[ovs-dev] [PATCH] ofproto-dpif: Remove the flow_dumper thread.

Joe Stringer joe at wand.net.nz
Wed Apr 9 04:36:50 UTC 2014


Thanks Alex.

There is also one minor fix to be rolled in:

@@ -1403,8 +1416,8 @@ revalidate_ukey(struct udpif *udpif, struct udpif_key
*ukey,
         compose_slow_path(udpif, &xout, odp_in_port, &xout_actions);
     }

-    if (actions_len != xout_actions.size
-        || memcmp(xout_actions.data, actions, actions_len)) {
+    if (actions_len != ofpbuf_size(&xout_actions)
+        || memcmp(ofpbuf_data(&xout_actions), actions, actions_len)) {
         goto exit;
     }

I will wait for further review. Let me know if I should repost.


On 9 April 2014 10:06, Alex Wang <alexw at nicira.com> wrote:

> Looks good to me, the structure is much clearer,
>
> I think this should be also reviewed by Ben or Ethan,
>
> Alex Wang,
>
>
> On Tue, Apr 8, 2014 at 3:03 PM, Joe Stringer <joestringer at nicira.com>wrote:
>
>> From: Joe Stringer <joe at wand.net.nz>
>> Date: 8 April 2014 15:58
>> Subject: [PATCH] ofproto-dpif: Remove the flow_dumper thread.
>> To: dev at openvswitch.org
>> Cc: Ethan Jackson <ethan at nicira.com>, Joe Stringer <
>> joestringer at nicira.com>
>>
>>
>> From: Ethan Jackson <ethan at nicira.com>
>>
>> Previously, we had a separate flow_dumper thread that fetched flows from
>> the datapath to distribute to revalidator threads. This patch takes the
>> logic for dumping and pushes it into the revalidator threads, resulting
>> in simpler code with similar performance to the current code.
>>
>> One thread, the "leader", is responsible for beginning and ending each
>> flow dump, maintaining the flow_limit, and checking whether the
>> revalidator threads need to exit. All revalidator threads dump,
>> revalidate, delete datapath flows and garbage collect ukeys.
>>
>> Co-authored-by: Joe Stringer <joestringer at nicira.com>
>> Signed-off-by: Joe Stringer <joestringer at nicira.com>
>> ---
>> v7: Add back logic (present in master) that deletes all flows older than
>>      100ms if we are currently exceeding the flow limit.
>>     Rebase.
>> v6: Shift ukeys hmaps from revalidators into udpif.
>>     Documentation tidyups.
>> v5: Handle ukey creation race.
>>     Style fixes.
>> v4: Rebase.
>> v3: First post.
>> ---
>>  ofproto/ofproto-dpif-upcall.c |  632
>> +++++++++++++++++++----------------------
>>  1 file changed, 300 insertions(+), 332 deletions(-)
>>
>> diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
>> index 938cfde..894dd15 100644
>> --- a/ofproto/ofproto-dpif-upcall.c
>> +++ b/ofproto/ofproto-dpif-upcall.c
>> @@ -67,34 +67,27 @@ struct handler {
>>                                            'mutex'. */
>>  };
>>
>> -/* A thread that processes each kernel flow handed to it by the
>> flow_dumper
>> - * thread, updates OpenFlow statistics, and updates or removes the
>> kernel flow
>> - * as necessary. */
>> +/* A thread that processes datapath flows, updates OpenFlow statistics,
>> and
>> + * updates or removes them if necessary. */
>>  struct revalidator {
>>      struct udpif *udpif;               /* Parent udpif. */
>>      char *name;                        /* Thread name. */
>>
>>      pthread_t thread;                  /* Thread ID. */
>> -    struct hmap ukeys;                 /* Datapath flow keys. */
>> -
>> -    uint64_t dump_seq;
>> -
>> -    struct ovs_mutex mutex;            /* Mutex guarding the following.
>> */
>> -    pthread_cond_t wake_cond;
>> -    struct list udumps OVS_GUARDED;    /* Unprocessed udumps. */
>> -    size_t n_udumps OVS_GUARDED;       /* Number of unprocessed udumps.
>> */
>> +    struct hmap *ukeys;                /* Points into udpif->ukeys for
>> this
>> +                                          revalidator. Used for GC
>> phase. */
>>  };
>>
>>  /* An upcall handler for ofproto_dpif.
>>   *
>>   * udpif has two logically separate pieces:
>>   *
>> - *    - A "dispatcher" thread that reads upcalls from the kernel and
>> dispatches
>> - *      them to one of several "handler" threads (see struct handler).
>> + *    - Miss handling threads led by a "dispatcher" thread that reads
>> upcalls
>> + *      from the kernel and dispatches them to one of several "handler"
>> threads
>> + *      (see struct handler).
>>   *
>> - *    - A "flow_dumper" thread that reads the kernel flow table and
>> dispatches
>> - *      flows to one of several "revalidator" threads (see struct
>> - *      revalidator). */
>> + *    - Revalidation threads which read the datapath flow table and
>> maintains
>> + *      them. */
>>  struct udpif {
>>      struct list list_node;             /* In all_udpifs list. */
>>
>> @@ -104,7 +97,6 @@ struct udpif {
>>      uint32_t secret;                   /* Random seed for upcall hash. */
>>
>>      pthread_t dispatcher;              /* Dispatcher thread ID. */
>> -    pthread_t flow_dumper;             /* Flow dumper thread ID. */
>>
>>      struct handler *handlers;          /* Upcall handlers. */
>>      size_t n_handlers;
>> @@ -112,14 +104,24 @@ struct udpif {
>>      struct revalidator *revalidators;  /* Flow revalidators. */
>>      size_t n_revalidators;
>>
>> -    uint64_t last_reval_seq;           /* 'reval_seq' at last
>> revalidation. */
>> -    struct seq *reval_seq;             /* Incremented to force
>> revalidation. */
>> -
>> -    struct seq *dump_seq;              /* Increments each dump
>> iteration. */
>> -
>>      struct latch exit_latch;           /* Tells child threads to exit. */
>>
>> +    /* Revalidation. */
>> +    struct seq *reval_seq;             /* Incremented to force
>> revalidation. */
>> +    bool need_revalidate;              /* As indicated by 'reval_seq'. */
>> +    bool reval_exit;                   /* Set by leader on 'exit_latch.
