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| author | Paolo Abeni <pabeni@redhat.com> | 2017-06-21 11:45:31 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-06-21 11:43:01 -0400 |
| commit | 34cfb542b5b1762c73479a4a61e0a3b77253f876 (patch) | |
| tree | 0e7db516c60cf9e2b9c306be6b18fc0f50099a2c /include | |
| parent | 28b5ba2aa0f55d80adb2624564ed2b170c19519e (diff) | |
| download | linux-34cfb542b5b1762c73479a4a61e0a3b77253f876.tar.bz2 | |
sock: avoid dirtying incoming_cpu if not needed
for connected socket, the incoming_cpu field in the sock struct
is not going to change frequently, but we are setting it
unconditionally for each packet.
Since sk_incoming_cpu and sk_flags share the same cacheline,
and the latter is access by udp_recvmsg(), this cause a cache
miss for each packet for UDP connected socket.
With this patch, we set the incoming cpu field only when the
ingress cpu really changes.
This gives a small but measurable performance improvement for
connected UDP socket.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/sock.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 858891c36f94..00d09140e354 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -907,7 +907,10 @@ static inline int sk_backlog_rcv(struct sock *sk, struct sk_buff *skb) static inline void sk_incoming_cpu_update(struct sock *sk) { - sk->sk_incoming_cpu = raw_smp_processor_id(); + int cpu = raw_smp_processor_id(); + + if (unlikely(sk->sk_incoming_cpu != cpu)) + sk->sk_incoming_cpu = cpu; } static inline void sock_rps_record_flow_hash(__u32 hash) |