netdev - [PATCH net-next 1/9] tcp: switch tcp_clock_ns() to CLOCK

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Date:   Fri, 21 Sep 2018 08:51:46 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>, Van Jacobson <vanj@...gle.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next 1/9] tcp: switch tcp_clock_ns() to CLOCK_TAI base

TCP pacing is either implemented in sch_fq or internally.
We have the goal of being able to offload pacing on the NICS.

TCP will soon provide per skb skb->tstamp as early departure time.

Like ETF in commit 25db26a91364 ("net/sched: Introduce the ETF Qdisc")
we chose CLOCK_T as the clock base, so that TCP and pacers can share
a common clock, to get better RTT samples (without pacing artificially
inflating these samples).

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/tcp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 770917d0caa71896b6adac06a62b150bfdc72836..c6f0bc1dc6782a1976c06932e846b3f6d708ba9f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -732,7 +732,7 @@ void tcp_send_window_probe(struct sock *sk);
 
 static inline u64 tcp_clock_ns(void)
 {
-	return local_clock();
+	return ktime_get_tai_ns();
 }
 
 static inline u64 tcp_clock_us(void)
-- 
2.19.0.444.g18242da7ef-goog