>> */
>> +    pthread_barrier_t reval_barrier;   /* Barrier used by revalidators.
>> */
>> +    struct dpif_flow_dump dump;        /* DPIF flow dump state. */
>>      long long int dump_duration;       /* Duration of the last flow
>> dump. */
>> +    struct seq *dump_seq;              /* Increments each dump
>> iteration. */
>> +
>> +    /* During the flow dump phase, revalidators insert into these with a
>> random
>> +     * distribution. During the garbage collection phase, each
>> revalidator
>> +     * takes care of garbage collecting one of these hmaps. */
>> +    struct {
>> +        struct ovs_mutex mutex;        /* Guards the following. */
>> +        struct hmap hmap OVS_GUARDED;  /* Datapath flow keys. */
>> +    } *ukeys;
>>
>>      /* Datapath flow statistics. */
>>      unsigned int max_n_flows;
>> @@ -155,40 +157,28 @@ struct upcall {
>>  /* 'udpif_key's are responsible for tracking the little bit of state
>> udpif
>>   * needs to do flow expiration which can't be pulled directly from the
>>   * datapath.  They are owned, created by, maintained, and destroyed by a
>> single
>> - * revalidator making them easy to efficiently handle with multiple
>> threads. */
>> + * revalidator making them easy to efficiently handle with multiple
>> threads.
>> + *
>> + * While some elements of a udpif_key are protected by a mutex, the ukey
>> itself
>> + * is not.  Therefore it is not safe to destroy a udpif_key except when
>> all
>> + * revalidators are in garbage collection phase, or they aren't running.
>> */
>>  struct udpif_key {
>>      struct hmap_node hmap_node;     /* In parent revalidator 'ukeys'
>> map. */
>>
>> -    struct nlattr *key;            /* Datapath flow key. */
>> +    /* These elements are read only once created, and therefore aren't
>> +     * protected by a mutex. */
>> +    const struct nlattr *key;      /* Datapath flow key. */
>>      size_t key_len;                /* Length of 'key'. */
>>
>> -    struct dpif_flow_stats stats;  /* Stats at most recent flow dump. */
>> -    long long int created;         /* Estimation of creation time. */
>> -
>> -    bool mark;                     /* Used by mark and sweep GC
>> algorithm. */
>> +    struct ovs_mutex mutex;                   /* Guards the following. */
>> +    struct dpif_flow_stats stats OVS_GUARDED; /* Last known stats.*/
>> +    long long int created OVS_GUARDED;        /* Estimate of creation
>> time. */
>> +    bool mark OVS_GUARDED;                    /* For mark and sweep
>> garbage
>> +                                                 collection. */
>> +    bool flow_exists OVS_GUARDED;             /* Ensures flows are only
>> deleted
>> +                                                 once. */
>>
>> -    struct odputil_keybuf key_buf; /* Memory for 'key'. */
>> -};
>> -
>> -/* 'udpif_flow_dump's hold the state associated with one iteration in a
>> flow
>> - * dump operation.  This is created by the flow_dumper thread and handed
>> to the
>> - * appropriate revalidator thread to be processed. */
>> -struct udpif_flow_dump {
>> -    struct list list_node;
>> -
>> -    struct nlattr *key;            /* Datapath flow key. */
>> -    size_t key_len;                /* Length of 'key'. */
>> -    uint32_t key_hash;             /* Hash of 'key'. */
>> -
>> -    struct odputil_keybuf mask_buf;
>> -    struct nlattr *mask;           /* Datapath mask for 'key'. */
>> -    size_t mask_len;               /* Length of 'mask'. */
>> -
>> -    struct dpif_flow_stats stats;  /* Stats pulled from the datapath. */
>> -
>> -    bool need_revalidate;          /* Key needs revalidation? */
>> -
>> -    struct odputil_keybuf key_buf;
>> +    struct odputil_keybuf key_buf;            /* Memory for 'key'. */
>>  };
>>
>>  /* Flow miss batching.
>> @@ -223,12 +213,11 @@ static struct list all_udpifs =
>> LIST_INITIALIZER(&all_udpifs);
>>
>>  static void recv_upcalls(struct udpif *);
>>  static void handle_upcalls(struct handler *handler, struct list
>> *upcalls);
>> -static void *udpif_flow_dumper(void *);
>>  static void *udpif_dispatcher(void *);
>>  static void *udpif_upcall_handler(void *);
>>  static void *udpif_revalidator(void *);
>>  static uint64_t udpif_get_n_flows(struct udpif *);
>> -static void revalidate_udumps(struct revalidator *, struct list *udumps);
>> +static void revalidate(struct revalidator *);
>>  static void revalidator_sweep(struct revalidator *);
>>  static void revalidator_purge(struct revalidator *);
>>  static void upcall_unixctl_show(struct unixctl_conn *conn, int argc,
>> @@ -239,6 +228,9 @@ static void upcall_unixctl_enable_megaflows(struct
>> unixctl_conn *, int argc,
>>                                              const char *argv[], void
>> *aux);
>>  static void upcall_unixctl_set_flow_limit(struct unixctl_conn *conn, int
>> argc,
>>                                              const char *argv[], void
>> *aux);
