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: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
index dc3893841752..9fba7a1e6d51 100644
--- a/drivers/net/bonding/bond_options.c
+++ b/drivers/net/bonding/bond_options.c
@@ -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;
+}