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authorEric Dumazet <edumazet@google.com>2018-10-15 09:37:52 -0700
committerDavid S. Miller <davem@davemloft.net>2018-10-15 22:56:41 -0700
commit5f6188a8003d080e3753b8f14f4a5a2325ae1ff6 (patch)
tree17f35c12eeef92a69902b197a73c1123eaac9e63
parentnet: bridge: fix a possible memory leak in __vlan_add (diff)
downloadlinux-dev-5f6188a8003d080e3753b8f14f4a5a2325ae1ff6.tar.xz
linux-dev-5f6188a8003d080e3753b8f14f4a5a2325ae1ff6.zip
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>
-rw-r--r--include/linux/tcp.h1
-rw-r--r--net/ipv4/tcp_output.c9
-rw-r--r--net/ipv4/tcp_timer.c2
3 files changed, 8 insertions, 4 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 848f5b25e178..8ed77bb4ed86 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -249,6 +249,7 @@ struct tcp_sock {
u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
u64 tcp_wstamp_ns; /* departure time for next sent data packet */
+ u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */
/* RTT measurement */
u64 tcp_mstamp; /* most recent packet received/sent */
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);
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 61023d50cd60..676020663ce8 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;