>> +
>> +static struct udpif_key *ukey_create(const struct nlattr *key, size_t
>> key_len,
>> +                                     long long int used);
>>  static void ukey_delete(struct revalidator *, struct udpif_key *);
>>
>>  static atomic_bool enable_megaflows = ATOMIC_VAR_INIT(true);
>> @@ -319,34 +311,21 @@ udpif_set_threads(struct udpif *udpif, size_t
>> n_handlers,
>>          }
>>
>>          for (i = 0; i < udpif->n_revalidators; i++) {
>> -            struct revalidator *revalidator = &udpif->revalidators[i];
>> -
>> -            ovs_mutex_lock(&revalidator->mutex);
>> -            xpthread_cond_signal(&revalidator->wake_cond);
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> -            xpthread_join(revalidator->thread, NULL);
>> +            xpthread_join(udpif->revalidators[i].thread, NULL);
>>          }
>>
>> -        xpthread_join(udpif->flow_dumper, NULL);
>>          xpthread_join(udpif->dispatcher, NULL);
>>
>>          for (i = 0; i < udpif->n_revalidators; i++) {
>>              struct revalidator *revalidator = &udpif->revalidators[i];
>> -            struct udpif_flow_dump *udump, *next_udump;
>> -
>> -            LIST_FOR_EACH_SAFE (udump, next_udump, list_node,
>> -                                &revalidator->udumps) {
>> -                list_remove(&udump->list_node);
>> -                free(udump);
>> -            }
>>
>>              /* Delete ukeys, and delete all flows from the datapath to
>> prevent
>>               * double-counting stats. */
>>              revalidator_purge(revalidator);
>> -            hmap_destroy(&revalidator->ukeys);
>> -            ovs_mutex_destroy(&revalidator->mutex);
>> -
>>              free(revalidator->name);
>> +
>> +            hmap_destroy(&udpif->ukeys[i].hmap);
>> +            ovs_mutex_destroy(&udpif->ukeys[i].mutex);
>>          }
>>
>>          for (i = 0; i < udpif->n_handlers; i++) {
>> @@ -364,6 +343,8 @@ udpif_set_threads(struct udpif *udpif, size_t
>> n_handlers,
>>          }
>>          latch_poll(&udpif->exit_latch);
>>
>> +        xpthread_barrier_destroy(&udpif->reval_barrier);
>> +
>>          free(udpif->revalidators);
>>          udpif->revalidators = NULL;
>>          udpif->n_revalidators = 0;
>> @@ -371,6 +352,9 @@ udpif_set_threads(struct udpif *udpif, size_t
>> n_handlers,
>>          free(udpif->handlers);
>>          udpif->handlers = NULL;
>>          udpif->n_handlers = 0;
>> +
>> +        free(udpif->ukeys);
>> +        udpif->ukeys = NULL;
>>      }
>>
>>      error = dpif_handlers_set(udpif->dpif, 1);
>> @@ -400,21 +384,23 @@ udpif_set_threads(struct udpif *udpif, size_t
>> n_handlers,
>>                              handler);
>>          }
>>
>> +        xpthread_barrier_init(&udpif->reval_barrier, NULL,
>> +                              udpif->n_revalidators);
>> +        udpif->reval_exit = false;
>>          udpif->revalidators = xzalloc(udpif->n_revalidators
>>                                        * sizeof *udpif->revalidators);
>> +        udpif->ukeys = xmalloc(sizeof *udpif->ukeys * n_revalidators);
>>          for (i = 0; i < udpif->n_revalidators; i++) {
>>              struct revalidator *revalidator = &udpif->revalidators[i];
>>
>>              revalidator->udpif = udpif;
>> -            list_init(&revalidator->udumps);
>> -            hmap_init(&revalidator->ukeys);
>> -            ovs_mutex_init(&revalidator->mutex);
>> -            xpthread_cond_init(&revalidator->wake_cond, NULL);
>> +            hmap_init(&udpif->ukeys[i].hmap);
>> +            ovs_mutex_init(&udpif->ukeys[i].mutex);
>> +            revalidator->ukeys = &udpif->ukeys[i].hmap;
>>              xpthread_create(&revalidator->thread, NULL,
>> udpif_revalidator,
>>                              revalidator);
>>          }
>>          xpthread_create(&udpif->dispatcher, NULL, udpif_dispatcher,
>> udpif);
>> -        xpthread_create(&udpif->flow_dumper, NULL, udpif_flow_dumper,
>> udpif);
>>      }
>>
>>      ovsrcu_quiesce_end();
>> @@ -459,7 +445,6 @@ udpif_get_memory_usage(struct udpif *udpif, struct
>> simap *usage)
>>      size_t i;
>>
>>      simap_increase(usage, "dispatchers", 1);
>> -    simap_increase(usage, "flow_dumpers", 1);
>>
>>      simap_increase(usage, "handlers", udpif->n_handlers);
>>      for (i = 0; i < udpif->n_handlers; i++) {
>> @@ -471,15 +456,9 @@ udpif_get_memory_usage(struct udpif *udpif, struct
>> simap *usage)
>>
>>      simap_increase(usage, "revalidators", udpif->n_revalidators);
>>      for (i = 0; i < udpif->n_revalidators; i++) {
>> -        struct revalidator *revalidator = &udpif->revalidators[i];
>> -        ovs_mutex_lock(&revalidator->mutex);
>> -        simap_increase(usage, "revalidator dumps",
>> revalidator->n_udumps);
>> -
>> -        /* XXX: This isn't technically thread safe because the
>> revalidator
>> -         * ukeys maps isn't protected by a mutex since it's per thread.
