* [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack()
@ 2020-09-30 12:54 Eric Dumazet
2020-09-30 12:54 ` [PATCH net-next 1/2] inet: remove icsk_ack.blocked Eric Dumazet
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Eric Dumazet @ 2020-09-30 12:54 UTC (permalink / raw)
To: David S . Miller
Cc: netdev, Soheil Hassas Yeganeh, Neal Cardwell, Yuchung Cheng,
Eric Dumazet, Eric Dumazet
From: Eric Dumazet <edumazet@google.com>
We had outages caused by repeated skb allocation failures in tcp_send_ack()
It is time to add exponential backoff to reduce number of attempts.
Before doing so, first patch removes icsk_ack.blocked to make
room for a new field (icsk_ack.retry)
Eric Dumazet (2):
inet: remove icsk_ack.blocked
tcp: add exponential backoff in __tcp_send_ack()
include/net/inet_connection_sock.h | 5 +++--
net/dccp/timer.c | 1 -
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/tcp.c | 6 ++----
net/ipv4/tcp_output.c | 18 ++++++++++--------
net/ipv4/tcp_timer.c | 1 -
6 files changed, 16 insertions(+), 17 deletions(-)
--
2.28.0.806.g8561365e88-goog
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net-next 1/2] inet: remove icsk_ack.blocked
2020-09-30 12:54 [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() Eric Dumazet
@ 2020-09-30 12:54 ` Eric Dumazet
2020-09-30 13:45 ` Soheil Hassas Yeganeh
2020-09-30 12:54 ` [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack() Eric Dumazet
2020-09-30 21:21 ` [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() David Miller
2 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2020-09-30 12:54 UTC (permalink / raw)
To: David S . Miller
Cc: netdev, Soheil Hassas Yeganeh, Neal Cardwell, Yuchung Cheng,
Eric Dumazet, Eric Dumazet
From: Eric Dumazet <edumazet@google.com>
TCP has been using it to work around the possibility of tcp_delack_timer()
finding the socket owned by user.
After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events")
we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery,
so we can get rid of icsk_ack.blocked
This frees space that following patch will reuse.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
include/net/inet_connection_sock.h | 4 ++--
net/dccp/timer.c | 1 -
net/ipv4/inet_connection_sock.c | 2 +-
net/ipv4/tcp.c | 6 ++----
net/ipv4/tcp_output.c | 7 ++-----
net/ipv4/tcp_timer.c | 1 -
6 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index dc763ca9413cc9c6279a59f9d1776cf2dbb1e853..79875f976190750819948425e63dd0309c699050 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -110,7 +110,7 @@ struct inet_connection_sock {
__u8 pending; /* ACK is pending */
__u8 quick; /* Scheduled number of quick acks */
__u8 pingpong; /* The session is interactive */
- __u8 blocked; /* Delayed ACK was blocked by socket lock */
+ /* one byte hole. */
__u32 ato; /* Predicted tick of soft clock */
unsigned long timeout; /* Currently scheduled timeout */
__u32 lrcvtime; /* timestamp of last received data packet */
@@ -198,7 +198,7 @@ static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
#endif
} else if (what == ICSK_TIME_DACK) {
- icsk->icsk_ack.blocked = icsk->icsk_ack.pending = 0;
+ icsk->icsk_ack.pending = 0;
#ifdef INET_CSK_CLEAR_TIMERS
sk_stop_timer(sk, &icsk->icsk_delack_timer);
#endif
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 927c796d76825439a35c4deb3fb2e45e4313f9b3..a934d293237366aeca87bd3c32241880639291c5 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -176,7 +176,6 @@ static void dccp_delack_timer(struct timer_list *t)
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
- icsk->icsk_ack.blocked = 1;
