populate_lru() zero-initializes atime:
struct real_pos_lru lru = { .pos = real_idx };
connection_table_lookup() treats UDP entries with
cur_time - atime > 30s as expired, so every pre-populated entry
expires immediately. Calibration masks this on the CPU it runs on,
but if validation migrates to another CPU:
[udp-v4-lru-hit] COUNTER FAIL: LRU misses=1, expected 0
Initialize atime from CLOCK_MONOTONIC for UDP flows.
Fixes: a4b5ba8187 ("selftests/bpf: Add XDP load-balancer benchmark driver")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260520133338.3392667-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Wire up the userspace side of the XDP load-balancer benchmark.
24 scenarios cover the full code-path matrix: TCP/UDP, IPv4/IPv6,
cross-AF encap, LRU hit/miss/diverse/cold, consistent-hash bypass,
SYN/RST flag handling, and early exits (unknown VIP, non-IP, ICMP,
fragments, IP options).
Before benchmarking each scenario validates correctness: the output
packet is compared byte-for-byte against a pre-built expected packet
and BPF map counters are checked against the expected values.
Usage:
sudo ./bench -a -w3 -p1 xdp-lb --scenario tcp-v4-lru-hit
sudo ./bench xdp-lb --list-scenarios
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260427232313.1582588-7-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
