Ok, thanks.
On Wed, Apr 1, 2020 at 3:50 AM Tonghao Zhang <xiangxia.m....@gmail.com> wrote: > > On Tue, Mar 31, 2020 at 11:57 AM Pravin Shelar <pshe...@ovn.org> wrote: > > > > On Sun, Mar 29, 2020 at 5:35 PM Tonghao Zhang <xiangxia.m....@gmail.com> > > wrote: > > > > > > On Mon, Mar 30, 2020 at 12:46 AM Pravin Shelar <pshe...@ovn.org> wrote: > > > > > > > > On Sat, Mar 28, 2020 at 8:46 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 change the *ti* point in the struct > > > > > *dp_meter_table*. > > > > > * Using kvmalloc_array instead of kmalloc_array. > > > > > > > > > Thanks for working on this, I have couple of comments. > > > > > > > > > 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 | 168 > > > > > ++++++++++++++++++++++++++++++------- > > > > > net/openvswitch/meter.h | 17 +++- > > > > > 3 files changed, 153 insertions(+), 34 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; > > > > > }; > > > > > > > > > > /** > > > > > diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c > > > > > index 5010d1ddd4bd..98003b201b45 100644 > > > > > --- a/net/openvswitch/meter.c > > > > > +++ b/net/openvswitch/meter.c > > > > > @@ -47,40 +47,136 @@ static void ovs_meter_free(struct dp_meter > > > > > *meter) > > > > > kfree_rcu(meter, rcu); > > > > > } > > > > > > > > > > -static struct hlist_head *meter_hash_bucket(const struct datapath > > > > > *dp, > > > > > +static struct hlist_head *meter_hash_bucket(struct dp_meter_instance > > > > > *ti, > > > > > u32 meter_id) > > > > > { > > > > > - return &dp->meters[meter_id & (METER_HASH_BUCKETS - 1)]; > > > > > + u32 hash = jhash_1word(meter_id, ti->hash_seed); > > > > > + > > > > I do not see any need to hash meter-id, can you explain it. > > > > > > > > > + return &ti->buckets[hash & (ti->n_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); > > > > > 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()) { > > > > > + head = meter_hash_bucket(ti, meter_id); > > > > > + hlist_for_each_entry_rcu(meter, head, hash_node[ti->node_ver], > > > > > + lockdep_ovsl_is_held()) { > > > > > if (meter->id == meter_id) > > > > > return meter; > > > > > } > > > > > + > > > > This patch is expanding meter table linearly with number meters added > > > > to datapath. so I do not see need to have hash table. it can be a > > > > simple array. This would also improve lookup efficiency. > > > > For hash collision we could find next free slot in array. let me know > > > > what do you think about this approach. > > > Hi Pravin > > > If we use the simple array, when inserting the meter, for hash collision, > > > we can > > > find next free slot, but one case, when there are many meters in the > > > array. > > > we may find many slot for the free slot. > > > And when we lookup the meter, for hash collision, we may find many > > > array slots, and > > > then find it, or that meter does not exist in the array, In that case, > > > there may be a lookup performance > > > drop. > > > > > I was thinking that users can insure that there are no hash collision, > > but time complexity of negative case is expensive. so I am fine with > > the hash table. > Hi Pravi > I check again the meter implementation of ovs, ovs-vswitchd use the id-pool to > get a valid meter-id which passed to kernel, so there is no hash collision. > You > are right. we use the single array is the better solution. > > > For hash meter-id in meter_hash_bucket, I am not 100% sure it is > > > useful. it just update > > > hash_seed when expand meters. For performance, we can remove it. Thanks. > > ok. > > > > > > > return NULL; > > > > > } > > > > > > > > > > -static void attach_meter(struct datapath *dp, struct dp_meter *meter) > > > > > +static struct dp_meter_instance *dp_meter_instance_alloc(const int > > > > > size) > > > > > +{ > > > > > + struct dp_meter_instance *ti; > > > > > + int i; > > > > > + > > > > > + ti = kmalloc(sizeof(*ti), GFP_KERNEL); > > > > > + if (!ti) > > > > > + return NULL; > > > > > + > > > > > + ti->buckets = kvmalloc_array(size, sizeof(struct hlist_head), > > > > > + GFP_KERNEL); > > > > > + if (!ti->buckets) { > > > > > + kfree(ti); > > > > > + return NULL; > > > > > + } > > > > > + > > > > > + for (i = 0; i < size; i++) > > > > > + INIT_HLIST_HEAD(&ti->buckets[i]); > > > > > + > > > > > + ti->n_buckets = size; > > > > > + ti->node_ver = 0; > > > > > + get_random_bytes(&ti->hash_seed, sizeof(u32)); > > > > > + > > > > > + return ti; > > > > > +} > > > > > + > > > > > +static void dp_meter_instance_free_rcu(struct rcu_head *rcu) > > > > > { > > > > > - struct hlist_head *head = meter_hash_bucket(dp, meter->id); > > > > > + struct dp_meter_instance *ti; > > > > > > > > > > - hlist_add_head_rcu(&meter->dp_hash_node, head); > > > > > + ti = container_of(rcu, struct dp_meter_instance, rcu); > > > > > + kvfree(ti->buckets); > > > > > + kfree(ti); > > > > > } > > > > > > > > > > -static void detach_meter(struct dp_meter *meter) > > > > > +static void dp_meter_instance_insert(struct dp_meter_instance *ti, > > > > > + struct dp_meter *meter) > > > > > +{ > > > > > + struct hlist_head *head = meter_hash_bucket(ti, meter->id); > > > > > + > > > > > + hlist_add_head_rcu(&meter->hash_node[ti->node_ver], head); > > > > > +} > > > > > + > > > > > +static void dp_meter_instance_remove(struct dp_meter_instance *ti, > > > > > + struct dp_meter *meter) > > > > > { > > > > > + hlist_del_rcu(&meter->hash_node[ti->node_ver]); > > > > > +} > > > > > + > > > > > +static struct dp_meter_instance * > > > > > +dp_meter_instance_expand(struct dp_meter_instance *ti) > > > > > +{ > > > > > + struct dp_meter_instance *new_ti; > > > > > + int i; > > > > > + > > > > > + new_ti = dp_meter_instance_alloc(ti->n_buckets * 2); > > > > > + if (!new_ti) > > > > > + return NULL; > > > > > + > > > > > + new_ti->node_ver = !ti->node_ver; > > > > > + > > > > > + for (i = 0; i < ti->n_buckets; i++) { > > > > > + struct hlist_head *head = &ti->buckets[i]; > > > > > + struct dp_meter *meter; > > > > > + > > > > > + hlist_for_each_entry_rcu(meter, head, > > > > > hash_node[ti->node_ver], > > > > > + lockdep_ovsl_is_held()) > > > > > + dp_meter_instance_insert(new_ti, meter); > > > > > + } > > > > > + > > > > > + return new_ti; > > > > > +} > > > > > + > > > > > +static void attach_meter(struct dp_meter_table *tbl, struct dp_meter > > > > > *meter) > > > > > +{ > > > > > + struct dp_meter_instance *new_ti; > > > > > + struct dp_meter_instance *ti; > > > > > + > > > > > + ti = rcu_dereference_ovsl(tbl->ti); > > > > > + dp_meter_instance_insert(ti, meter); > > > > > + > > > > > + /* operate the counter safely, because called with ovs_lock. > > > > > */ > > > > > + tbl->count++; > > > > > + > > > > > + if (tbl->count > ti->n_buckets) { > > > > > + new_ti = dp_meter_instance_expand(ti); > > > > > + > > > > > > > > > > > > > + if (new_ti) { > > > > > + rcu_assign_pointer(tbl->ti, new_ti); > > > > > + call_rcu(&ti->rcu, > > > > > dp_meter_instance_free_rcu); > > > > > + } > > > > > + } > > > > > +} > > > > > + > > > > > +static void detach_meter(struct dp_meter_table *tbl, struct dp_meter > > > > > *meter) > > > > > +{ > > > > > + struct dp_meter_instance *ti = rcu_dereference_ovsl(tbl->ti); > > > > > + > > > > > ASSERT_OVSL(); > > > > > - if (meter) > > > > > - hlist_del_rcu(&meter->dp_hash_node); > > > > > + if (meter) { > > > > > + /* operate the counter safely, because called with > > > > > ovs_lock. */ > > > > > + tbl->count--; > > > > > + dp_meter_instance_remove(ti, meter); > > > > > + } > > > > > } > > > > > > > > > > static struct sk_buff * > > > > > @@ -303,9 +399,9 @@ 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); > > > > > + detach_meter(dp->meters, old_meter); > > > > > + attach_meter(dp->meters, meter); > > > > > ovs_unlock(); > > > > > > > > > > /* Build response with the meter_id and stats from > > > > > @@ -365,7 +461,7 @@ 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 +512,13 @@ 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 +548,7 @@ 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 +666,44 @@ 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; > > > > > > > > > > - dp->meters = kmalloc_array(METER_HASH_BUCKETS, > > > > > - sizeof(struct hlist_head), > > > > > GFP_KERNEL); > > > > > + tbl = kmalloc(sizeof(*tbl), GFP_KERNEL); > > > > > + if (!tbl) > > > > > + return -ENOMEM; > > > > > > > > > > - if (!dp->meters) > > > > > + tbl->count = 0; > > > > > + > > > > > + ti = dp_meter_instance_alloc(METER_HASH_BUCKETS); > > > > > + 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]; > > > > > + for (i = 0; i < ti->n_buckets; i++) { > > > > > + struct hlist_head *head = &ti->buckets[i]; > > > > > struct dp_meter *meter; > > > > > struct hlist_node *n; > > > > > > > > > > - hlist_for_each_entry_safe(meter, n, head, > > > > > dp_hash_node) > > > > > - kfree(meter); > > > > > + hlist_for_each_entry_safe(meter, n, head, > > > > > + hash_node[ti->node_ver]) > > > > > + ovs_meter_free(meter); > > > > > } > > > > > > > > > > - kfree(dp->meters); > > > > > + kvfree(ti->buckets); > > > > > + kfree(ti); > > > > > + kfree(tbl); > > > > > } > > > > > diff --git a/net/openvswitch/meter.h b/net/openvswitch/meter.h > > > > > index f645913870bd..bc84796d7d4d 100644 > > > > > --- a/net/openvswitch/meter.h > > > > > +++ b/net/openvswitch/meter.h > > > > > @@ -30,9 +30,7 @@ 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. > > > > > - */ > > > > > + struct hlist_node hash_node[2]; > > > > > u32 id; > > > > > u16 kbps:1, keep_stats:1; > > > > > u16 n_bands; > > > > > @@ -42,6 +40,19 @@ struct dp_meter { > > > > > struct dp_meter_band bands[]; > > > > > }; > > > > > > > > > > +struct dp_meter_instance { > > > > > + struct hlist_head *buckets; > > > > > + struct rcu_head rcu; > > > > > + u32 n_buckets; > > > > > + u32 hash_seed; > > > > > + u8 node_ver; > > > > > +}; > > > > > + > > > > > +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 > > > > > > > > > > > > > > > > > -- > > > Best regards, Tonghao > > > > -- > Best regards, Tonghao _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev