmd->flow_cache, key, flow);
> + emc_insert(&(pmd->flow_cache).emc_cache, key, flow);
> }
> }
>
> @@ -2746,6 +2827,86 @@ emc_lookup(struct emc_cache *cache, const struct
> netdev_flow_key *key)
> return NULL;
> }
>
> +static inline const struct cmap_node *
> +smc_entry_get(struct dp_netdev_pmd_thread *pmd, const uint32_t hash) {
> + struct smc_cache *cache = &(pmd->flow_cache).smc_cache;
> + struct smc_bucket *bucket = &cache->buckets[hash & SMC_MASK];
> + uint16_t sig = hash >> 16;
> + uint16_t index = UINT16_MAX;
> +
> + for (int i = 0; i < SMC_ENTRY_PER_BUCKET; i++) {
> + if (bucket->sig[i] == sig) {
> + index = bucket->flow_idx[i];
> + break;
> + }
> + }
> + if (index != UINT16_MAX) {
> + return cmap_find_by_index(&pmd->flow_table, index);
> + }
> + return NULL;
> +}
> +
> +static void
> +smc_clear_entry(struct smc_bucket *b, int idx) {
> + b->flow_idx[idx] = UINT16_MAX;
> +}
> +
> +/* Insert the flow_table index into SMC. Insertion may fail when 1) SMC
> +is
> + * turned off, 2) the flow_table index is larger than uint16_t can handle.
> + * If there is already an SMC entry having same signature, the index
> +will be
> + * updated. If there is no existing entry, but an empty entry is
> +available,
> + * the empty entry will be taken. If no empty entry or existing same
> +signature,
> + * a random entry from the hashed bucket will be picked. */ static
> +inline void smc_insert(struct dp_netdev_pmd_thread *pmd,
> + const struct netdev_flow_key *key,
> + uint32_t hash)
> +{
> + struct smc_cache *smc_cache = &(pmd->flow_cache).smc_cache;
> + struct smc_bucket *bucket = &smc_cache->buckets[key->hash &
> SMC_MASK];
> + uint16_t index;
> + uint32_t cmap_index;
> + bool smc_enable_db;
> + int i;
> +
> + atomic_read_relaxed(&pmd->dp->smc_enable_db, &smc_enable_db);
> + if (!smc_enable_db) {
> + return;
> + }
> +
> + cmap_index = cmap_find_index(&pmd->flow_table, hash);
> + index = (cmap_index >= UINT16_MAX) ? UINT16_MAX :
> + (uint16_t)cmap_index;
> +
> + /* If the index is larger than SMC can handle (uint16_t), we don't
> + * insert */
> + if (index == UINT16_MAX) {
> + return;
> + }
> +
> + /* If an entry with same signature already exists, update the index */
> + uint16_t sig = key->hash >> 16;
> + for (i = 0; i < SMC_ENTRY_PER_BUCKET; i++) {
> + if (bucket->sig[i] == sig) {
> + bucket->flow_idx[i] = index;
> + return;
> + }
> + }
> + /* If there is an empty entry, occupy it. */
> + for (i = 0; i < SMC_ENTRY_PER_BUCKET; i++) {
> + if (bucket->flow_idx[i] == UINT16_MAX) {
> + bucket->sig[i] = sig;
> + bucket->flow_idx[i] = index;
> + return;
> + }
> + }
> + /* Otherwise, pick a random entry. */
> + i = random_uint32() % SMC_ENTRY_PER_BUCKET;
> + bucket->sig[i] = sig;
> + bucket->flow_idx[i] = index;
> +}
> +
> static struct dp_netdev_flow *
> dp_netdev_pmd_lookup_flow(struct dp_netdev_pmd_thread *pmd,