>> */
>> -        simap_increase(usage, "revalidator keys",
>> -                       hmap_count(&revalidator->ukeys));
>> -        ovs_mutex_unlock(&revalidator->mutex);
>> +        ovs_mutex_lock(&udpif->ukeys[i].mutex);
>> +        simap_increase(usage, "udpif keys",
>> hmap_count(&udpif->ukeys[i].hmap));
>> +        ovs_mutex_unlock(&udpif->ukeys[i].mutex);
>>      }
>>  }
>>
>> @@ -560,125 +539,6 @@ udpif_dispatcher(void *arg)
>>      return NULL;
>>  }
>>
>> -static void *
>> -udpif_flow_dumper(void *arg)
>> -{
>> -    struct udpif *udpif = arg;
>> -
>> -    set_subprogram_name("flow_dumper");
>> -    while (!latch_is_set(&udpif->exit_latch)) {
>> -        const struct dpif_flow_stats *stats;
>> -        long long int start_time, duration;
>> -        const struct nlattr *key, *mask;
>> -        struct dpif_flow_dump dump;
>> -        size_t key_len, mask_len;
>> -        unsigned int flow_limit;
>> -        bool need_revalidate;
>> -        uint64_t reval_seq;
>> -        size_t n_flows, i;
>> -        int error;
>> -        void *state = NULL;
>> -
>> -        reval_seq = seq_read(udpif->reval_seq);
>> -        need_revalidate = udpif->last_reval_seq != reval_seq;
>> -        udpif->last_reval_seq = reval_seq;
>> -
>> -        n_flows = udpif_get_n_flows(udpif);
>> -        udpif->max_n_flows = MAX(n_flows, udpif->max_n_flows);
>> -        udpif->avg_n_flows = (udpif->avg_n_flows + n_flows) / 2;
>> -
>> -        start_time = time_msec();
>> -        error = dpif_flow_dump_start(&dump, udpif->dpif);
>> -        if (error) {
>> -            VLOG_INFO("Failed to start flow dump (%s)",
>> ovs_strerror(error));
>> -            goto skip;
>> -        }
>> -        dpif_flow_dump_state_init(udpif->dpif, &state);
>> -        while (dpif_flow_dump_next(&dump, state, &key, &key_len,
>> -                                   &mask, &mask_len, NULL, NULL, &stats)
>> -               && !latch_is_set(&udpif->exit_latch)) {
>> -            struct udpif_flow_dump *udump = xmalloc(sizeof *udump);
>> -            struct revalidator *revalidator;
>> -
>> -            udump->key_hash = hash_bytes(key, key_len, udpif->secret);
>> -            memcpy(&udump->key_buf, key, key_len);
>> -            udump->key = (struct nlattr *) &udump->key_buf;
>> -            udump->key_len = key_len;
>> -
>> -            memcpy(&udump->mask_buf, mask, mask_len);
>> -            udump->mask = (struct nlattr *) &udump->mask_buf;
>> -            udump->mask_len = mask_len;
>> -
>> -            udump->stats = *stats;
>> -            udump->need_revalidate = need_revalidate;
>> -
>> -            revalidator = &udpif->revalidators[udump->key_hash
>> -                % udpif->n_revalidators];
>> -
>> -            ovs_mutex_lock(&revalidator->mutex);
>> -            while (revalidator->n_udumps >= REVALIDATE_MAX_BATCH * 3
>> -                   && !latch_is_set(&udpif->exit_latch)) {
>> -                ovs_mutex_cond_wait(&revalidator->wake_cond,
>> -                                    &revalidator->mutex);
>> -            }
>> -            list_push_back(&revalidator->udumps, &udump->list_node);
>> -            revalidator->n_udumps++;
>> -            xpthread_cond_signal(&revalidator->wake_cond);
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> -        }
>> -        dpif_flow_dump_state_uninit(udpif->dpif, state);
>> -        dpif_flow_dump_done(&dump);
>> -
>> -        /* Let all the revalidators finish and garbage collect. */
>> -        seq_change(udpif->dump_seq);
>> -        for (i = 0; i < udpif->n_revalidators; i++) {
>> -            struct revalidator *revalidator = &udpif->revalidators[i];
>> -            ovs_mutex_lock(&revalidator->mutex);
>> -            xpthread_cond_signal(&revalidator->wake_cond);
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> -        }
>> -
>> -        for (i = 0; i < udpif->n_revalidators; i++) {
>> -            struct revalidator *revalidator = &udpif->revalidators[i];
>> -
>> -            ovs_mutex_lock(&revalidator->mutex);
>> -            while (revalidator->dump_seq != seq_read(udpif->dump_seq)
>> -                   && !latch_is_set(&udpif->exit_latch)) {
>> -                ovs_mutex_cond_wait(&revalidator->wake_cond,
>> -                                    &revalidator->mutex);
>> -            }
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> -        }
>> -
>> -        duration = MAX(time_msec() - start_time, 1);
>> -        udpif->dump_duration = duration;
>> -        atomic_read(&udpif->flow_limit, &flow_limit);
>> -        if (duration > 2000) {
>> -            flow_limit /= duration / 1000;
>> -        } else if (duration > 1300) {
>> -            flow_limit = flow_limit * 3 / 4;
>> -        } else if (duration < 1000 && n_flows > 2000
>> -                   && flow_limit < n_flows * 1000 / duration) {
>> -            flow_limit += 1000;
>> -        }
>> -        flow_limit = MIN(ofproto_flow_limit, MAX(flow_limit, 1000));
>> -        atomic_store(&udpif->flow_limit, flow_limit);
>> -
>> -        if (duration > 2000) {
>> -            VLOG_INFO("Spent an unreasonably long %lldms dumping flows",
>> -                      duration);
>> -        }
>> -
>> -skip:
>> -        poll_timer_wait_until(start_time + MIN(ofproto_max_idle, 500));
>> -        seq_wait(udpif->reval_seq, udpif->last_reval_seq);
>> -        latch_wait(&udpif->exit_latch);
>> -        poll_block();
>> -    }
>> -
>> -    return NULL;
>> -}
>> -
>>  /* The miss handler thread is responsible for processing miss upcalls
>> retrieved
>>   * by the dispatcher thread.  Once finished it passes the processed miss
>>   * upcalls to ofproto-dpif where they're installed in the datapath. */
>> @@ -723,42 +583,85 @@ udpif_upcall_handler(void *arg)
>>  static void *
>>  udpif_revalidator(void *arg)
>>  {
>> +    /* Used by all revalidators. */
>>      struct revalidator *revalidator = arg;
>> +    struct udpif *udpif = revalidator->udpif;
>> +    bool leader = revalidator == &udpif->revalidators[0];
>> +
>> +    /* Used only by the leader. */
>> +    long long int start_time = 0;
>> +    uint64_t last_reval_seq = 0;
>> +    unsigned int flow_limit = 0;
>> +    size_t n_flows = 0;
>>
>>      revalidator->name = xasprintf("revalidator_%u", ovsthread_id_self());
>>      set_subprogram_name("%s", revalidator->name);
