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Commit e9f0fb88 authored by Mahesh Bandewar's avatar Mahesh Bandewar Committed by David S. Miller
Browse files

bonding: Add tlb_dynamic_lb parameter for tlb mode 



The aggresive load balancing causes packet re-ordering as active
flows are moved from a slave to another within the group. Sometime
this aggresive lb is not necessary if the preference is for less
re-ordering. This parameter if used with value "0" disables
this dynamic flow shuffling minimizing packet re-ordering. Of course
the side effect is that it has to live with the static load balancing
that the hashing distribution provides. This impact is less severe if
the correct xmit-hashing-policy is used for the tlb setup.

The default value of the parameter is set to "1" mimicing the earlier
behavior.

Ran the netperf test with 200 stream for 1 min between two hosts with
4x1G trunk (xmit-lb mode with xmit-policy L3+4) before and after these
changes. Following was the command used for those 200 instances -

    netperf -t TCP_RR -l 60 -s 5 -H <host> -- -r81920,81920

Transactions per second:
    Before change: 1,367.11
    After  change: 1,470.65

Change-Id: Ie3f75c77282cf602e83a6e833c6eb164e72a0990
Signed-off-by: default avatarMahesh Bandewar <maheshb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f05b42ea

Documentation/networking/bonding.txt

+35 −7
Original line number Diff line number Diff line
@@ -585,13 +585,19 @@ mode 
	balance-tlb or 5



		Adaptive transmit load balancing: channel bonding that

		does not require any special switch support.  The

		outgoing traffic is distributed according to the

		current load (computed relative to the speed) on each

		slave.  Incoming traffic is received by the current

		slave.  If the receiving slave fails, another slave

		takes over the MAC address of the failed receiving

		slave.

		does not require any special switch support.



		In tlb_dynamic_lb=1 mode; the outgoing traffic is

		distributed according to the current load (computed

		relative to the speed) on each slave.



		In tlb_dynamic_lb=0 mode; the load balancing based on

		current load is disabled and the load is distributed

		only using the hash distribution.



		Incoming traffic is received by the current slave.

		If the receiving slave fails, another slave takes over

		the MAC address of the failed receiving slave.



		Prerequisite:
@@ -736,6 +742,28 @@ primary_reselect 


	This option was added for bonding version 3.6.0.



tlb_dynamic_lb



	Specifies if dynamic shuffling of flows is enabled in tlb

	mode. The value has no effect on any other modes.



	The default behavior of tlb mode is to shuffle active flows across

	slaves based on the load in that interval. This gives nice lb

	characteristics but can cause packet reordering. If re-ordering is

	a concern use this variable to disable flow shuffling and rely on

	load balancing provided solely by the hash distribution.

	xmit-hash-policy can be used to select the appropriate hashing for

	the setup.



	The sysfs entry can be used to change the setting per bond device

	and the initial value is derived from the module parameter. The

	sysfs entry is allowed to be changed only if the bond device is

	down.



	The default value is "1" that enables flow shuffling while value "0"

	disables it. This option was added in bonding driver 3.7.1





updelay



	Specifies the time, in milliseconds, to wait before enabling a

drivers/net/bonding/bond_alb.c

+15 −4
Original line number Diff line number Diff line
@@ -1356,6 +1356,7 @@ static int bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond, 
	if (!tx_slave) {

		/* unbalanced or unassigned, send through primary */

		tx_slave = rcu_dereference(bond->curr_active_slave);

		if (bond->params.tlb_dynamic_lb)

			bond_info->unbalanced_load += skb->len;

	}
@@ -1369,7 +1370,7 @@ static int bond_do_alb_xmit(struct sk_buff *skb, struct bonding *bond, 
		goto out;

	}



	if (tx_slave) {

	if (tx_slave && bond->params.tlb_dynamic_lb) {

		_lock_tx_hashtbl(bond);