> const struct netdev_flow_key *key, @@ -2759,7
> +2920,7 @@
> dp_netdev_pmd_lookup_flow(struct dp_netdev_pmd_thread *pmd,
>
> cls = dp_netdev_pmd_lookup_dpcls(pmd, in_port);
> if (OVS_LIKELY(cls)) {
> - dpcls_lookup(cls, key, &rule, 1, lookup_num_p);
> + dpcls_lookup(cls, &key, &rule, 1, lookup_num_p);
> netdev_flow = dp_netdev_flow_cast(rule);
> }
> return netdev_flow;
> @@ -3606,6 +3767,17 @@ dpif_netdev_set_config(struct dpif *dpif, const
> struct smap *other_config)
> }
> }
>
> + bool smc_enable = smap_get_bool(other_config, "smc-enable", false);
> + bool cur_smc;
> + atomic_read_relaxed(&dp->smc_enable_db, &cur_smc);
> + if (smc_enable != cur_smc) {
> + atomic_store_relaxed(&dp->smc_enable_db, smc_enable);
> + if (smc_enable) {
> + VLOG_INFO("SMC cache is enabled");
> + } else {
> + VLOG_INFO("SMC cache is disabled");
> + }
> + }
> return 0;
> }
>
> @@ -4740,7 +4912,7 @@ pmd_thread_main(void *f_)
> ovs_numa_thread_setaffinity_core(pmd->core_id);
> dpdk_set_lcore_id(pmd->core_id);
> poll_cnt = pmd_load_queues_and_ports(pmd, &poll_list);
> - emc_cache_init(&pmd->flow_cache);
> + dfc_cache_init(&pmd->flow_cache);
> reload:
> pmd_alloc_static_tx_qid(pmd);
>
> @@ -4794,7 +4966,7 @@ reload:
> coverage_try_clear();
> dp_netdev_pmd_try_optimize(pmd, poll_list, poll_cnt);
> if (!ovsrcu_try_quiesce()) {
> - emc_cache_slow_sweep(&pmd->flow_cache);
> + emc_cache_slow_sweep(&((pmd->flow_cache).emc_cache));
> }
>
> atomic_read_relaxed(&pmd->reload, &reload); @@ -4819,7 +4991,7
> @@ reload:
> goto reload;
> }
>
> - emc_cache_uninit(&pmd->flow_cache);
> + dfc_cache_uninit(&pmd->flow_cache);
> free(poll_list);
> pmd_free_cached_ports(pmd);
> return NULL;
> @@ -5255,7 +5427,7 @@ dp_netdev_configure_pmd(struct
> dp_netdev_pmd_thread *pmd, struct dp_netdev *dp,
> /* init the 'flow_cache' since there is no
> * actual thread created for NON_PMD_CORE_ID. */
> if (core_id == NON_PMD_CORE_ID) {
> - emc_cache_init(&pmd->flow_cache);
> + dfc_cache_init(&pmd->flow_cache);
> pmd_alloc_static_tx_qid(pmd);
> }
> pmd_perf_stats_init(&pmd->perf_stats);
> @@ -5298,7 +5470,7 @@ dp_netdev_del_pmd(struct dp_netdev *dp, struct
> dp_netdev_pmd_thread *pmd)
> * but extra cleanup is necessary */
> if (pmd->core_id == NON_PMD_CORE_ID) {
> ovs_mutex_lock(&dp->non_pmd_mutex);
> - emc_cache_uninit(&pmd->flow_cache);
> + dfc_cache_uninit(&pmd->flow_cache);
> pmd_free_cached_ports(pmd);
> pmd_free_static_tx_qid(pmd);
> ovs_mutex_unlock(&dp->non_pmd_mutex);
> @@ -5602,10 +5774,72 @@ dp_netdev_queue_batches(struct dp_packet *pkt,
> packet_batch_per_flow_update(batch, pkt, tcp_flags); }
>
> -/* Try to process all ('cnt') the 'packets' using only the exact match cache
> +/* SMC lookup function for a batch of packets.
> + * By doing batching SMC lookup, we can use prefetch
> + * to hide memory access latency.
