diff options
| author | Eric Dumazet <edumazet@google.com> | 2026-01-16 19:44:02 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-01-21 05:25:33 +0300 |
| commit | 79bfa5fb85870d44a5368790dbf5ccce007e6e9f (patch) | |
| tree | d8e9579982dc8548bde3a94f34ec93c75a38da54 | |
| parent | ee7be82f8c7e753e38dcf3add7ba65b543d49bd6 (diff) | |
| download | linux-79bfa5fb85870d44a5368790dbf5ccce007e6e9f.tar.xz | |
net: fclone allocation small optimization
After skb allocation, initial skb->fclone value is 0 (SKB_FCLONE_UNAVAILABLE)
We can replace one RMW sequence with a single OR instruction.
movzbl 0x7e(%r13),%eax // skb->fclone = SKB_FCLONE_ORIG;
and $0xf3,%al
or $0x4,%al
mov %al,0x7e(%r13)
->
or $0x4,0x7e(%r13) // skb->fclone |= SKB_FCLONE_ORIG;
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260116164402.1872649-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/core/skbuff.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index f2367818c130..1c2b9ae7bce6 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -723,7 +723,14 @@ fallback: fclones = container_of(skb, struct sk_buff_fclones, skb1); - skb->fclone = SKB_FCLONE_ORIG; + /* skb->fclone is a 2bits field. + * Replace expensive RMW (skb->fclone = SKB_FCLONE_ORIG) + * with a single OR. + */ + BUILD_BUG_ON(SKB_FCLONE_UNAVAILABLE != 0); + DEBUG_NET_WARN_ON_ONCE(skb->fclone != SKB_FCLONE_UNAVAILABLE); + skb->fclone |= SKB_FCLONE_ORIG; + refcount_set(&fclones->fclone_ref, 1); } |