>>      for (;;) {
>> -        struct list udumps = LIST_INITIALIZER(&udumps);
>> -        struct udpif *udpif = revalidator->udpif;
>> -        size_t i;
>> +        if (leader) {
>> +            uint64_t reval_seq;
>>
>> -        ovs_mutex_lock(&revalidator->mutex);
>> -        if (latch_is_set(&udpif->exit_latch)) {
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> -            return NULL;
>> -        }
>> +            reval_seq = seq_read(udpif->reval_seq);
>> +            udpif->need_revalidate = last_reval_seq != reval_seq;
>> +            last_reval_seq = reval_seq;
>>
>> -        if (!revalidator->n_udumps) {
>> -            if (revalidator->dump_seq != seq_read(udpif->dump_seq)) {
>> -                revalidator->dump_seq = seq_read(udpif->dump_seq);
>> -                revalidator_sweep(revalidator);
>> -            } else {
>> -                ovs_mutex_cond_wait(&revalidator->wake_cond,
>> -                                    &revalidator->mutex);
>> +            n_flows = udpif_get_n_flows(udpif);
>> +            udpif->max_n_flows = MAX(n_flows, udpif->max_n_flows);
>> +            udpif->avg_n_flows = (udpif->avg_n_flows + n_flows) / 2;
>> +
>> +            /* Only the leader checks the exit latch to prevent a race
>> where
>> +             * some threads think it's true and exit and others think
>> it's
>> +             * false and block indefinitely on the reval_barrier */
>> +            udpif->reval_exit = latch_is_set(&udpif->exit_latch);
>> +
>> +            start_time = time_msec();
>> +            if (!udpif->reval_exit) {
>> +                dpif_flow_dump_start(&udpif->dump, udpif->dpif);
>>              }
>>          }
>>
>> -        for (i = 0; i < REVALIDATE_MAX_BATCH && revalidator->n_udumps;
>> i++) {
>> -            list_push_back(&udumps,
>> list_pop_front(&revalidator->udumps));
>> -            revalidator->n_udumps--;
>> +        /* Wait for the leader to start the flow dump. */
>> +        xpthread_barrier_wait(&udpif->reval_barrier);
>> +        if (udpif->reval_exit) {
>> +            break;
>>          }
>> +        revalidate(revalidator);
>> +
>> +        /* Wait for all flows to have been dumped before we garbage
>> collect. */
>> +        xpthread_barrier_wait(&udpif->reval_barrier);
>> +        revalidator_sweep(revalidator);
>> +
>> +        /* Wait for all revalidators to finish garbage collection. */
>> +        xpthread_barrier_wait(&udpif->reval_barrier);
>> +
>> +        if (leader) {
>> +            long long int duration;
>> +
>> +            dpif_flow_dump_done(&udpif->dump);
>> +            seq_change(udpif->dump_seq);
>> +
>> +            duration = MAX(time_msec() - start_time, 1);
>> +            atomic_read(&udpif->flow_limit, &flow_limit);
>> +            udpif->dump_duration = duration;
>> +            if (duration > 2000) {
>> +                flow_limit /= duration / 1000;
>> +            } else if (duration > 1300) {
>> +                flow_limit = flow_limit * 3 / 4;
>> +            } else if (duration < 1000 && n_flows > 2000
>> +                       && flow_limit < n_flows * 1000 / duration) {
>> +                flow_limit += 1000;
>> +            }
>> +            flow_limit = MIN(ofproto_flow_limit, MAX(flow_limit, 1000));
>> +            atomic_store(&udpif->flow_limit, flow_limit);
>>
>> -        /* Wake up the flow dumper. */
>> -        xpthread_cond_signal(&revalidator->wake_cond);
>> -        ovs_mutex_unlock(&revalidator->mutex);
>> +            if (duration > 2000) {
>> +                VLOG_INFO("Spent an unreasonably long %lldms dumping
>> flows",
>> +                          duration);
>> +            }
>>
>> -        if (!list_is_empty(&udumps)) {
>> -            revalidate_udumps(revalidator, &udumps);
>> +            poll_timer_wait_until(start_time + MIN(ofproto_max_idle,
>> 500));
>> +            seq_wait(udpif->reval_seq, last_reval_seq);
>> +            latch_wait(&udpif->exit_latch);
>> +            poll_block();
>>          }
>>      }
>>
>> @@ -1287,15 +1190,16 @@ handle_upcalls(struct handler *handler, struct
>> list *upcalls)
>>      }
>>  }
>>
>> +/* Must be called with udpif->ukeys[hash % udpif->n_revalidators].mutex.
>> */
>>  static struct udpif_key *
>> -ukey_lookup(struct revalidator *revalidator, struct udpif_flow_dump
>> *udump)
>> +ukey_lookup__(struct udpif *udpif, const struct nlattr *key, size_t
>> key_len,
>> +              uint32_t hash)
>>  {
>>      struct udpif_key *ukey;
>> +    struct hmap *hmap = &udpif->ukeys[hash % udpif->n_revalidators].hmap;
>>
>> -    HMAP_FOR_EACH_WITH_HASH (ukey, hmap_node, udump->key_hash,
>> -                             &revalidator->ukeys) {
>> -        if (ukey->key_len == udump->key_len
>> -            && !memcmp(ukey->key, udump->key, udump->key_len)) {
>> +    HMAP_FOR_EACH_WITH_HASH (ukey, hmap_node, hash, hmap) {
>> +        if (ukey->key_len == key_len && !memcmp(ukey->key, key,
>> key_len)) {
>>              return ukey;
>>          }
>>      }
>> @@ -1303,40 +1207,88 @@ ukey_lookup(struct revalidator *revalidator,
>> struct udpif_flow_dump *udump)
>>  }
>>
>>  static struct udpif_key *
>> +ukey_lookup(struct udpif *udpif, const struct nlattr *key, size_t
>> key_len,
>> +            uint32_t hash)
>> +{
>> +    struct udpif_key *ukey;
>> +    uint32_t idx = hash % udpif->n_revalidators;
>> +
>> +    ovs_mutex_lock(&udpif->ukeys[idx].mutex);
>> +    ukey = ukey_lookup__(udpif, key, key_len, hash);
>> +    ovs_mutex_unlock(&udpif->ukeys[idx].mutex);
>> +
>> +    return ukey;
>> +}
>> +
>> +static struct udpif_key *
>>  ukey_create(const struct nlattr *key, size_t key_len, long long int used)
>>  {
>>      struct udpif_key *ukey = xmalloc(sizeof *ukey);
>> +    ovs_mutex_init(&ukey->mutex);
>>
>>      ukey->key = (struct nlattr *) &ukey->key_buf;
>>      memcpy(&ukey->key_buf, key, key_len);
>>      ukey->key_len = key_len;
>>
>> +    ovs_mutex_lock(&ukey->mutex);
>>      ukey->mark = false;
>> +    ukey->flow_exists = true;
>>      ukey->created = used ? used : time_msec();
>>      memset(&ukey->stats, 0, sizeof ukey->stats);
>> +    ovs_mutex_unlock(&ukey->mutex);
>>
>>      return ukey;
>>  }
>>
>> +/* Checks for a ukey in 'udpif->ukeys' with the same 'ukey->key' and
>> 'hash',
>> + * and inserts 'ukey' if it does not exist.