> + */
> +static inline void
> +smc_lookup_batch(struct dp_netdev_pmd_thread *pmd,
> + struct netdev_flow_key *keys,
> + struct netdev_flow_key **missed_keys,
> + struct dp_packet_batch *packets_,
> + struct packet_batch_per_flow batches[],
> + size_t *n_batches, const int cnt) {
> + int i;
> + struct dp_packet *packet;
> + size_t n_smc_hit = 0, n_missed = 0;
> + struct dfc_cache *cache = &pmd->flow_cache;
> + struct smc_cache *smc_cache = &cache->smc_cache;
> + const struct cmap_node *flow_node;
> +
> + /* Prefetch buckets for all packets */
> + for (i = 0; i < cnt; i++) {
> + OVS_PREFETCH(&smc_cache->buckets[keys[i].hash & SMC_MASK]);
> + }
> +
> + DP_PACKET_BATCH_REFILL_FOR_EACH (i, cnt, packet, packets_) {
> + struct dp_netdev_flow *flow = NULL;
> + flow_node = smc_entry_get(pmd, keys[i].hash);
> + bool hit = false;
> +
> + if (OVS_LIKELY(flow_node != NULL)) {
> + CMAP_NODE_FOR_EACH (flow, node, flow_node) {
> + /* Since we dont have per-port megaflow to check the port
> + * number, we need to verify that the input ports match. */
> + if (OVS_LIKELY(dpcls_rule_matches_key(&flow->cr, &keys[i]) &&
> + flow->flow.in_port.odp_port == packet->md.in_port.odp_port))
> {
> + /* SMC hit and emc miss, we insert into EMC */
> + emc_probabilistic_insert(pmd, &keys[i], flow);
> + keys[i].len =
> + netdev_flow_key_size(miniflow_n_values(&keys[i].mf));
> + dp_netdev_queue_batches(packet, flow,
> + miniflow_get_tcp_flags(&keys[i].mf), batches, n_batches);
> + n_smc_hit++;
> + hit = true;
> + break;
> + }
> + }
> + if (hit) {
> + continue;
> + }
> + }
> +
> + /* SMC missed. Group missed packets together at
> + * the beginning of the 'packets' array. */
> + dp_packet_batch_refill(packets_, packet, i);
> + /* Put missed keys to the pointer arrays return to the caller */
> + missed_keys[n_missed++] = &keys[i];
> + }
> +
> + pmd_perf_update_counter(&pmd->perf_stats, PMD_STAT_SMC_HIT,
> +n_smc_hit); }
> +
> +/* Try to process all ('cnt') the 'packets' using only the datapath
> +flow cache
> * 'pmd->flow_cache'. If a flow is not found for a packet 'packets[i]', the
> * miniflow is copied into 'keys' and the packet pointer is moved at the
> - * beginning of the 'packets' array.
> + * beginning of the 'packets' array. The pointers of missed keys are
> + put in the
> + * missed_keys pointer array for future processing.
> *
> * The function returns the number of packets that needs to be processed in
> the
> * 'packets' array (they have been moved to the beginning of the vector).
> @@ -5617,21 +5851,24 @@ dp_netdev_queue_batches(struct dp_packet *pkt,
> * will be ignored.
