Ovs dpdk hwoffload way to full offload

1© 2018 Mellanox Technologies
Towards VXLAN full hardware offload
March 2019, roni bar yanai
OVS-DPDK HW-
OFFLOAD

Agenda
Motivation
Hardware offload in OVS
VXLAN full hardware offload

Motivation

Demand Increases
Cloud
NFV
HPC
Storage
SDN, Tunneling, Isolation, Connection Tracking requires complex switching/routing.
Switching becomes the current bottleneck of network virtualization, even
with DPDK.
Requirement:
 Higher PPS
 Lower Latency
 Less Host CPU usage for moving packets
 Jitter
We are looking for the next performance scale up x3-x10

OLD HW Accelerations
 Dumb NIC
 CHKSUM/TSO/LRO/RSS
 Tunneling
NEW HW Accelerations
 Smart(SoC)/Intelligent NIC
 Rule Based
 Varity of Matches and Actions
 Switching Capabilities (e-switch)
Network Hardware Acceleration is already here

OVS a great opportunity for hardware
acceleration Integration
 Support for different OS/Containers
 Support of orchestration
 Bring the best performance to the guest as an infra.
 Guest can get performance much closer to
native SR-IOV.
 Buy A better nic and you get even better
performance to the guest.
Challenges:
 Full hardware acceleration bypassing OVS.
(SR-IOV, vDPA will have same issues).
 Different hardware with different
architecture and API
SR-IOV NIC
OVS
VM
VM
eSwitch
VM
SR-IOV

Representors
 Representor ports are a ethdev
modeling of eSwitch ports
 The VF representor supports the
following operations
• Send packet from the host CPU to VF
(OVS Re-injection)
• Receive of eSwitch “miss” packets
• Flow configuration (add/remove)
• Flow statistics read for the purposes of
aging and statistics
hypervisor
OVS
vPort1
representor
Ext port
PF
vPort
1
VM
vPort2
representor
vPort3
representor
HW eSwitch
vPort
2
VM
vPort
3
VM
VF
1
VF
2
VF
3
PF
Net device
eSW port
Flows
FDB

 DPDK RTE_FLOW was defined as the hardware API
 Many of netdev_flow common functionality already exists:
• Network matching with masks: Ethernet, IP, TCP, VXLAN…etc.
• Tables
• Priorities
• Actions: Decap, Modify, Encap, Mark…etc
 MARK and RSS hardware offload already integrated into OVS-DPDK.
 Mark and RSS saves the first classification
RTE_FLOW Common API for Hardware offload

Hardware offload in
OVS

Hardware offload next steps
 Searching for DP flow by matching packet
fields
 DP Flow actions are executed
 Execution may include changing the packet
(VXLAN pop) and recircle the packet again.
Packet will have to run through the same
process again
 Some actions such as connection tracking
might include another search, access and
modification
 All is done in software and some actions
require additional memory access
 VXLAN with connection tracking will have
at least three cycles of processing. rx, pop ,
and connection tracking
Match Action
recircle
output
upcall
• Waste of CPU cycles
• Latency
• Throughput

Software based vs Hardware based
OVS-vswitchd
OVS DPDK DP
OVS-vswitchd
OVS DPDK DP
Smart Nic Hardware
Traditional Model: All Software
High Latency, Low Bandwidth, CPU Intensive
ConnectX: Hardware Offload
Low Latency, High Bandwidth, Efficient CPU
First flow packet Fallback FRWD path HW forwarded Packets

OVS DPDK with/without full HW offload
7.6
MPPS
66
MPPS
0
10
20
30
40
50
60
70
OVS over DPDK OVS Offload
MillionPacketPerSecond
OVS over DPDK OVS Offload
Test Full HW
offload
Without
offload
Benefit
1 Flow
VXLAN
66M PPS 7.6M PPS
(VLAN)
8.6X
60K flows
VXLAN
19.8M PPS 1.9M PPS 10.4X
4 cores1 core. 100%
idle

OVS DPDK with/without partial HW offload
Test Partial HW
offload
Without
offload
Benefit
1 Flow
VXLAN
10M PPS 3M PPS 3.3X
32K flows
VXLAN
7.5M PPS 2.2M PPS 3.4X
0
1
2
3
4
5
6
7
8
9
10
no offload offload
MPPS
no offload offload
Partial: VXLAN pop is done in
hardware, and than mark and RSS.
The forwarding is done in SW and
limited by the PMD thread
2 cores

VXLAN full offload

VXLAN full offload
Why start with VXLAN offload?
 Common use case
 Same implementation with minor changes can be implemented for other tunneling.
 Simple compared to CT and can be supported with current RTE_FLOW
implementation. CT requires non raw networking fields such a ZONE,MARK…etc.
 RX benefit can be effective where processing continues on SW (CT is common
use case), because VXLAN pop is done first.
 Market is starving for more PPS and VXLAN hardware offload has enough benefit
for being deployed full/partial.

OVS-DPDK Hardware offload guidelines
Generic: Any hardware that implements the required RTE_FLOW
match/action should support it.
Minimal Interface with OVS code.
Follow OVS netdev-flow as close as possible.
Incremental.