>> + *
>> + * Returns true if 'ukey' was inserted into 'udpif->ukeys', false
>> otherwise. */
>> +static bool
>> +udpif_insert_ukey(struct udpif *udpif, struct udpif_key *ukey, uint32_t
>> hash)
>> +{
>> +    struct udpif_key *duplicate;
>> +    uint32_t idx = hash % udpif->n_revalidators;
>> +    bool ok;
>> +
>> +    ovs_mutex_lock(&udpif->ukeys[idx].mutex);
>> +    duplicate = ukey_lookup__(udpif, ukey->key, ukey->key_len, hash);
>> +    if (duplicate) {
>> +        ok = false;
>> +    } else {
>> +        hmap_insert(&udpif->ukeys[idx].hmap, &ukey->hmap_node, hash);
>> +        ok = true;
>> +    }
>> +    ovs_mutex_unlock(&udpif->ukeys[idx].mutex);
>> +
>> +    return ok;
>> +}
>> +
>>  static void
>>  ukey_delete(struct revalidator *revalidator, struct udpif_key *ukey)
>>  {
>> -    hmap_remove(&revalidator->ukeys, &ukey->hmap_node);
>> +    if (revalidator) {
>> +        hmap_remove(revalidator->ukeys, &ukey->hmap_node);
>> +    }
>> +    ovs_mutex_destroy(&ukey->mutex);
>>      free(ukey);
>>  }
>>
>> -static bool
>> -revalidate_ukey(struct udpif *udpif, struct udpif_flow_dump *udump,
>> -                struct udpif_key *ukey)
>> +    static bool
>> +revalidate_ukey(struct udpif *udpif, struct udpif_key *ukey,
>> +                const struct nlattr *mask, size_t mask_len,
>> +                const struct nlattr *actions, size_t actions_len,
>> +                const struct dpif_flow_stats *stats)
>> +
>>  {
>> -    struct ofpbuf xout_actions, *actions;
>>      uint64_t slow_path_buf[128 / 8];
>>      struct xlate_out xout, *xoutp;
>>      struct netflow *netflow;
>> -    struct flow flow, udump_mask;
>>      struct ofproto_dpif *ofproto;
>>      struct dpif_flow_stats push;
>> -    uint32_t *udump32, *xout32;
>> +    struct ofpbuf xout_actions;
>> +    struct flow flow, dp_mask;
>> +    uint32_t *dp32, *xout32;
>>      odp_port_t odp_in_port;
>>      struct xlate_in xin;
>>      int error;
>> @@ -1345,30 +1297,21 @@ revalidate_ukey(struct udpif *udpif, struct
>> udpif_flow_dump *udump,
>>
>>      ok = false;
>>      xoutp = NULL;
>> -    actions = NULL;
>>      netflow = NULL;
>>
>> -    /* If we don't need to revalidate, we can simply push the stats
>> contained
>> -     * in the udump, otherwise we'll have to get the actions so we can
>> check
>> -     * them. */
>> -    if (udump->need_revalidate) {
>> -        if (dpif_flow_get(udpif->dpif, ukey->key, ukey->key_len,
>> &actions,
>> -                          &udump->stats)) {
>> -            goto exit;
>> -        }
>> -    }
>> -
>> -    push.used = udump->stats.used;
>> -    push.tcp_flags = udump->stats.tcp_flags;
>> -    push.n_packets = udump->stats.n_packets > ukey->stats.n_packets
>> -        ? udump->stats.n_packets - ukey->stats.n_packets
>> +    ovs_mutex_lock(&ukey->mutex);
>> +    push.used = stats->used;
>> +    push.tcp_flags = stats->tcp_flags;
>> +    push.n_packets = stats->n_packets > ukey->stats.n_packets
>> +        ? stats->n_packets - ukey->stats.n_packets
>>          : 0;
>> -    push.n_bytes = udump->stats.n_bytes > ukey->stats.n_bytes
>> -        ? udump->stats.n_bytes - ukey->stats.n_bytes
>> +    push.n_bytes = stats->n_bytes > ukey->stats.n_bytes
>> +        ? stats->n_bytes - ukey->stats.n_bytes
>>          : 0;
>> -    ukey->stats = udump->stats;
>> +    ukey->stats = *stats;
>> +    ovs_mutex_unlock(&ukey->mutex);
>>
>> -    if (!push.n_packets && !udump->need_revalidate) {
>> +    if (!push.n_packets && !udpif->need_revalidate) {
>>          ok = true;
>>          goto exit;
>>      }
>> @@ -1382,11 +1325,11 @@ revalidate_ukey(struct udpif *udpif, struct
>> udpif_flow_dump *udump,
>>      xlate_in_init(&xin, ofproto, &flow, NULL, push.tcp_flags, NULL);
>>      xin.resubmit_stats = push.n_packets ? &push : NULL;
>>      xin.may_learn = push.n_packets > 0;
>> -    xin.skip_wildcards = !udump->need_revalidate;
>> +    xin.skip_wildcards = !udpif->need_revalidate;
>>      xlate_actions(&xin, &xout);
>>      xoutp = &xout;
>>
>> -    if (!udump->need_revalidate) {
>> +    if (!udpif->need_revalidate) {
>>          ok = true;
>>          goto exit;
>>      }
>> @@ -1399,11 +1342,12 @@ revalidate_ukey(struct udpif *udpif, struct
>> udpif_flow_dump *udump,
>>          compose_slow_path(udpif, &xout, odp_in_port, &xout_actions);
>>      }
>>
>> -    if (!ofpbuf_equal(&xout_actions, actions)) {
>> +    if (actions_len != xout_actions.size
>> +        || memcmp(xout_actions.data, actions, actions_len)) {
>>          goto exit;
>>      }
>>
>> -    if (odp_flow_key_to_mask(udump->mask, udump->mask_len, &udump_mask,
>> &flow)
>> +    if (odp_flow_key_to_mask(mask, mask_len, &dp_mask, &flow)
>>          == ODP_FIT_ERROR) {
>>          goto exit;
>>      }
>> @@ -1413,10 +1357,10 @@ revalidate_ukey(struct udpif *udpif, struct
>> udpif_flow_dump *udump,
>>       * mask in the kernel is more specific i.e. less wildcarded, than
>> what
>>       * we've calculated here.  This guarantees we don't catch any
>> packets we
>>       * shouldn't with the megaflow. */
>> -    udump32 = (uint32_t *) &udump_mask;
>> +    dp32 = (uint32_t *) &dp_mask;
>>      xout32 = (uint32_t *) &xout.wc.masks;
>>      for (i = 0; i < FLOW_U32S; i++) {
>> -        if ((udump32[i] | xout32[i]) != udump32[i]) {
>> +        if ((dp32[i] | xout32[i]) != dp32[i]) {
>>              goto exit;
