diff options
| author | Eric Dumazet <edumazet@google.com> | 2026-02-23 14:35:01 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-02-25 04:44:33 +0300 |
| commit | fca59a2dd0b8ce55ad090707ec425d6d37b8b932 (patch) | |
| tree | f575b98517ef2ecab8e330b4433153b1b772cb23 /net | |
| parent | a09eb622f383e6ceff7d55072cba4d4b8234d5d5 (diff) | |
| download | linux-fca59a2dd0b8ce55ad090707ec425d6d37b8b932.tar.xz | |
tcp: reduce calls to tcp_schedule_loss_probe()
For RPC workloads, we alternate tcp_schedule_loss_probe() calls from
output path and from input path, with tp->packets_out value
oscillating between !zero and zero, leading to poor branch prediction.
Move tp->packets_out check from tcp_schedule_loss_probe() to
tcp_set_xmit_timer().
We avoid one call to tcp_schedule_loss_probe() from tcp_ack()
path for typical RPC workloads, while improving branch prediction.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260223113501.4070245-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e7b41abb82aa..6c3f1d031444 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3552,7 +3552,7 @@ void tcp_rearm_rto(struct sock *sk) /* Try to schedule a loss probe; if that doesn't work, then schedule an RTO. */ static void tcp_set_xmit_timer(struct sock *sk) { - if (!tcp_schedule_loss_probe(sk, true)) + if (!tcp_sk(sk)->packets_out || !tcp_schedule_loss_probe(sk, true)) tcp_rearm_rto(sk); } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 1ef419c66a0e..46bd48cf776a 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3135,7 +3135,7 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) * not in loss recovery, that are either limited by cwnd or application. */ if ((early_retrans != 3 && early_retrans != 4) || - !tp->packets_out || !tcp_is_sack(tp) || + !tcp_is_sack(tp) || (icsk->icsk_ca_state != TCP_CA_Open && icsk->icsk_ca_state != TCP_CA_CWR)) return false; |