diff options
| author | Eric Dumazet <edumazet@google.com> | 2018-10-15 19:37:52 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-10-16 08:56:41 +0300 |
| commit | 5f6188a8003d080e3753b8f14f4a5a2325ae1ff6 (patch) | |
| tree | 17f35c12eeef92a69902b197a73c1123eaac9e63 /net/ipv4/tcp_output.c | |
| parent | 1a3aea2534f4f3083f29b2b047aa83a9d6c777a4 (diff) | |
| download | linux-5f6188a8003d080e3753b8f14f4a5a2325ae1ff6.tar.xz | |
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>
Diffstat (limited to 'net/ipv4/tcp_output.c')
| -rw-r--r-- | net/ipv4/tcp_output.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 059b67af28b1..f14df66a0c85 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -52,9 +52,8 @@ void tcp_mstamp_refresh(struct tcp_sock *tp) { u64 val = tcp_clock_ns(); - /* departure time for next data packet */ - if (val > tp->tcp_wstamp_ns) - tp->tcp_wstamp_ns = val; + if (val > tp->tcp_clock_cache) + tp->tcp_clock_cache = val; val = div_u64(val, NSEC_PER_USEC); if (val > tp->tcp_mstamp) @@ -1050,6 +1049,10 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, if (unlikely(!skb)) return -ENOBUFS; } + + /* TODO: might take care of jitter here */ + tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); + skb->skb_mstamp_ns = tp->tcp_wstamp_ns; inet = inet_sk(sk); |