The source of most of the slow down is the `dev_addr_lists.c` module,
which mainatins a linked list of HW addresses.
When using IPv6, this list grows for each IPv6 address added on a
VLAN, since each IPv6 address has a multicast HW address associated with
it.
When performing any modification to the involved links, this list is
traversed many times, often for nothing, all while holding the RTNL
lock.
Instead, this patch adds an auxilliary rbtree which cuts down
traversal time significantly.
Performance can be seen with the following script:
#!/bin/bash
ip netns del test || true 2>/dev/null
ip netns add test
echo 1 | ip netns exec test tee /proc/sys/net/ipv6/conf/all/keep_addr_on_down > /dev/null
set -e
ip -n test link add foo type veth peer name bar
ip -n test link add b1 type bond
ip -n test link add florp type vrf table 10
ip -n test link set bar master b1
ip -n test link set foo up
ip -n test link set bar up
ip -n test link set b1 up
ip -n test link set florp up
VLAN_COUNT=1500
BASE_DEV=b1
echo Creating vlans
ip netns exec test time -p bash -c "for i in \$(seq 1 $VLAN_COUNT);
do ip -n test link add link $BASE_DEV name foo.\$i type vlan id \$i; done"
echo Bringing them up
ip netns exec test time -p bash -c "for i in \$(seq 1 $VLAN_COUNT);
do ip -n test link set foo.\$i up; done"
echo Assiging IPv6 Addresses
ip netns exec test time -p bash -c "for i in \$(seq 1 $VLAN_COUNT);
do ip -n test address add dev foo.\$i 2000::\$i/64; done"
echo Attaching to VRF
ip netns exec test time -p bash -c "for i in \$(seq 1 $VLAN_COUNT);
do ip -n test link set foo.\$i master florp; done"
On an Intel(R) Xeon(R) CPU E5-2650 v3 @ 2.30GHz machine, the performance
before the patch is (truncated):
Creating vlans
real 108.35
Bringing them up
real 4.96
Assiging IPv6 Addresses
real 19.22
Attaching to VRF
real 458.84
After the patch:
Creating vlans
real 5.59
Bringing them up
real 5.07
Assiging IPv6 Addresses
real 5.64
Attaching to VRF
real 25.37
Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Lu Wei <luwei32@huawei.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Gilad Naaman <gnaaman@drivenets.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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