>>          }
>>      }
>> @@ -1430,24 +1374,21 @@ exit:
>>          }
>>          netflow_unref(netflow);
>>      }
>> -    ofpbuf_delete(actions);
>>      xlate_out_uninit(xoutp);
>>      return ok;
>>  }
>>
>>  struct dump_op {
>>      struct udpif_key *ukey;
>> -    struct udpif_flow_dump *udump;
>>      struct dpif_flow_stats stats; /* Stats for 'op'. */
>>      struct dpif_op op;            /* Flow del operation. */
>>  };
>>
>>  static void
>>  dump_op_init(struct dump_op *op, const struct nlattr *key, size_t
>> key_len,
>> -             struct udpif_key *ukey, struct udpif_flow_dump *udump)
>> +             struct udpif_key *ukey)
>>  {
>>      op->ukey = ukey;
>> -    op->udump = udump;
>>      op->op.type = DPIF_OP_FLOW_DEL;
>>      op->op.u.flow_del.key = key;
>>      op->op.u.flow_del.key_len = key_len;
>> @@ -1455,10 +1396,8 @@ dump_op_init(struct dump_op *op, const struct
>> nlattr *key, size_t key_len,
>>  }
>>
>>  static void
>> -push_dump_ops(struct revalidator *revalidator,
>> -              struct dump_op *ops, size_t n_ops)
>> +push_dump_ops__(struct udpif *udpif, struct dump_op *ops, size_t n_ops)
>>  {
>> -    struct udpif *udpif = revalidator->udpif;
>>      struct dpif_op *opsp[REVALIDATE_MAX_BATCH];
>>      size_t i;
>>
>> @@ -1475,10 +1414,12 @@ push_dump_ops(struct revalidator *revalidator,
>>          stats = op->op.u.flow_del.stats;
>>          if (op->ukey) {
>>              push = &push_buf;
>> +            ovs_mutex_lock(&op->ukey->mutex);
>>              push->used = MAX(stats->used, op->ukey->stats.used);
>>              push->tcp_flags = stats->tcp_flags |
>> op->ukey->stats.tcp_flags;
>>              push->n_packets = stats->n_packets -
>> op->ukey->stats.n_packets;
>>              push->n_bytes = stats->n_bytes - op->ukey->stats.n_bytes;
>> +            ovs_mutex_unlock(&op->ukey->mutex);
>>          } else {
>>              push = stats;
>>          }
>> @@ -1508,94 +1449,120 @@ push_dump_ops(struct revalidator *revalidator,
>>              }
>>          }
>>      }
>> +}
>>
>> -    for (i = 0; i < n_ops; i++) {
>> -        struct udpif_key *ukey;
>> +static void
>> +push_dump_ops(struct revalidator *revalidator,
>> +              struct dump_op *ops, size_t n_ops)
>> +{
>> +    int i;
>>
>> -        /* If there's a udump, this ukey came directly from a datapath
>> flow
>> -         * dump.  Sometimes a datapath can send duplicates in flow
>> dumps, in
>> -         * which case we wouldn't want to double-free a ukey, so avoid
>> that by
>> -         * looking up the ukey again.
>> -         *
>> -         * If there's no udump then we know what we're doing. */
>> -        ukey = (ops[i].udump
>> -                ? ukey_lookup(revalidator, ops[i].udump)
>> -                : ops[i].ukey);
>> -        if (ukey) {
>> -            ukey_delete(revalidator, ukey);
>> -        }
>> +    push_dump_ops__(revalidator->udpif, ops, n_ops);
>> +    for (i = 0; i < n_ops; i++) {
>> +        ukey_delete(revalidator, ops[i].ukey);
>>      }
>>  }
>>
>>  static void
>> -revalidate_udumps(struct revalidator *revalidator, struct list *udumps)
>> +revalidate(struct revalidator *revalidator)
>>  {
>>      struct udpif *udpif = revalidator->udpif;
>>
>>      struct dump_op ops[REVALIDATE_MAX_BATCH];
>> -    struct udpif_flow_dump *udump, *next_udump;
>> -    size_t n_ops, n_flows;
>> +    const struct nlattr *key, *mask, *actions;
>> +    size_t key_len, mask_len, actions_len;
>> +    const struct dpif_flow_stats *stats;
>> +    long long int now;
>>      unsigned int flow_limit;
>> -    long long int max_idle;
>> -    bool must_del;
>> +    size_t n_ops;
>> +    void *state;
>>
>> +    n_ops = 0;
>> +    now = time_msec();
>>      atomic_read(&udpif->flow_limit, &flow_limit);
>>
>> -    n_flows = udpif_get_n_flows(udpif);
>> -
>> -    must_del = false;
>> -    max_idle = ofproto_max_idle;
>> -    if (n_flows > flow_limit) {
>> -        must_del = n_flows > 2 * flow_limit;
>> -        max_idle = 100;
>> -    }
>> -
>> -    n_ops = 0;
>> -    LIST_FOR_EACH_SAFE (udump, next_udump, list_node, udumps) {
>> -        long long int used, now;
>> +    dpif_flow_dump_state_init(udpif->dpif, &state);
>> +    while (dpif_flow_dump_next(&udpif->dump, state, &key, &key_len,
>> &mask,
>> +                               &mask_len, &actions, &actions_len,
>> &stats)) {
>>          struct udpif_key *ukey;
>> +        bool mark, may_destroy;
>> +        long long int used, max_idle;
>> +        uint32_t hash;
>> +        size_t n_flows;
>>
>> -        now = time_msec();
>> -        ukey = ukey_lookup(revalidator, udump);
>> +        hash = hash_bytes(key, key_len, udpif->secret);
>> +        ukey = ukey_lookup(udpif, key, key_len, hash);
>>
>> -        used = udump->stats.used;
>> +        used = stats->used;
>>          if (!used && ukey) {
>> +            ovs_mutex_lock(&ukey->mutex);
>>              used = ukey->created;
>> +            ovs_mutex_unlock(&ukey->mutex);
>>          }
>>
>> -        if (must_del || (used && used < now - max_idle)) {
>> -            struct dump_op *dop = &ops[n_ops++];
>> +        n_flows = udpif_get_n_flows(udpif);
>> +        max_idle = ofproto_max_idle;
>> +        if (n_flows > flow_limit) {
>> +            max_idle = 100;
>> +        }
>>
>> -            dump_op_init(dop, udump->key, udump->key_len, ukey, udump);
