From: Willem de Bruijn <will...@google.com>
Segmentation offload reduces cycles/byte for large packets by
amortizing the cost of protocol stack traversal.
This patchset implements GSO for UDP. A process can concatenate and
submit multiple datagrams to the same destination in one send call
by setting socket option SOL_UDP/UDP_SEGMENT with the segment size,
or passing an analogous cmsg at send time.
The stack will send the entire large (up to network layer max size)
datagram through the protocol layer. At the GSO layer, it is broken
up in individual segments. All receive the same network layer header
and UDP src and dst port. All but the last segment have the same UDP
header, but the last may differ in length and checksum.
Initial results show a significant reduction in UDP cycles/byte.
See the main patch for more details and benchmark results.
udp
876 MB/s 14873 msg/s 624666 calls/s
11,205,777,429 cycles
udp gso
2139 MB/s 36282 msg/s 36282 calls/s
11,204,374,561 cycles
The patch set is broken down as follows:
- patch 1 is a prerequisite: code rearrangement, noop otherwise
- patch 2 is the core feature
- patch 3,4,6 are refinements
- patch 5 adds the cmsg interface
- patch 7..10 are tests
This idea was presented previously at netconf 2017-2
http://vger.kernel.org/netconf2017_files/rx_hardening_and_udp_gso.pdf
Changes RFC -> v1
- MSG_MORE:
fixed, by allowing checksum offload with corking if gso
- SKB_GSO_UDP_L4:
made independent from SKB_GSO_UDP
and removed skb_is_ufo() wrapper
- NETIF_F_GSO_UDP_L4:
add to netdev_features_string
and to netdev-features.txt
add BUILD_BUG_ON to match SKB_GSO_UDP_L4 value
- UDP_MAX_SEGMENTS:
introduce limit on number of segments per gso skb
to avoid extreme cases like IP_MAX_MTU/IPV4_MIN_MTU
- CHECKSUM_PARTIAL:
test against missing feature after ndo_features_check
if not supported return error, analogous to udp_send_check
- MSG_ZEROCOPY: removed, deferred for now
Willem de Bruijn (11):
udp: expose inet cork to udp
udp: add gso
udp: better wmem accounting on gso
udp: paged allocation with gso
udp: add gso segment cmsg
udp: add gso support to virtual devices
selftests: udp gso
selftests: udp gso with connected sockets
selftests: udp gso with corking
selftests: udp gso benchmark
Documentation/networking/netdev-features.txt | 7 +
include/linux/netdev_features.h | 5 +-
include/linux/netdevice.h | 1 +
include/linux/skbuff.h | 2 +
include/linux/udp.h | 3 +
include/net/inet_sock.h | 1 +
include/net/ip.h | 3 +-
include/net/ipv6.h | 2 +
include/net/udp.h | 5 +
include/uapi/linux/udp.h | 1 +
net/core/ethtool.c | 1 +
net/core/skbuff.c | 2 +
net/ipv4/ip_output.c | 41 +-
net/ipv4/udp.c | 80 ++-
net/ipv4/udp_offload.c | 68 +-
net/ipv6/ip6_offload.c | 6 +-
net/ipv6/ip6_output.c | 45 +-
net/ipv6/udp.c | 31 +-
net/ipv6/udp_offload.c | 19 +-
tools/testing/selftests/net/.gitignore | 3 +
tools/testing/selftests/net/Makefile | 4 +-
tools/testing/selftests/net/udpgso.c | 621 ++++++++++++++++++
tools/testing/selftests/net/udpgso.sh | 29 +
tools/testing/selftests/net/udpgso_bench.sh | 74 +++
tools/testing/selftests/net/udpgso_bench_rx.c | 265 ++++++++
tools/testing/selftests/net/udpgso_bench_tx.c | 420 ++++++++++++
26 files changed, 1688 insertions(+), 51 deletions(-)
create mode 100644 tools/testing/selftests/net/udpgso.c
create mode 100755 tools/testing/selftests/net/udpgso.sh
create mode 100755 tools/testing/selftests/net/udpgso_bench.sh
create mode 100644 tools/testing/selftests/net/udpgso_bench_rx.c
create mode 100644 tools/testing/selftests/net/udpgso_bench_tx.c
--
2.17.0.441.gb46fe60e1d-goog
