sock_recv_ts_and_drops() unconditionally set sk->sk_stamp for
every packet, even if the SOCK_TIMESTAMP flag is not set in the
related socket.
If selinux is enabled, this cause a cache miss for every packet
since sk->sk_stamp and sk->sk_security share the same cacheline.
With this change sk_stamp is set only if the SOCK_TIMESTAMP
flag is set, and is cleared for the first packet, so that the user
perceived behavior is unchanged.
This gives up to 5% speed-up under udp-flood with small packets.
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
include/net/sock.h | 5 ++++-
net/core/sock.c | 2 +-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index cb241a0..8e53158 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2239,6 +2239,7 @@ sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb)
void __sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb);
+#define SK_DEFAULT_STAMP (-1L * NSEC_PER_SEC)
static inline void sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb)
{
@@ -2249,8 +2250,10 @@ static inline void sock_recv_ts_and_drops(struct msghdr
*msg, struct sock *sk,
if (sk->sk_flags & FLAGS_TS_OR_DROPS || sk->sk_tsflags & TSFLAGS_ANY)
__sock_recv_ts_and_drops(msg, sk, skb);
- else
+ else if (unlikely(sk->sk_flags & SOCK_TIMESTAMP))
sk->sk_stamp = skb->tstamp;
+ else if (unlikely(sk->sk_stamp == SK_DEFAULT_STAMP))
+ sk->sk_stamp = 0;
}
void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags);
diff --git a/net/core/sock.c b/net/core/sock.c
index 1a58a9d..392f9b6 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2613,7 +2613,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT;
sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
- sk->sk_stamp = ktime_set(-1L, 0);
+ sk->sk_stamp = SK_DEFAULT_STAMP;
#ifdef CONFIG_NET_RX_BUSY_POLL
sk->sk_napi_id = 0;
--
2.9.3
