On 09/08/2023 18.54, Stanislav Fomichev wrote:
This series implements initial TX metadata (offloads) for AF_XDP.
See patch #2 for the main implementation and mlx5-one for the
example on how to consume the metadata on the device side.
Starting with two types of offloads:
- request TX timestamp (and write it back into the metadata area)
- request TX checksum offload
Changes since last RFC:
- add /* private: */ comments to headers (Simon)
- handle metadata only in the first frag (Simon)
- rename xdp_hw_metadata flags (Willem)
- s/tmo_request_checksum/tmo_request_timestamp/ in xdp_metadata_ops
comment (Willem)
- Documentation/networking/xsk-tx-metadata.rst
RFC v4: https://lore.kernel.org/bpf/20230724235957.1953861-1-sdf@xxxxxxxxxx/
Performance:
I've implemented a small xskgen tool to try to saturate single tx queue:
https://github.com/fomichev/xskgen/tree/master
Here are the performance numbers with some analysis.
What is the clock freq GHz for the CPU used for this benchmark?
1. Baseline. Running with commit eb62e6aef940 ("Merge branch 'bpf:
Support bpf_get_func_ip helper in uprobes'"), nothing from this series:
- with 1400 bytes of payload: 98 gbps, 8 mpps
./xskgen -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.189130 sec, 98.357623 gbps 8.409509 mpps
- with 200 bytes of payload: 49 gbps, 23 mpps
./xskgen -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000064 packets 20960134144 bits, took 0.422235 sec, 49.640921 gbps 23.683645 mpps
2. Adding single commit that supports reserving XDP_TX_METADATA_LEN
changes nothing numbers-wise.
- baseline for 1400
./xskgen -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.189247 sec, 98.347946 gbps 8.408682 mpps
- baseline for 200
./xskgen -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 20960000000 bits, took 0.421248 sec, 49.756913 gbps 23.738985 mpps
3. Adding -M flag causes xskgen to reserve the metadata and fill it, but
doesn't set XDP_TX_METADATA descriptor option.
- new baseline for 1400 (with only filling the metadata)
./xskgen -M -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.188767 sec, 98.387657 gbps 8.412077 mpps
- new baseline for 200 (with only filling the metadata)
./xskgen -M -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 20960000000 bits, took 0.410213 sec, 51.095407 gbps 24.377579 mpps
(the numbers go sligtly up here, not really sure why, maybe some cache-related
side-effects?
Notice this change/improvement (23.7 to 24.4 Mpps) is only 1 nanosec.
- (1/24.377579-1/23.738985)*10^3 = -1.103499 nanosec
This 1 nanosec could be noise in your testlab.
4. Next, I'm running the same test but with the commit that adds actual
general infra to parse XDP_TX_METADATA (but no driver support).
Essentially applying "xsk: add TX timestamp and TX checksum offload support"
from this series. Numbers are the same.
- fill metadata for 1400
./xskgen -M -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.188430 sec, 98.415557 gbps 8.414463 mpps
- fill metadata for 200
./xskgen -M -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 20960000000 bits, took 0.411559 sec, 50.928299 gbps 24.297853 mpps
- request metadata for 1400
./xskgen -m -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.188723 sec, 98.391299 gbps 8.412389 mpps
- request metadata for 200
./xskgen -m -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000064 packets 20960134144 bits, took 0.411240 sec, 50.968131 gbps 24.316856 mpps
5. Now, for the most interesting part, I'm adding mlx5 driver support.
The mpps for 200 bytes case goes down from 23 mpps to 19 mpps, but
_only_ when I enable the metadata. This looks like a side effect
of me pushing extra metadata pointer via mlx5e_xdpi_fifo_push.
Hence, this part is wrapped into 'if (xp_tx_metadata_enabled)'
to not affect the existing non-metadata use-cases. Since this is not
regressing existing workloads, I'm not spending any time trying to
optimize it more (and leaving it up to mlx owners to purse if
they see any good way to do it).
