The patch adds support for using need_wakeup flag in AF_XDP rings.
A new option, use-need-wakeup, is added. When this option is used,
it means that OVS has to explicitly wake up the kernel RX, using poll()
syscall and wake up TX, using sendto() syscall. This feature improves
the performance by avoiding unnecessary sendto syscalls for TX.
For RX, instead of kernel always busy-spinning on fille queue, OVS wakes
up the kernel RX processing when fill queue is replenished.
The need_wakeup feature is merged into Linux kernel bpf-next tee with commit
77cd0d7b3f25 ("xsk: add support for need_wakeup flag in AF_XDP rings") and
OVS enables it by default, if libbpf supports it. If users enable it but
runs in an older version of libbpf, then the need_wakeup feature has no effect,
and a warning message is logged.
For virtual interface, it's better set use-need-wakeup=false, since
the virtual device's AF_XDP xmit is synchronous: the sendto syscall
enters kernel and process the TX packet on tx queue directly.
On Intel Xeon E5-2620 v3 2.4GHz system, performance of physical port
to physical port improves from 6.1Mpps to 7.3Mpps.
Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: William Tu <u9012063@gmail.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
In case of failure of 'xsk_configure_all()', 'n_rxq' and 'xdpmode'
will remain in a new state. This will result in successful
reconfiguration (immediate return, because configuration is already
applied) if 'netdev_reconfigure()' will be called again.
Same issue was fixed previously for netdev-dpdk using 'dev->started'
flag in commit:
606f66507250 ("netdev-dpdk: Don't use PMD driver if not configured successfully")
Let's use similar approach with checking the 'dev->xsks' which only
exists if configuration was successful.
Additionally implemented 'netdev_afxdp_construct()' function to
explicitly initialize all the specific fields and request the
reconfiguration.
CC: William Tu <u9012063@gmail.com>
Fixes: 0de1b425962d ("netdev-afxdp: add new netdev type for AF_XDP.")
Acked-by: William Tu <u9012063@gmail.com>
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
The patch introduces experimental AF_XDP support for OVS netdev.
AF_XDP, the Address Family of the eXpress Data Path, is a new Linux socket
type built upon the eBPF and XDP technology. It is aims to have comparable
performance to DPDK but cooperate better with existing kernel's networking
stack. An AF_XDP socket receives and sends packets from an eBPF/XDP program
attached to the netdev, by-passing a couple of Linux kernel's subsystems
As a result, AF_XDP socket shows much better performance than AF_PACKET
For more details about AF_XDP, please see linux kernel's
Documentation/networking/af_xdp.rst. Note that by default, this feature is
not compiled in.
Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
