Commit d297653d authored by Roopa Prabhu's avatar Roopa Prabhu Committed by David S. Miller
Browse files

rtnetlink: fdb dump: optimize by saving last interface markers 



fdb dumps spanning multiple skb's currently restart from the first
interface again for every skb. This results in unnecessary
iterations on the already visited interfaces and their fdb
entries. In large scale setups, we have seen this to slow
down fdb dumps considerably. On a system with 30k macs we
see fdb dumps spanning across more than 300 skbs.

To fix the problem, this patch replaces the existing single fdb
marker with three markers: netdev hash entries, netdevs and fdb
index to continue where we left off instead of restarting from the
first netdev. This is consistent with link dumps.

In the process of fixing the performance issue, this patch also
re-implements fix done by
commit 472681d5 ("net: ndo_fdb_dump should report -EMSGSIZE to rtnl_fdb_dump")
(with an internal fix from Wilson Kok) in the following ways:
- change ndo_fdb_dump handlers to return error code instead
of the last fdb index
- use cb->args strictly for dump frag markers and not error codes.
This is consistent with other dump functions.

Below results were taken on a system with 1000 netdevs
and 35085 fdb entries:
before patch:
$time bridge fdb show | wc -l
15065

real    1m11.791s
user    0m0.070s
sys 1m8.395s

(existing code does not return all macs)

after patch:
$time bridge fdb show | wc -l
35085

real    0m2.017s
user    0m0.113s
sys 0m1.942s

Signed-off-by: default avatarRoopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: default avatarWilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 66fdd05e

drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c

+4 −3
Original line number Diff line number Diff line
@@ -432,18 +432,19 @@ static int qlcnic_fdb_add(struct ndmsg *ndm, struct nlattr *tb[], 


static int qlcnic_fdb_dump(struct sk_buff *skb, struct netlink_callback *ncb,

			struct net_device *netdev,

			struct net_device *filter_dev, int idx)

			struct net_device *filter_dev, int *idx)

{

	struct qlcnic_adapter *adapter = netdev_priv(netdev);

	int err = 0;



	if (!adapter->fdb_mac_learn)

		return ndo_dflt_fdb_dump(skb, ncb, netdev, filter_dev, idx);



	if ((adapter->flags & QLCNIC_ESWITCH_ENABLED) ||

	    qlcnic_sriov_check(adapter))

		idx = ndo_dflt_fdb_dump(skb, ncb, netdev, filter_dev, idx);

		err = ndo_dflt_fdb_dump(skb, ncb, netdev, filter_dev, idx);



	return idx;

	return err;

}



static void qlcnic_82xx_cancel_idc_work(struct qlcnic_adapter *adapter)

drivers/net/vxlan.c

+6 −8
Original line number Diff line number Diff line
@@ -860,20 +860,20 @@ out: 
/* Dump forwarding table */

static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,

			  struct net_device *dev,

			  struct net_device *filter_dev, int idx)

			  struct net_device *filter_dev, int *idx)

{

	struct vxlan_dev *vxlan = netdev_priv(dev);

	unsigned int h;

	int err = 0;



	for (h = 0; h < FDB_HASH_SIZE; ++h) {

		struct vxlan_fdb *f;

		int err;



		hlist_for_each_entry_rcu(f, &vxlan->fdb_head[h], hlist) {

			struct vxlan_rdst *rd;



			list_for_each_entry_rcu(rd, &f->remotes, list) {

				if (idx < cb->args[0])

				if (*idx < cb->args[2])

					goto skip;



				err = vxlan_fdb_info(skb, vxlan, f,
@@ -881,17 +881,15 @@ static int vxlan_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb, 
						     cb->nlh->nlmsg_seq,

						     RTM_NEWNEIGH,

						     NLM_F_MULTI, rd);

				if (err < 0) {

					cb->args[1] = err;

				if (err < 0)

					goto out;

				}

skip:

				++idx;

				*idx += 1;

			}

		}

	}

out:

	return idx;

	return err;

}



/* Watch incoming packets to learn mapping between Ethernet address

include/linux/netdevice.h

+2 −2
Original line number Diff line number Diff line
@@ -1031,7 +1031,7 @@ struct netdev_xdp { 
 *	Deletes the FDB entry from dev coresponding to addr.

 * int (*ndo_fdb_dump)(struct sk_buff *skb, struct netlink_callback *cb,

 *		       struct net_device *dev, struct net_device *filter_dev,

 *		       int idx)

 *		       int *idx)

 *	Used to add FDB entries to dump requests. Implementers should add

 *	entries to skb and update idx with the number of entries.

 *
@@ -1263,7 +1263,7 @@ struct net_device_ops { 
						struct netlink_callback *cb,

						struct net_device *dev,

						struct net_device *filter_dev,

						int idx);

						int *idx);



	int			(*ndo_bridge_setlink)(struct net_device *dev,

						      struct nlmsghdr *nlh,

include/linux/rtnetlink.h

+1 −1
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ extern int ndo_dflt_fdb_dump(struct sk_buff *skb, 
			     struct netlink_callback *cb,

			     struct net_device *dev,

			     struct net_device *filter_dev,

			     int idx);

			     int *idx);

extern int ndo_dflt_fdb_add(struct ndmsg *ndm,

			    struct nlattr *tb[],

			    struct net_device *dev,

include/net/switchdev.h

+2 −2
Original line number Diff line number Diff line
@@ -222,7 +222,7 @@ int switchdev_port_fdb_del(struct ndmsg *ndm, struct nlattr *tb[], 
			   u16 vid);

int switchdev_port_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb,

			    struct net_device *dev,

			    struct net_device *filter_dev, int idx);

			    struct net_device *filter_dev, int *idx);

void switchdev_port_fwd_mark_set(struct net_device *dev,

				 struct net_device *group_dev,

				 bool joining);
@@ -342,7 +342,7 @@ static inline int switchdev_port_fdb_dump(struct sk_buff *skb, 
					  struct netlink_callback *cb,

					  struct net_device *dev,

					  struct net_device *filter_dev,

					  int idx)

					  int *idx)

{

       return idx;

}

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