- same baseline
./xskgen -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.189434 sec, 98.332484 gbps 8.407360 mpps
./xskgen -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000128 packets 20960268288 bits, took 0.425254 sec, 49.288821 gbps 23.515659 mpps
- fill metadata for 1400
./xskgen -M -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.189528 sec, 98.324714 gbps 8.406696 mpps
- fill metadata for 200
./xskgen -M -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000128 packets 20960268288 bits, took 0.519085 sec, 40.379260 gbps 19.264914 mpps
This change from 23 mpps to 19 mpps is approx 10 nanosec
- (1/23.738985-1/19.264914)*10^3 = -9.78 nanosec
- (1/23.515659-1/19.264914)*10^3 = -9.38 nanosec
A 10 nanosec difference is more than noise.
- request metadata for 1400
./xskgen -m -s 1400 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000000 packets 116960000000 bits, took 1.189329 sec, 98.341165 gbps 8.408102 mpps
- request metadata for 200
./xskgen -m -s 200 -b eth3 10:70:fd:48:10:77 10:70:fd:48:10:87 fe80::1270:fdff:fe48:1077 fe80::1270:fdff:fe48:1087 1 1
sent 10000128 packets 20960268288 bits, took 0.519929 sec, 40.313713 gbps 19.233642 mpps
Cc: Saeed Mahameed <saeedm@xxxxxxxxxx>
Stanislav Fomichev (9):
xsk: Support XDP_TX_METADATA_LEN
xsk: add TX timestamp and TX checksum offload support
tools: ynl: print xsk-features from the sample
net/mlx5e: Implement AF_XDP TX timestamp and checksum offload
selftests/xsk: Support XDP_TX_METADATA_LEN
selftests/bpf: Add csum helpers
selftests/bpf: Add TX side to xdp_metadata
selftests/bpf: Add TX side to xdp_hw_metadata
xsk: document XDP_TX_METADATA_LEN layout
Documentation/netlink/specs/netdev.yaml | 20 ++
Documentation/networking/index.rst | 1 +
Documentation/networking/xsk-tx-metadata.rst | 75 +++++++
drivers/net/ethernet/mellanox/mlx5/core/en.h | 4 +-
.../net/ethernet/mellanox/mlx5/core/en/xdp.c | 72 ++++++-
.../net/ethernet/mellanox/mlx5/core/en/xdp.h | 10 +-
.../ethernet/mellanox/mlx5/core/en/xsk/tx.c | 11 +-
.../net/ethernet/mellanox/mlx5/core/en_main.c | 1 +
include/linux/netdevice.h | 27 +++
include/linux/skbuff.h | 5 +-
include/net/xdp_sock.h | 61 ++++++
include/net/xdp_sock_drv.h | 13 ++
include/net/xsk_buff_pool.h | 6 +
include/uapi/linux/if_xdp.h | 36 ++++
include/uapi/linux/netdev.h | 16 ++
net/core/netdev-genl.c | 12 +-
net/xdp/xsk.c | 61 ++++++
net/xdp/xsk_buff_pool.c | 1 +
net/xdp/xsk_queue.h | 19 +-
tools/include/uapi/linux/if_xdp.h | 50 ++++-
tools/include/uapi/linux/netdev.h | 15 ++
tools/net/ynl/generated/netdev-user.c | 19 ++
tools/net/ynl/generated/netdev-user.h | 3 +
tools/net/ynl/samples/netdev.c | 6 +
tools/testing/selftests/bpf/network_helpers.h | 43 ++++
.../selftests/bpf/prog_tests/xdp_metadata.c | 31 ++-
tools/testing/selftests/bpf/xdp_hw_metadata.c | 201 +++++++++++++++++-
tools/testing/selftests/bpf/xsk.c | 17 ++
tools/testing/selftests/bpf/xsk.h | 1 +
29 files changed, 793 insertions(+), 44 deletions(-)
create mode 100644 Documentation/networking/xsk-tx-metadata.rst
Thanks for working on this :-)
--Jesper
