On Sat, Apr 18, 2020 at 10:25 AM <xiangxia.m....@gmail.com> wrote: > > From: Tonghao Zhang <xiangxia.m....@gmail.com> > > In kernel datapath of Open vSwitch, there are only 1024 > buckets of meter in one dp. If installing more than 1024 > (e.g. 8192) meters, it may lead to the performance drop. > But in some case, for example, Open vSwitch used as edge > gateway, there should be 200,000+ at least, meters used for > IP address bandwidth limitation. > > [Open vSwitch userspace datapath has this issue too.] > > For more scalable meter, this patch expands the buckets > when necessary, so we can install more meters in the datapath. > Introducing the struct *dp_meter_instance*, it's easy to > expand meter though changing the *ti* point in the struct > *dp_meter_table*. > > Cc: Pravin B Shelar <pshe...@ovn.org> > Cc: Andy Zhou <az...@ovn.org> > Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com> > --- > net/openvswitch/datapath.h | 2 +- > net/openvswitch/meter.c | 200 +++++++++++++++++++++++++++++-------- > net/openvswitch/meter.h | 15 ++- > 3 files changed, 169 insertions(+), 48 deletions(-) > > diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h > index e239a46c2f94..785105578448 100644 > --- a/net/openvswitch/datapath.h > +++ b/net/openvswitch/datapath.h > @@ -82,7 +82,7 @@ struct datapath { > u32 max_headroom; > > /* Switch meters. */ > - struct hlist_head *meters; > + struct dp_meter_table *meters; lets define it as part of this struct to avoid indirection.
> }; > > /** > diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c > index 5010d1ddd4bd..494a0014ecd8 100644 > --- a/net/openvswitch/meter.c > +++ b/net/openvswitch/meter.c > @@ -19,8 +19,6 @@ > #include "datapath.h" > #include "meter.h" > > -#define METER_HASH_BUCKETS 1024 > - > static const struct nla_policy meter_policy[OVS_METER_ATTR_MAX + 1] = { > [OVS_METER_ATTR_ID] = { .type = NLA_U32, }, > [OVS_METER_ATTR_KBPS] = { .type = NLA_FLAG }, > @@ -39,6 +37,11 @@ static const struct nla_policy > band_policy[OVS_BAND_ATTR_MAX + 1] = { > [OVS_BAND_ATTR_STATS] = { .len = sizeof(struct ovs_flow_stats) }, > }; > > +static u32 meter_hash(struct dp_meter_instance *ti, u32 id) > +{ > + return id % ti->n_meters; > +} > + > static void ovs_meter_free(struct dp_meter *meter) > { > if (!meter) > @@ -47,40 +50,141 @@ static void ovs_meter_free(struct dp_meter *meter) > kfree_rcu(meter, rcu); > } > > -static struct hlist_head *meter_hash_bucket(const struct datapath *dp, > - u32 meter_id) > -{ > - return &dp->meters[meter_id & (METER_HASH_BUCKETS - 1)]; > -} > - > /* Call with ovs_mutex or RCU read lock. */ > -static struct dp_meter *lookup_meter(const struct datapath *dp, > +static struct dp_meter *lookup_meter(const struct dp_meter_table *tbl, > u32 meter_id) > { > + struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti); > + u32 hash = meter_hash(ti, meter_id); > struct dp_meter *meter; > - struct hlist_head *head; > > - head = meter_hash_bucket(dp, meter_id); > - hlist_for_each_entry_rcu(meter, head, dp_hash_node, > - lockdep_ovsl_is_held()) { > - if (meter->id == meter_id) > - return meter; > - } > + meter = rcu_dereference_ovsl(ti->dp_meters[hash]); > + if (meter && likely(meter->id == meter_id)) > + return meter; > + > return NULL; > } > > -static void attach_meter(struct datapath *dp, struct dp_meter *meter) > +static struct dp_meter_instance *dp_meter_instance_alloc(const u32 size) > +{ > + struct dp_meter_instance *ti; > + > + ti = kvzalloc(sizeof(*ti) + > + sizeof(struct dp_meter *) * size, > + GFP_KERNEL); > + if (!ti) > + return NULL; Given this