> Acked-by: Billy O'Mahony <billy.o.mah...@intel.com>
>
Thanks to all for the work on this.
I've applied this to dpdk_merge branch, it will be part of this week's pull
request.
I rolled patch 2 of the series into the same commit as I don't think it makes
sense to have a broken unit test for the 1st commit.
Thanks
Ian
> > -----Original Message-----
> > From: Wang, Yipeng1
> > Sent: Tuesday, July 10, 2018 11:14 AM
> > To: d...@openvswitch.org; jan.scheur...@ericsson.com; O Mahony, Billy
> > <billy.o.mah...@intel.com>
> > Cc: Wang, Yipeng1 <yipeng1.w...@intel.com>; Stokes, Ian
> > <ian.sto...@intel.com>; b...@ovn.org
> > 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 <yipeng1.w...@intel.com>
> > Co-authored-by: Jan Scheurich <jan.scheur...@ericsson.com>
> > Signed-off-by: Jan Scheurich <jan.scheur...@ericsson.com>
> > ---
> > 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
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