Star64_linux/drivers
Jussi Maki 9e2ee5c7e7 net, bonding: Add XDP support to the bonding driver
XDP is implemented in the bonding driver by transparently delegating
the XDP program loading, removal and xmit operations to the bonding
slave devices. The overall goal of this work is that XDP programs
can be attached to a bond device *without* any further changes (or
awareness) necessary to the program itself, meaning the same XDP
program can be attached to a native device but also a bonding device.

Semantics of XDP_TX when attached to a bond are equivalent in such
setting to the case when a tc/BPF program would be attached to the
bond, meaning transmitting the packet out of the bond itself using one
of the bond's configured xmit methods to select a slave device (rather
than XDP_TX on the slave itself). Handling of XDP_TX to transmit
using the configured bonding mechanism is therefore implemented by
rewriting the BPF program return value in bpf_prog_run_xdp. To avoid
performance impact this check is guarded by a static key, which is
incremented when a XDP program is loaded onto a bond device. This
approach was chosen to avoid changes to drivers implementing XDP. If
the slave device does not match the receive device, then XDP_REDIRECT
is transparently used to perform the redirection in order to have
the network driver release the packet from its RX ring. The bonding
driver hashing functions have been refactored to allow reuse with
xdp_buff's to avoid code duplication.

The motivation for this change is to enable use of bonding (and
802.3ad) in hairpinning L4 load-balancers such as [1] implemented with
XDP and also to transparently support bond devices for projects that
use XDP given most modern NICs have dual port adapters. An alternative
to this approach would be to implement 802.3ad in user-space and
implement the bonding load-balancing in the XDP program itself, but
is rather a cumbersome endeavor in terms of slave device management
(e.g. by watching netlink) and requires separate programs for native
vs bond cases for the orchestrator. A native in-kernel implementation
overcomes these issues and provides more flexibility.

Below are benchmark results done on two machines with 100Gbit
Intel E810 (ice) NIC and with 32-core 3970X on sending machine, and
16-core 3950X on receiving machine. 64 byte packets were sent with
pktgen-dpdk at full rate. Two issues [2, 3] were identified with the
ice driver, so the tests were performed with iommu=off and patch [2]
applied. Additionally the bonding round robin algorithm was modified
to use per-cpu tx counters as high CPU load (50% vs 10%) and high rate
of cache misses were caused by the shared rr_tx_counter (see patch
2/3). The statistics were collected using "sar -n dev -u 1 10". On top
of that, for ice, further work is in progress on improving the XDP_TX
numbers [4].

 -----------------------|  CPU  |--| rxpck/s |--| txpck/s |----
 without patch (1 dev):
   XDP_DROP:              3.15%      48.6Mpps
   XDP_TX:                3.12%      18.3Mpps     18.3Mpps
   XDP_DROP (RSS):        9.47%      116.5Mpps
   XDP_TX (RSS):          9.67%      25.3Mpps     24.2Mpps
 -----------------------
 with patch, bond (1 dev):
   XDP_DROP:              3.14%      46.7Mpps
   XDP_TX:                3.15%      13.9Mpps     13.9Mpps
   XDP_DROP (RSS):        10.33%     117.2Mpps
   XDP_TX (RSS):          10.64%     25.1Mpps     24.0Mpps
 -----------------------
 with patch, bond (2 devs):
   XDP_DROP:              6.27%      92.7Mpps
   XDP_TX:                6.26%      17.6Mpps     17.5Mpps
   XDP_DROP (RSS):       11.38%      117.2Mpps
   XDP_TX (RSS):         14.30%      28.7Mpps     27.4Mpps
 --------------------------------------------------------------

RSS: Receive Side Scaling, e.g. the packets were sent to a range of
destination IPs.

  [1]: https://cilium.io/blog/2021/05/20/cilium-110#standalonelb
  [2]: https://lore.kernel.org/bpf/20210601113236.42651-1-maciej.fijalkowski@intel.com/T/#t
  [3]: https://lore.kernel.org/bpf/CAHn8xckNXci+X_Eb2WMv4uVYjO2331UWB2JLtXr_58z0Av8+8A@mail.gmail.com/
  [4]: https://lore.kernel.org/bpf/20210805230046.28715-1-maciej.fijalkowski@intel.com/T/#t

Signed-off-by: Jussi Maki <joamaki@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20210731055738.16820-4-joamaki@gmail.com
2021-08-09 23:20:14 +02:00
..
accessibility
acpi
amba
android
ata
atm
auxdisplay
base
bcma
block
bluetooth
bus
cdrom
char
clk
clocksource
comedi
connector
counter
cpufreq
cpuidle
crypto
cxl
dax
dca
devfreq
dio
dma
dma-buf
edac
eisa
extcon
firewire
firmware
fpga
fsi
gnss
gpio
gpu
greybus
hid
hsi
hv
hwmon
hwspinlock
hwtracing
i2c
i3c
idle
iio
infiniband
input
interconnect
iommu
ipack
irqchip
isdn
leds
lightnvm
macintosh
mailbox
mcb
md
media
memory
memstick
message
mfd
misc
mmc
most
mtd
mux
net
nfc
ntb
nubus
nvdimm
nvme
nvmem
of
opp
parisc
parport
pci
pcmcia
perf
phy
pinctrl
platform
pnp
power
powercap
pps
ps3
ptp
pwm
rapidio
ras
regulator
remoteproc
reset
rpmsg
rtc
s390
sbus
scsi
sh
siox
slimbus
soc
soundwire
spi
spmi
ssb
staging
target
tc
tee
thermal
thunderbolt
tty
uio
usb
vdpa
vfio
vhost
video
virt
virtio
visorbus
vlynq
vme
w1
watchdog
xen
zorro
Kconfig
Makefile