> */
> static inline size_t
> -emc_processing(struct dp_netdev_pmd_thread *pmd,
> +dfc_processing(struct dp_netdev_pmd_thread *pmd,
> struct dp_packet_batch *packets_,
> struct netdev_flow_key *keys,
> + struct netdev_flow_key **missed_keys,
> struct packet_batch_per_flow batches[], size_t *n_batches,
> bool md_is_valid, odp_port_t port_no) {
> - struct emc_cache *flow_cache = &pmd->flow_cache;
> struct netdev_flow_key *key = &keys[0];
> - size_t n_missed = 0, n_dropped = 0;
> + size_t n_missed = 0, n_emc_hit = 0;
> + struct dfc_cache *cache = &pmd->flow_cache;
> struct dp_packet *packet;
> const size_t cnt = dp_packet_batch_size(packets_);
> uint32_t cur_min;
> int i;
> uint16_t tcp_flags;
> + bool smc_enable_db;
>
> + atomic_read_relaxed(&pmd->dp->smc_enable_db, &smc_enable_db);
> atomic_read_relaxed(&pmd->dp->emc_insert_min, &cur_min);
> pmd_perf_update_counter(&pmd->perf_stats,
> md_is_valid ? PMD_STAT_RECIRC : PMD_STAT_RECV,
> @@ -
> 5643,7 +5880,6 @@ emc_processing(struct dp_netdev_pmd_thread *pmd,
>
> if (OVS_UNLIKELY(dp_packet_size(packet) < ETH_HEADER_LEN)) {
> dp_packet_delete(packet);
> - n_dropped++;
> continue;
> }
>
> @@ -5671,15 +5907,17 @@ emc_processing(struct dp_netdev_pmd_thread
> *pmd,
>
> miniflow_extract(packet, &key->mf);
> key->len = 0; /* Not computed yet. */
> - /* If EMC is disabled skip hash computation and emc_lookup */
> - if (cur_min) {
> + /* If EMC and SMC disabled skip hash computation */
> + if (smc_enable_db == true || cur_min != 0) {
> if (!md_is_valid) {
> key->hash = dpif_netdev_packet_get_rss_hash_orig_pkt(packet,
> &key->mf);
> } else {
> key->hash = dpif_netdev_packet_get_rss_hash(packet,
> &key->mf);
> }
> - flow = emc_lookup(flow_cache, key);
> + }
> + if (cur_min) {
> + flow = emc_lookup(&cache->emc_cache, key);
> } else {
> flow = NULL;
> }
> @@ -5687,19 +5925,30 @@ emc_processing(struct dp_netdev_pmd_thread
> *pmd,
> tcp_flags = miniflow_get_tcp_flags(&key->mf);
> dp_netdev_queue_batches(packet, flow, tcp_flags, batches,
> n_batches);
> + n_emc_hit++;
> } else {
> /* Exact match cache missed. Group missed packets together at
> * the beginning of the 'packets' array. */
> dp_packet_batch_refill(packets_, packet, i);
> /* 'key[n_missed]' contains the key of the current packet and it
> - * must be returned to the caller. The next key should be
> extracted
> - * to 'keys[n_missed + 1]'. */
> + * will be passed to SMC lookup. The next key should be extracted
> + * to 'keys[n_missed + 1]'.
> + * We also maintain a pointer array to keys missed both SMC and
> EMC
> + * which will be returned to the caller for future processing. */
> + missed_keys[n_missed] = key;
> key = &keys[++n_missed];
> }
> }
>
> - pmd_perf_update_counter(&pmd->perf_stats, PMD_STAT_EXACT_HIT,
> - cnt - n_dropped - n_missed);
> + pmd_perf_update_counter(&pmd->perf_stats, PMD_STAT_EXACT_HIT,
> + n_emc_hit);
> +
> + if (!smc_enable_db) {
> + return dp_packet_batch_size(packets_);
> + }
> +
> + /* Packets miss EMC will do a batch lookup in SMC if enabled */
> + smc_lookup_batch(pmd, keys, missed_keys, packets_, batches,
> + n_batches, n_missed);
>