__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
sk_reset_timer(sk, &icsk->icsk_delack_timer,
jiffies + TCP_DELACK_MIN);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index b457dd2d6c75b2f63bc7849474ac909adb14d603..4148f5f78f313cde1e0596b9eb3696df16e3f990 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -564,7 +564,7 @@ void inet_csk_clear_xmit_timers(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
- icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
+ icsk->icsk_pending = icsk->icsk_ack.pending = 0;
sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
sk_stop_timer(sk, &icsk->icsk_delack_timer);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2a8bfa89a5159837e3687e4e0f8cddba7fe54899..ed2805564424a90f003eed867bbed7f5ac4ae833 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1538,10 +1538,8 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
if (inet_csk_ack_scheduled(sk)) {
const struct inet_connection_sock *icsk = inet_csk(sk);
- /* Delayed ACKs frequently hit locked sockets during bulk
- * receive. */
- if (icsk->icsk_ack.blocked ||
- /* Once-per-two-segments ACK was not sent by tcp_input.c */
+
+ if (/* Once-per-two-segments ACK was not sent by tcp_input.c */
tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
/*
* If this read emptied read buffer, we send ACK, if
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 386978dcd318d84af486d0d1a5bb1786f4a493cf..6bd4e383030ea20441332a30e98fbda8cd90f84a 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3911,11 +3911,8 @@ void tcp_send_delayed_ack(struct sock *sk)
/* Use new timeout only if there wasn't a older one earlier. */
if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
- /* If delack timer was blocked or is about to expire,
- * send ACK now.
- */
- if (icsk->icsk_ack.blocked ||
- time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
+ /* If delack timer is about to expire, send ACK now. */
+ if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
tcp_send_ack(sk);
return;
}
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 0c08c420fbc21a98dedf72148ea2a6f85bf3ff7a..6c62b9ea1320d9bbd26ed86b9f41de02fee6c491 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -331,7 +331,6 @@ static void tcp_delack_timer(struct timer_list *t)
if (!sock_owned_by_user(sk)) {
tcp_delack_timer_handler(sk);
} else {
- icsk->icsk_ack.blocked = 1;
__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
/* deleguate our work to tcp_release_cb() */
if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))
--
2.28.0.806.g8561365e88-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack()
2020-09-30 12:54 [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() Eric Dumazet
2020-09-30 12:54 ` [PATCH net-next 1/2] inet: remove icsk_ack.blocked Eric Dumazet
@ 2020-09-30 12:54 ` Eric Dumazet
2020-09-30 15:00 ` Soheil Hassas Yeganeh
2020-09-30 21:21 ` [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() David Miller
2 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2020-09-30 12:54 UTC (permalink / raw)
To: David S . Miller
Cc: netdev, Soheil Hassas Yeganeh, Neal Cardwell, Yuchung Cheng,
Eric Dumazet, Eric Dumazet
From: Eric Dumazet <edumazet@google.com>
Whenever host is under very high memory pressure,
__tcp_send_ack() skb allocation fails, and we setup
a 200 ms (TCP_DELACK_MAX) timer before retrying.
On hosts with high number of TCP sockets, we can spend
considerable amount of cpu cycles in these attempts,
add high pressure on various spinlocks in mm-layer,
ultimately blocking threads attempting to free space
from making any progress.
