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>
diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
index a97c567..9c723ec 100644
--- a/Documentation/networking/bonding.txt
+++ b/Documentation/networking/bonding.txt
@@ -585,13 +585,19 @@
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 @@
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