> return dp_packet_batch_size(packets_); } @@ -5767,6 +6016,8 @@
> handle_packet_upcall(struct dp_netdev_pmd_thread *pmd,
> add_actions->size);
> }
> ovs_mutex_unlock(&pmd->flow_mutex);
> + uint32_t hash = dp_netdev_flow_hash(&netdev_flow->ufid);
> + smc_insert(pmd, key, hash);
> emc_probabilistic_insert(pmd, key, netdev_flow);
> }
> if (pmd_perf_metrics_enabled(pmd)) { @@ -5783,7 +6034,7 @@
> handle_packet_upcall(struct dp_netdev_pmd_thread *pmd, static inline void
> fast_path_processing(struct dp_netdev_pmd_thread *pmd,
> struct dp_packet_batch *packets_,
> - struct netdev_flow_key *keys,
> + struct netdev_flow_key **keys,
> struct packet_batch_per_flow batches[],
> size_t *n_batches,
> odp_port_t in_port) @@ -5805,12 +6056,13 @@
> fast_path_processing(struct dp_netdev_pmd_thread *pmd,
>
> for (size_t i = 0; i < cnt; i++) {
> /* Key length is needed in all the cases, hash computed on demand. */
> - keys[i].len = netdev_flow_key_size(miniflow_n_values(&keys[i].mf));
> + keys[i]->len =
> + netdev_flow_key_size(miniflow_n_values(&keys[i]->mf));
> }
> /* Get the classifier for the in_port */
> cls = dp_netdev_pmd_lookup_dpcls(pmd, in_port);
> if (OVS_LIKELY(cls)) {
> - any_miss = !dpcls_lookup(cls, keys, rules, cnt, &lookup_cnt);
> + any_miss = !dpcls_lookup(cls, (const struct netdev_flow_key **)keys,
> + rules, cnt, &lookup_cnt);
> } else {
> any_miss = true;
> memset(rules, 0, sizeof(rules)); @@ -5832,7 +6084,7 @@
> fast_path_processing(struct dp_netdev_pmd_thread *pmd,
> /* It's possible that an earlier slow path execution installed
> * a rule covering this flow. In this case, it's a lot cheaper
> * to catch it here than execute a miss. */
> - netdev_flow = dp_netdev_pmd_lookup_flow(pmd, &keys[i],
> + netdev_flow = dp_netdev_pmd_lookup_flow(pmd, keys[i],
> &add_lookup_cnt);
> if (netdev_flow) {
> lookup_cnt += add_lookup_cnt; @@ -5840,7 +6092,7 @@
> fast_path_processing(struct dp_netdev_pmd_thread *pmd,
> continue;
> }
>
> - int error = handle_packet_upcall(pmd, packet, &keys[i],
> + int error = handle_packet_upcall(pmd, packet, keys[i],
> &actions, &put_actions);
>
> if (OVS_UNLIKELY(error)) {
> @@ -5870,10 +6122,12 @@ fast_path_processing(struct
> dp_netdev_pmd_thread *pmd,
> }
>
> flow = dp_netdev_flow_cast(rules[i]);
> + uint32_t hash = dp_netdev_flow_hash(&flow->ufid);
> + smc_insert(pmd, keys[i], hash);
>
> - emc_probabilistic_insert(pmd, &keys[i], flow);
> + emc_probabilistic_insert(pmd, keys[i], flow);
> dp_netdev_queue_batches(packet, flow,
> - miniflow_get_tcp_flags(&keys[i].mf),
> + miniflow_get_tcp_flags(&keys[i]->mf),
> batches, n_batches);
> }
>
> @@ -5904,17 +6158,18 @@ dp_netdev_input__(struct dp_netdev_pmd_thread
> *pmd, #endif
> OVS_ALIGNED_VAR(CACHE_LINE_SIZE)
> struct netdev_flow_key keys[PKT_ARRAY_SIZE];
> + struct netdev_flow_key *missed_keys[PKT_ARRAY_SIZE];
> struct packet_batch_per_flow batches[PKT_ARRAY_SIZE];
> size_t n_batches;
> odp_port_t in_port;
>
> n_batches = 0;
> - emc_processing(pmd, packets, keys, batches, &n_batches,
> + dfc_processing(pmd, packets, keys, missed_keys, batches,
> + &n_batches,
> md_is_valid, port_no);