This patch adds standard exponential backoff to avoid
adding fuel to the fire.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
include/net/inet_connection_sock.h | 3 ++-
net/ipv4/tcp_output.c | 11 ++++++++---
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 79875f976190750819948425e63dd0309c699050..7338b3865a2a3d278dc27c0167bba1b966bbda9f 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -110,7 +110,7 @@ struct inet_connection_sock {
__u8 pending; /* ACK is pending */
__u8 quick; /* Scheduled number of quick acks */
__u8 pingpong; /* The session is interactive */
- /* one byte hole. */
+ __u8 retry; /* Number of attempts */
__u32 ato; /* Predicted tick of soft clock */
unsigned long timeout; /* Currently scheduled timeout */
__u32 lrcvtime; /* timestamp of last received data packet */
@@ -199,6 +199,7 @@ static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
#endif
} else if (what == ICSK_TIME_DACK) {
icsk->icsk_ack.pending = 0;
+ icsk->icsk_ack.retry = 0;
#ifdef INET_CSK_CLEAR_TIMERS
sk_stop_timer(sk, &icsk->icsk_delack_timer);
#endif
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 6bd4e383030ea20441332a30e98fbda8cd90f84a..bf48cd73e96787a14b6f9af8beddb1067a7cb8dc 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3941,10 +3941,15 @@ void __tcp_send_ack(struct sock *sk, u32 rcv_nxt)
buff = alloc_skb(MAX_TCP_HEADER,
sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN));
if (unlikely(!buff)) {
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ unsigned long delay;
+
+ delay = TCP_DELACK_MAX << icsk->icsk_ack.retry;
+ if (delay < TCP_RTO_MAX)
+ icsk->icsk_ack.retry++;
inet_csk_schedule_ack(sk);
- inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
- inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
- TCP_DELACK_MAX, TCP_RTO_MAX);
+ icsk->icsk_ack.ato = TCP_ATO_MIN;
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX);
return;
}
--
2.28.0.806.g8561365e88-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH net-next 1/2] inet: remove icsk_ack.blocked
2020-09-30 12:54 ` [PATCH net-next 1/2] inet: remove icsk_ack.blocked Eric Dumazet
@ 2020-09-30 13:45 ` Soheil Hassas Yeganeh
0 siblings, 0 replies; 6+ messages in thread
From: Soheil Hassas Yeganeh @ 2020-09-30 13:45 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, netdev, Neal Cardwell, Yuchung Cheng, Eric Dumazet
On Wed, Sep 30, 2020 at 8:55 AM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> TCP has been using it to work around the possibility of tcp_delack_timer()
> finding the socket owned by user.
>
> After commit 6f458dfb4092 ("tcp: improve latencies of timer triggered events")
> we added TCP_DELACK_TIMER_DEFERRED atomic bit for more immediate recovery,
> so we can get rid of icsk_ack.blocked
>
> This frees space that following patch will reuse.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
> ---
> include/net/inet_connection_sock.h | 4 ++--
> net/dccp/timer.c | 1 -
> net/ipv4/inet_connection_sock.c | 2 +-
> net/ipv4/tcp.c | 6 ++----
> net/ipv4/tcp_output.c | 7 ++-----
> net/ipv4/tcp_timer.c | 1 -
> 6 files changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
> index dc763ca9413cc9c6279a59f9d1776cf2dbb1e853..79875f976190750819948425e63dd0309c699050 100644
> --- a/include/net/inet_connection_sock.h
> +++ b/include/net/inet_connection_sock.h
> @@ -110,7 +110,7 @@ struct inet_connection_sock {
> __u8 pending; /* ACK is pending */
> __u8 quick; /* Scheduled number of quick acks */
> __u8 pingpong; /* The session is interactive */
> - __u8 blocked; /* Delayed ACK was blocked by socket lock */
> + /* one byte hole. */
> __u32 ato; /* Predicted tick of soft clock */
> unsigned long timeout; /* Currently scheduled timeout */
> __u32 lrcvtime; /* timestamp of last received data packet */
> @@ -198,7 +198,7 @@ static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
> sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
> #endif
> } else if (what == ICSK_TIME_DACK) {
> - icsk->icsk_ack.blocked = icsk->icsk_ack.pending = 0;
> + icsk->icsk_ack.pending = 0;