Vxlan in OVS DPDK
There are 2 level of switch that are
cascade
The HW classification accelerate
only the lower switch (br-phys1)
br-phy1 is a kernel interface for
vxlan
The OVS data path executes
pop_tnl and inner packet
classification (and output).
TX Direction, only classification of
inner packet
Br-phy1
Br-int
vPorts
VF
2
VF
3
VF
n
T
a
p
VMVM VM
Uplink/
PF
VF
1
T
a
p
VM
vxlan
VM VM
IP
address
Br-phy1

TNL_PUSH
 recirc_id(0),in_port(2),packet_type(ns=0,id=0),eth(src=52:54:00:a6:9b:1f,dst=6e:7f:14:8b:f9:99),eth_typ
e(0x0800),ipv4(tos=0/0x3,frag=no), packets:4, bytes:594, used:2.855s, flags:SFP.,
actions:clone(tnl_push(tnl_port(4),header(size=50,type=4,eth(dst=98:03:9b:64:0b:fa,src=98:03:9b:64:0b:
32,dl_type=0x0800),ipv4(src=11.0.0.36,dst=11.0.0.35,proto=17,tos=0,ttl=64,frag=0x4000),udp(src=0,dst=
4789,csum=0x0),vxlan(flags=0x8000000,vni=0x64)),out_port(6)),5)
TNL_PUSH is straight forward.
• flow contains the entire header as byte array
• Can be implemented with RTE_FLOW raw encap
• Only UDP port and checksum are fixed in code (can be offloaded
to hardware in any case)
Inner PacketVXLAN
(eth,ip,udp,vxlan)

TNL_POP
 recirc_id(0),in_port(5),packet_type(ns=0,id=0),eth(src=98:03:9b:64:0b:fa,dst=98:03:9b:64:0b:32),eth_ty
pe(0x0800),ipv4(dst=11.0.0.36,proto=17,frag=no),udp(dst=4789), packets:5, bytes:723, used:1.142s,
actions:tnl_pop(4)
 tunnel(tun_id=0x64,src=11.0.0.35,dst=11.0.0.36,flags(-df-
csum+key)),recirc_id(0),in_port(4),packet_type(ns=0,id=0),eth(src=6e:7f:14:8b:f9:99,dst=52:54:00:a6:9
b:1f),eth_type(0x0800),ipv4(frag=no), packets:5, bytes:473, used:2.854s, flags:FP., actions:2
Executed by two netdev_flow flows
• tnl_pop, remove tnl and forward to vport (not a DPDK
entity).
• second flow has match on meta data

odp_port_t in_port = flow->flow.in_port.odp_port;
.
.
port = dp_netdev_lookup_port(pmd->dp, in_port);
.
.
ret = netdev_flow_put(port->netdev, &offload->match,
CONST_CAST(struct nlattr *, offload->actions),
offload->actions_len, &flow->mega_ufid, &info,
NULL);
vport_netdev
VPORT has no RTE offload and
requires some special handling

VPORT can be represented as a Table
The action of a rule can be to go to other table.
It can be use to chain classification
Table 0
Match A  flow ID 1
Match B  drop
Match C  Table 1
Match D  Table 1
Default no flow ID
Table 1
Match E  flow ID 2
Match F  flow ID 3
Default flow ID 4

VXLAN HW offload concept
If the action is to forward to vport add HW rule to
point to a table representing the vport interface.
If the in port of the rule is vport (like vxlan)
add rule to the table representing the interface. We
don’t pop the tunnel yet! We can’t have metadata.
vport will match on both inner and outer (already in
the flow), meta data will matched against the outer
header. Match will work exactly the same ,because
we didn’t strip the tunnel yet.
The vport will execute the pop.
The vport will mark/rss or output
the packet.
Br-phy1
Br-int
VM
Uplink/
PF
Tap
VM
vxlan
IP
address
Br-phy1MatchA  flow ID 1
MatchB  drop + count
MatchC  Table 1 + count
MatchD  Table 1 + count
Default no flow ID
MatchE  flow ID 2
MatchF  flow ID 3
Default flow ID 4
Table 1
all the rules that the src port
is the vxlan interface
VM
Tap
VM
Table 0

Vxlan HW offload
vport table has a default rule that will
forward to software if no other match.
flows are not atomic, it is possible that
the vport table will not have a match yet,
but packets will be forwarded to it.
vport is represented by HW table but it is
not an OVS table, we still forward only
on table 0.
Exception: if we have a match on the
default flow, we already did some of the
way, we mark with a special mark.
Special mark will be mapped to VXLAN
software implantation in this case.
Br-phy1
Br-int
VM
Uplink/
PF
Tap
VM
vxlan
IP
address
Default no flow ID
Default flow ID 4
Table 1
VM
Tap
VM
Table 0

Vxlan HW offload
We offload only if all actions are
supported.
In case offload is not yet possible, we
fallback to mark/rss.
If flow offload include jump, we must
add a counter because it won’t hit
software.
Software counters must read the
hardware counters for such flows or
else flow will age out.
Br-phy1
Br-int
VM
Uplink/
PF
Tap
VM
vxlan
IP
address
Default no flow ID
Default flow ID 4
Table 1
VM
Tap
VM
Table 0

VPORT offloads
Since netdev_flow api uses the odp_port and netdev to offload, we need to add offload
API for vport which are part of DPDK DP.
The actual hardware that the rule will be configured is any uplink.
If we have also output action we must verify we configure output rule only on the uplink
which is on the same e-switch as the output port (VF).
 Theoretically, packet can get from any uplink and go to any VF (or even PF).
 for hardware offload it is possible to send packets that are on the same e-switch (each port belongs to
e-switch domain which is a unique entity).
 From performance point of view, we expect users to have packets forwarded only on same switch (for
partial we do both because it goes to software anyway).

Where we are?
We implemented partial offload and did a performance testing
Started to push up stream (first phase is code split which is currently
in review process).
We are preparing the rest of the patches.
We started coding the full offload, our expectation is to complete it
on the next two months.
We started CT offload architecture.

Thank You

Ovs dpdk hwoffload way to full offload

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