>> -            continue;
>> +        if ((used && used < now - max_idle) || n_flows > flow_limit * 2)
>> {
>> +            mark = false;
>> +        } else {
>> +            if (!ukey) {
>> +                ukey = ukey_create(key, key_len, used);
>> +                if (!udpif_insert_ukey(udpif, ukey, hash)) {
>> +                    /* The same ukey has already been created. This
>> means that
>> +                     * another revalidator is processing this flow
>> +                     * concurrently, so don't bother processing it. */
>> +                    ukey_delete(NULL, ukey);
>> +                    continue;
>> +                }
>> +            }
>> +
>> +            mark = revalidate_ukey(udpif, ukey, mask, mask_len, actions,
>> +                                   actions_len, stats);
>> +        }
>> +
>> +        if (ukey) {
>> +            ovs_mutex_lock(&ukey->mutex);
>> +            ukey->mark = ukey->flow_exists = mark;
>> +            ovs_mutex_unlock(&ukey->mutex);
>>          }
>>
>> -        if (!ukey) {
>> -            ukey = ukey_create(udump->key, udump->key_len, used);
>> -            hmap_insert(&revalidator->ukeys, &ukey->hmap_node,
>> -                        udump->key_hash);
>> +        if (!mark) {
>> +            dump_op_init(&ops[n_ops++], key, key_len, ukey);
>>          }
>> -        ukey->mark = true;
>>
>> -        if (!revalidate_ukey(udpif, udump, ukey)) {
>> -            dpif_flow_del(udpif->dpif, udump->key, udump->key_len, NULL);
>> -            ukey_delete(revalidator, ukey);
>> +        may_destroy = dpif_flow_dump_next_may_destroy_keys(&udpif->dump,
>> +                                                           state);
>> +
>> +        /* Only update 'now' immediately before 'buffer' will be updated.
>> +         * This gives us the current time relative to the time the
>> datapath
>> +         * will write into 'stats'. */
>> +        if (may_destroy) {
>> +            now = time_msec();
>>          }
>>
>> -        list_remove(&udump->list_node);
>> -        free(udump);
>> +        /* Only do a dpif_operate when we've hit our maximum batch, or
>> when our
>> +         * memory is about to be clobbered by the next call to
>> +         * dpif_flow_dump_next(). */
>> +        if (n_ops == REVALIDATE_MAX_BATCH || (n_ops && may_destroy)) {
>> +            push_dump_ops__(udpif, ops, n_ops);
>> +            n_ops = 0;
>> +        }
>>      }
>>
>> -    push_dump_ops(revalidator, ops, n_ops);
>> -
>> -    LIST_FOR_EACH_SAFE (udump, next_udump, list_node, udumps) {
>> -        list_remove(&udump->list_node);
>> -        free(udump);
>> +    if (n_ops) {
>> +        push_dump_ops__(udpif, ops, n_ops);
>>      }
>> +
>> +    dpif_flow_dump_state_uninit(udpif->dpif, state);
>>  }
>>
>>  static void
>>  revalidator_sweep__(struct revalidator *revalidator, bool purge)
>> +    OVS_NO_THREAD_SAFETY_ANALYSIS
>>  {
>>      struct dump_op ops[REVALIDATE_MAX_BATCH];
>>      struct udpif_key *ukey, *next;
>> @@ -1603,16 +1570,20 @@ revalidator_sweep__(struct revalidator
>> *revalidator, bool purge)
>>
>>      n_ops = 0;
>>
>> -    HMAP_FOR_EACH_SAFE (ukey, next, hmap_node, &revalidator->ukeys) {
>> +    /* During garbage collection, this revalidator completely owns its
>> ukeys
>> +     * map, and therefore doesn't need to do any locking. */
>> +    HMAP_FOR_EACH_SAFE (ukey, next, hmap_node, revalidator->ukeys) {
>>          if (!purge && ukey->mark) {
>>              ukey->mark = false;
>> +        } else if (!ukey->flow_exists) {
>> +            ukey_delete(revalidator, ukey);
>>          } else {
>>              struct dump_op *op = &ops[n_ops++];
>>
>>              /* If we have previously seen a flow in the datapath, but
>> didn't
>>               * see it during the most recent dump, delete it. This
>> allows us
>>               * to clean up the ukey and keep the statistics consistent.
>> */
>> -            dump_op_init(op, ukey->key, ukey->key_len, ukey, NULL);
>> +            dump_op_init(op, ukey->key, ukey->key_len, ukey);
>>              if (n_ops == REVALIDATE_MAX_BATCH) {
>>                  push_dump_ops(revalidator, ops, n_ops);
>>                  n_ops = 0;
>> @@ -1670,13 +1641,10 @@ upcall_unixctl_show(struct unixctl_conn *conn,
>> int argc OVS_UNUSED,
>>          for (i = 0; i < n_revalidators; i++) {
>>              struct revalidator *revalidator = &udpif->revalidators[i];
>>
>> -            /* XXX: The result of hmap_count(&revalidator->ukeys) may
>> not be
>> -             * accurate because it's not protected by the revalidator
>> mutex. */
>> -            ovs_mutex_lock(&revalidator->mutex);
>> -            ds_put_format(&ds, "\t%s: (dump queue %"PRIuSIZE") (keys
>> %"PRIuSIZE
>> -                          ")\n", revalidator->name,
>> revalidator->n_udumps,
>> -                          hmap_count(&revalidator->ukeys));
>> -            ovs_mutex_unlock(&revalidator->mutex);
>> +            ovs_mutex_lock(&udpif->ukeys[i].mutex);
>> +            ds_put_format(&ds, "\t%s: (keys %"PRIuSIZE")\n",
>> revalidator->name,
>> +                          hmap_count(&udpif->ukeys[i].hmap));
>> +            ovs_mutex_unlock(&udpif->ukeys[i].mutex);
>>          }
>>      }
>>
>> --
>> 1.7.10.4
>>
>>
>>
>
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