is a kernel space array we need to have hard limit inplace. > + > + ti->n_meters = size; > + > + return ti; > +} > + > +static void dp_meter_instance_free(struct dp_meter_instance *ti) > +{ > + kvfree(ti); > +} > + > +static void dp_meter_instance_free_rcu(struct rcu_head *rcu) > +{ > + struct dp_meter_instance *ti; > + > + ti = container_of(rcu, struct dp_meter_instance, rcu); > + kvfree(ti); > +} > + > +static int > +dp_meter_instance_realloc(struct dp_meter_table *tbl, u32 size) > +{ > + struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti); > + int n_meters = min(size, ti->n_meters); > + struct dp_meter_instance *new_ti; > + int i; > + > + new_ti = dp_meter_instance_alloc(size); > + if (!new_ti) > + return -ENOMEM; > + > + for (i = 0; i < n_meters; i++) > + new_ti->dp_meters[i] = > + rcu_dereference_ovsl(ti->dp_meters[i]); > + > + rcu_assign_pointer(tbl->ti, new_ti); > + call_rcu(&ti->rcu, dp_meter_instance_free_rcu); > + > + return 0; > +} > + > +static void dp_meter_instance_insert(struct dp_meter_instance *ti, > + struct dp_meter *meter) > +{ > + u32 hash; > + > + hash = meter_hash(ti, meter->id); > + rcu_assign_pointer(ti->dp_meters[hash], meter); > +} > + > +static void dp_meter_instance_remove(struct dp_meter_instance *ti, > + struct dp_meter *meter) > { > - struct hlist_head *head = meter_hash_bucket(dp, meter->id); > + u32 hash; > > - hlist_add_head_rcu(&meter->dp_hash_node, head); > + hash = meter_hash(ti, meter->id); > + RCU_INIT_POINTER(ti->dp_meters[hash], NULL); > } > > -static void detach_meter(struct dp_meter *meter) > +static int attach_meter(struct dp_meter_table *tbl, struct dp_meter *meter) > { > + struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti); > + u32 hash = meter_hash(ti, meter->id); > + > + /* > + * In generally, slot selected should be empty, because > + * OvS uses id-pool to fetch a available id. > + */ > + if (unlikely(rcu_dereference_ovsl(ti->dp_meters[hash]))) > + return -EINVAL; we could return -EBUSY instead. > + > + dp_meter_instance_insert(ti, meter); > + > + /* That function is thread-safe. */ > + if (++tbl->count >= ti->n_meters) > + if (dp_meter_instance_realloc(tbl, ti->n_meters * 2)) > + goto expand_err; > + > + return 0; > + > +expand_err: > + dp_meter_instance_remove(ti, meter); > + tbl->count--; > + return -ENOMEM; > +} > + > +static void detach_meter(struct dp_meter_table *tbl, struct dp_meter *meter) > +{ > + struct dp_meter_instance *ti; > + > ASSERT_OVSL(); > - if (meter) > - hlist_del_rcu(&meter->dp_hash_node); > + if (!meter) > + return; > + > + ti = rcu_dereference_ovsl(tbl->ti); > + dp_meter_instance_remove(ti, meter); > + > + tbl->count--; > + > + /* Shrink the meter array if necessary. */ > + if (ti->n_meters > DP_METER_ARRAY_SIZE_MIN && > + tbl->count <= (ti->n_meters / 4)) { > + int half_size = ti->n_meters / 2; > + int i; > + Lets add a comment about this. > + for (i = half_size; i < ti->n_meters; i++) > + if (rcu_dereference_ovsl(ti->dp_meters[i])) > + return; > + > + dp_meter_instance_realloc(tbl, half_size); > + } > } > > static struct sk_buff * > @@ -303,9 +407,13 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct > genl_info *info) > meter_id = nla_get_u32(a[OVS_METER_ATTR_ID]); > > /* Cannot fail after this. */ > - old_meter = lookup_meter(dp, meter_id); > - detach_meter(old_meter); > - attach_meter(dp, meter); > + old_meter = lookup_meter(dp->meters, meter_id); in new scheme this can fail due to hash collision, lets check for NULL. > + detach_meter(dp->meters, old_meter); > + > + err = attach_meter(dp->meters, meter); > + if (err) > + goto exit_unlock; > + > ovs_unlock(); > > /* Build response with the meter_id and stats from > @@ -365,7 +473,7 @@ static int ovs_meter_cmd_get(struct sk_buff *skb, struct > genl_info *info) > } > > /* Locate meter, copy stats. */ > - meter = lookup_meter(dp, meter_id); > + meter = lookup_meter(dp->meters, meter_id); > if (!meter) { > err = -ENOENT; > goto exit_unlock; > @@ -416,13 +524,13 @@ static int ovs_meter_cmd_del(struct sk_buff *skb, > struct genl_info *info) > goto exit_unlock; > } > > - old_meter = lookup_meter(dp, meter_id); > + old_meter = lookup_meter(dp->meters, meter_id); > if (old_meter) { > spin_lock_bh(&old_meter->lock); > err = ovs_meter_cmd_reply_stats(reply, meter_id, old_meter); > WARN_ON(err); > spin_unlock_bh(&old_meter->lock); > - detach_meter(old_meter); > + detach_meter(dp->meters, old_meter); > } > ovs_unlock(); > ovs_meter_free(old_meter); > @@ -452,7 +560,7 @@ bool ovs_meter_execute(struct datapath *dp, struct > sk_buff *skb, > int i, band_exceeded_max = -1; > u32 band_exceeded_rate = 0; > > - meter = lookup_meter(dp, meter_id); > + meter = lookup_meter(dp->meters, meter_id); > /* Do not drop the packet when there is no meter. */ > if (!meter) > return false; > @@ -570,32 +678,36 @@ struct genl_family dp_meter_genl_family __ro_after_init > = { > > int ovs_meters_init(struct datapath *dp) > { > - int i; > + struct dp_meter_instance *ti; > + struct dp_meter_table *tbl; > + > + tbl = kmalloc(sizeof(*tbl), GFP_KERNEL); > + if (!tbl) > + return -ENOMEM; > > - dp->meters = kmalloc_array(METER_HASH_BUCKETS, > - sizeof(struct hlist_head), GFP_KERNEL); > + tbl->count = 0; > > - if (!dp->meters) > + ti = dp_meter_instance_alloc(DP_METER_ARRAY_SIZE_MIN); > + if (!ti) { > + kfree(tbl); > return -ENOMEM; > + } > > - for (i = 0; i < METER_HASH_BUCKETS; i++) > - INIT_HLIST_HEAD(&dp->meters[i]); > + rcu_assign_pointer(tbl->ti, ti); > + dp->meters = tbl; > > return 0; > } > > void ovs_meters_exit(struct datapath *dp) > { > + struct dp_meter_table *tbl = dp->meters; > + struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti); > int i; > > - for (i = 0; i < METER_HASH_BUCKETS; i++) { > - struct hlist_head *head = &dp->meters[i]; > - struct dp_meter *meter; > - struct hlist_node *n; > - > - hlist_for_each_entry_safe(meter, n, head, dp_hash_node) > - kfree(meter); > - } > + for (i = 0; i < ti->n_meters; i++) > + ovs_meter_free(ti->dp_meters[i]); > > - kfree(dp->meters); > + dp_meter_instance_free(ti); > + kfree(tbl); > } > diff --git a/net/openvswitch/meter.h b/net/openvswitch/meter.h > index f645913870bd..d91940383bbe 100644 > --- a/net/openvswitch/meter.h > +++ b/net/openvswitch/meter.h > @@ -18,6 +18,7 @@ > struct datapath; > > #define DP_MAX_BANDS 1 > +#define DP_METER_ARRAY_SIZE_MIN (1ULL << 10) > > struct dp_meter_band { > u32 type; > @@ -30,9 +31,6 @@ struct dp_meter_band { > struct dp_meter { > spinlock_t lock; /* Per meter lock */ > struct rcu_head rcu; > - struct hlist_node dp_hash_node; /*Element in datapath->meters > - * hash table. > - */ > u32 id; > u16 kbps:1, keep_stats:1; > u16 n_bands; > @@ -42,6 +40,17 @@ struct dp_meter { > struct dp_meter_band bands[]; > }; > > +struct dp_meter_instance { > + struct rcu_head rcu; > + u32 n_meters; > + struct dp_meter __rcu *dp_meters[]; > +}; > + > +struct dp_meter_table { > + struct dp_meter_instance __rcu *ti; > + u32 count; > +}; > + > extern struct genl_family dp_meter_genl_family; > int ovs_meters_init(struct datapath *dp); > void ovs_meters_exit(struct datapath *dp); > -- > 2.23.0 > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev