On 2018-07-18 3:51 PM, Mahesh Bandewar (महेश बंडेवार) wrote:
On Wed, Jul 18, 2018 at 11:49 AM, Jarod Wilson <jarod@xxxxxxxxxx> wrote:
For some time now, if you load the bonding driver and configure bond
parameters via sysfs using minimal config options, such as specifying
nothing but the mode, relying on defaults for everything else, modes
that cannot use arp monitoring (802.3ad, balance-tlb, balance-alb) all
wind up with both arp_interval=0 (as it should be) and miimon=0, which
means the miimon monitor thread never actually runs. This is particularly
problematic for 802.3ad.
For example, from an LNST recipe I've set up:
$ modprobe bonding max_bonds=0"
$ echo "+t_bond0" > /sys/class/net/bonding_masters"
$ ip link set t_bond0 down"
$ echo "802.3ad" > /sys/class/net/t_bond0/bonding/mode"
$ ip link set ens1f1 down"
$ echo "+ens1f1" > /sys/class/net/t_bond0/bonding/slaves"
$ ip link set ens1f0 down"
$ echo "+ens1f0" > /sys/class/net/t_bond0/bonding/slaves"
$ ethtool -i t_bond0"
$ ip link set ens1f1 up"
$ ip link set ens1f0 up"
$ ip link set t_bond0 up"
$ ip addr add 192.168.9.1/24 dev t_bond0"
$ ip addr add 2002::1/64 dev t_bond0"
This bond comes up okay, but things look slightly suspect in
/proc/net/bonding/t_bond0 output:
$ grep -i mii /proc/net/bonding/t_bond0
MII Status: up
MII Polling Interval (ms): 0
MII Status: up
MII Status: up
This doesn't seem correct since the MII interval set is 0. It should
set to 100 by default for this mode. This may be the side effect of
brining up the bond with default more (balance-rr) and then bringing
bond-down before configuring it. You can probably get away by just not
bringing down the bond (step 'set ip link bond0 down) in your recipe
above. But irrespective of that step, this mode needs miimon and
should have been set correctly.
I don't think bringing the bond down matters. We run bond_check_params()
at module load time, and above, it's loaded via 'modprobe bonding
max_bonds=0', with no mode= set, so bond_check_params() sets bond_mode
to BOND_MODE_ROUNDROBIN. When we get down to the miimon checks, we check
for !bond_mode_uses_arp(BOND_MODE_ROUNDROBIN), which ends up false, so
we never drop into the code block that sets miimon to 100, meaning it's
still 0. Then we set up a new bond via sysfs as mode 802.3ad, which goes
through bond_option_mode_set(), which then also does a
bond_mode_uses_arp() check, but doesn't currently DO anything if you
also (correctly) have arp_interval=0, so the bit there that would have
set miimon to 100 also gets skipped. This just makes sure this setup
path does get a reasonable default value if none was set.
--
Jarod Wilson
jarod@xxxxxxxxxx