		__tlb_clear_slave(bond, tx_slave, 0);

		_unlock_tx_hashtbl(bond);
@@ -1399,11 +1400,21 @@ int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev) 
		    /* In case of IPX, it will falback to L2 hash */

		case htons(ETH_P_IPV6):

			hash_index = bond_xmit_hash(bond, skb);

			tx_slave = tlb_choose_channel(bond, hash_index & 0xFF, skb->len);

			if (bond->params.tlb_dynamic_lb) {

				tx_slave = tlb_choose_channel(bond,

							      hash_index & 0xFF,

							      skb->len);

			} else {

				struct list_head *iter;

				int idx = hash_index % bond->slave_cnt;



				bond_for_each_slave_rcu(bond, tx_slave, iter)

					if (--idx < 0)

						break;

			}

			break;

		}

	}



	return bond_do_alb_xmit(skb, bond, tx_slave);

}

drivers/net/bonding/bond_main.c

+3 −1
Original line number Diff line number Diff line
@@ -3096,6 +3096,7 @@ static int bond_open(struct net_device *bond_dev) 
		 */

		if (bond_alb_initialize(bond, (bond->params.mode == BOND_MODE_ALB)))

			return -ENOMEM;

		if (bond->params.tlb_dynamic_lb)

			queue_delayed_work(bond->wq, &bond->alb_work, 0);

	}
@@ -4304,6 +4305,7 @@ static int bond_check_params(struct bond_params *params) 
	params->min_links = min_links;

	params->lp_interval = lp_interval;

	params->packets_per_slave = packets_per_slave;

	params->tlb_dynamic_lb = 1; /* Default value */

	if (packets_per_slave > 0) {

		params->reciprocal_packets_per_slave =

			reciprocal_value(packets_per_slave);

drivers/net/bonding/bond_options.c

+27 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ static int bond_option_mode_set(struct bonding *bond, 
				const struct bond_opt_value *newval);

static int bond_option_slaves_set(struct bonding *bond,

				  const struct bond_opt_value *newval);

static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,

				  const struct bond_opt_value *newval);





static const struct bond_opt_value bond_mode_tbl[] = {
@@ -179,6 +181,12 @@ static const struct bond_opt_value bond_lp_interval_tbl[] = { 
	{ NULL,      -1,      0},

};



static const struct bond_opt_value bond_tlb_dynamic_lb_tbl[] = {

	{ "off", 0,  0},

	{ "on",  1,  BOND_VALFLAG_DEFAULT},

	{ NULL,  -1, 0}

};



static const struct bond_option bond_opts[] = {

	[BOND_OPT_MODE] = {

		.id = BOND_OPT_MODE,
@@ -364,6 +372,15 @@ static const struct bond_option bond_opts[] = { 
		.flags = BOND_OPTFLAG_RAWVAL,

		.set = bond_option_slaves_set

	},

	[BOND_OPT_TLB_DYNAMIC_LB] = {

		.id = BOND_OPT_TLB_DYNAMIC_LB,

		.name = "dynamic_lb",

		.desc = "Enable dynamic flow shuffling",

		.unsuppmodes = BOND_MODE_ALL_EX(BIT(BOND_MODE_TLB)),

		.values = bond_tlb_dynamic_lb_tbl,

		.flags = BOND_OPTFLAG_IFDOWN,

		.set = bond_option_tlb_dynamic_lb_set,

	},

	{ }

};
@@ -1337,3 +1354,13 @@ err_no_cmd: 
	ret = -EPERM;

	goto out;

}



static int bond_option_tlb_dynamic_lb_set(struct bonding *bond,

					  const struct bond_opt_value *newval)

{

	pr_info("%s: Setting dynamic-lb to %s (%llu)\n",

		bond->dev->name, newval->string, newval->value);

	bond->params.tlb_dynamic_lb = newval->value;



	return 0;

}

drivers/net/bonding/bond_options.h

+1 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ enum { 
	BOND_OPT_RESEND_IGMP,

	BOND_OPT_LP_INTERVAL,

	BOND_OPT_SLAVES,

	BOND_OPT_TLB_DYNAMIC_LB,

	BOND_OPT_LAST

};