bpf: Optimize word-sized keys for resizable hashtable

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Specialize the lookup/update/delete paths for keys whose size matches
sizeof(long) (4 bytes on 32-bit, 8 bytes on 64-bit). A static-const
rhashtable_params lets the compiler inline a custom XOR-fold hashfn and
a single-word equality cmpfn, eliminating the indirect jhash dispatch.
The same hashfn and cmpfn are installed into rhashtable's stored params
at rhashtable_init time, so the rehash worker, slow-path inserts, and
rhashtable_next_key() all agree with the inlined fast paths.

The seq_file BPF iterator uses rhashtable_walk_* and is unaffected.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260605-rhash-v7-7-5b8e05f8630d@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Mykyta Yatsenko 2026-06-05 04:41:24 -07:00 • committed by Alexei Starovoitov

parent 6905f86012

commit 9dcbb5045f

1 changed files with 45 additions and 2 deletions

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kernel/bpf/hashtab.c

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