tcp: do not change tcp_wstamp_ns in tcp_mstamp_refresh
In EDT design, I made the mistake of using tcp_wstamp_ns
to store the last tcp_clock_ns() sample and to store the
pacing virtual timer.
This causes major regressions at high speed flows.
Introduce tcp_clock_cache to store last tcp_clock_ns().
This is needed because some arches have slow high-resolution
kernel time service.
tcp_wstamp_ns is only updated when a packet is sent.
Note that we can remove tcp_mstamp in the future since
tcp_mstamp is essentially tcp_clock_cache/1000, so the
apparent socket size increase is temporary.
Fixes: 9799ccb0e984 ("tcp: add tcp_wstamp_ns socket field")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 61023d5..6760206 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -360,7 +360,7 @@ static void tcp_probe_timer(struct sock *sk)
*/
start_ts = tcp_skb_timestamp(skb);
if (!start_ts)
- skb->skb_mstamp_ns = tp->tcp_wstamp_ns;
+ skb->skb_mstamp_ns = tp->tcp_clock_cache;
else if (icsk->icsk_user_timeout &&
(s32)(tcp_time_stamp(tp) - start_ts) > icsk->icsk_user_timeout)
goto abort;