> if (!dp_packet_batch_is_empty(packets)) {
> /* Get ingress port from first packet's metadata. */
> in_port = packets->packets[0]->md.in_port.odp_port;
> - fast_path_processing(pmd, packets, keys,
> + fast_path_processing(pmd, packets, missed_keys,
> batches, &n_batches, in_port);
> }
>
> @@ -6864,7 +7119,7 @@ dpcls_remove(struct dpcls *cls, struct dpcls_rule
> *rule)
>
> /* Returns true if 'target' satisfies 'key' in 'mask', that is, if each 1-bit
> * in 'mask' the values in 'key' and 'target' are the same. */ -static
> inline bool
> +static bool
> dpcls_rule_matches_key(const struct dpcls_rule *rule,
> const struct netdev_flow_key *target) { @@ -6891,7
> +7146,7 @@
> dpcls_rule_matches_key(const struct dpcls_rule *rule,
> *
> * Returns true if all miniflows found a corresponding rule. */ static bool
> -
> dpcls_lookup(struct dpcls *cls, const struct netdev_flow_key keys[],
> +dpcls_lookup(struct dpcls *cls, const struct netdev_flow_key *keys[],
> struct dpcls_rule **rules, const size_t cnt,
> int *num_lookups_p)
> {
> @@ -6930,7 +7185,7 @@ dpcls_lookup(struct dpcls *cls, const struct
> netdev_flow_key keys[],
> * masked with the subtable's mask to avoid hashing the wildcarded
> * bits. */
> ULLONG_FOR_EACH_1(i, keys_map) {
> - hashes[i] = netdev_flow_key_hash_in_mask(&keys[i],
> + hashes[i] = netdev_flow_key_hash_in_mask(keys[i],
> &subtable->mask);
> }
> /* Lookup. */
> @@ -6944,7 +7199,7 @@ dpcls_lookup(struct dpcls *cls, const struct
> netdev_flow_key keys[],
> struct dpcls_rule *rule;
>
> CMAP_NODE_FOR_EACH (rule, cmap_node, nodes[i]) {
> - if (OVS_LIKELY(dpcls_rule_matches_key(rule, &keys[i]))) {
> + if (OVS_LIKELY(dpcls_rule_matches_key(rule, keys[i])))
> + {
> rules[i] = rule;
> /* Even at 20 Mpps the 32-bit hit_cnt cannot wrap
> * within one second optimization interval. */ diff --git
> a/tests/pmd.at b/tests/pmd.at index f3fac63..60452f5 100644
> --- a/tests/pmd.at
> +++ b/tests/pmd.at
> @@ -185,6 +185,7 @@ CHECK_PMD_THREADS_CREATED() AT_CHECK([ovs-
> appctl vlog/set dpif_netdev:dbg]) AT_CHECK([ovs-ofctl add-flow br0
> action=normal]) AT_CHECK([ovs-vsctl set Open_vSwitch . other_config:emc-
> insert-inv-prob=1])
> +AT_CHECK([ovs-vsctl set Open_vSwitch . other_config:smc-enable=true])
>
> sleep 1
>
> diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index
> 63a3a2e..6342949 100644
> --- a/vswitchd/vswitch.xml
> +++ b/vswitchd/vswitch.xml
> @@ -405,6 +405,19 @@
> </p>
> </column>
>
> + <column name="other_config" key="smc-enable"
> + type='{"type": "boolean"}'>
> + <p>
> + Signature match cache or SMC is a cache between EMC and megaflow
> + cache. It does not store the full key of the flow, so it is more
> + memory efficient comparing to EMC cache. SMC is especially useful
> + when flow count is larger than EMC capacity.
> + </p>
> + <p>
> + Defaults to false but can be changed at any time.
> + </p>
> + </column>
> +
> <column name="other_config" key="n-handler-threads"
> type='{"type": "integer", "minInteger": 1}'>
> <p>
> --
> 2.7.4
_______________________________________________
dev mailing list
[email protected]
https://mail.openvswitch.org/mailman/listinfo/ovs-dev