> #ifdef INET_CSK_CLEAR_TIMERS
> sk_stop_timer(sk, &icsk->icsk_delack_timer);
> #endif
> diff --git a/net/dccp/timer.c b/net/dccp/timer.c
> index 927c796d76825439a35c4deb3fb2e45e4313f9b3..a934d293237366aeca87bd3c32241880639291c5 100644
> --- a/net/dccp/timer.c
> +++ b/net/dccp/timer.c
> @@ -176,7 +176,6 @@ static void dccp_delack_timer(struct timer_list *t)
> bh_lock_sock(sk);
> if (sock_owned_by_user(sk)) {
> /* Try again later. */
> - icsk->icsk_ack.blocked = 1;
> __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
> sk_reset_timer(sk, &icsk->icsk_delack_timer,
> jiffies + TCP_DELACK_MIN);
> diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> index b457dd2d6c75b2f63bc7849474ac909adb14d603..4148f5f78f313cde1e0596b9eb3696df16e3f990 100644
> --- a/net/ipv4/inet_connection_sock.c
> +++ b/net/ipv4/inet_connection_sock.c
> @@ -564,7 +564,7 @@ void inet_csk_clear_xmit_timers(struct sock *sk)
> {
> struct inet_connection_sock *icsk = inet_csk(sk);
>
> - icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
> + icsk->icsk_pending = icsk->icsk_ack.pending = 0;
>
> sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
> sk_stop_timer(sk, &icsk->icsk_delack_timer);
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 2a8bfa89a5159837e3687e4e0f8cddba7fe54899..ed2805564424a90f003eed867bbed7f5ac4ae833 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -1538,10 +1538,8 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
>
> if (inet_csk_ack_scheduled(sk)) {
> const struct inet_connection_sock *icsk = inet_csk(sk);
> - /* Delayed ACKs frequently hit locked sockets during bulk
> - * receive. */
> - if (icsk->icsk_ack.blocked ||
> - /* Once-per-two-segments ACK was not sent by tcp_input.c */
> +
> + if (/* Once-per-two-segments ACK was not sent by tcp_input.c */
> tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
> /*
> * If this read emptied read buffer, we send ACK, if
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 386978dcd318d84af486d0d1a5bb1786f4a493cf..6bd4e383030ea20441332a30e98fbda8cd90f84a 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3911,11 +3911,8 @@ void tcp_send_delayed_ack(struct sock *sk)
>
> /* Use new timeout only if there wasn't a older one earlier. */
> if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
> - /* If delack timer was blocked or is about to expire,
> - * send ACK now.
> - */
> - if (icsk->icsk_ack.blocked ||
> - time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
> + /* If delack timer is about to expire, send ACK now. */
> + if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) {
> tcp_send_ack(sk);
> return;
> }
> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
> index 0c08c420fbc21a98dedf72148ea2a6f85bf3ff7a..6c62b9ea1320d9bbd26ed86b9f41de02fee6c491 100644
> --- a/net/ipv4/tcp_timer.c
> +++ b/net/ipv4/tcp_timer.c
> @@ -331,7 +331,6 @@ static void tcp_delack_timer(struct timer_list *t)
> if (!sock_owned_by_user(sk)) {
> tcp_delack_timer_handler(sk);
> } else {
> - icsk->icsk_ack.blocked = 1;
> __NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
> /* deleguate our work to tcp_release_cb() */
> if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags))
> --
> 2.28.0.806.g8561365e88-goog
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack()
2020-09-30 12:54 ` [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack() Eric Dumazet
@ 2020-09-30 15:00 ` Soheil Hassas Yeganeh
0 siblings, 0 replies; 6+ messages in thread
From: Soheil Hassas Yeganeh @ 2020-09-30 15:00 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, netdev, Neal Cardwell, Yuchung Cheng, Eric Dumazet
On Wed, Sep 30, 2020 at 8:55 AM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> Whenever host is under very high memory pressure,
> __tcp_send_ack() skb allocation fails, and we setup
> a 200 ms (TCP_DELACK_MAX) timer before retrying.
>
> On hosts with high number of TCP sockets, we can spend
> considerable amount of cpu cycles in these attempts,
> add high pressure on various spinlocks in mm-layer,
> ultimately blocking threads attempting to free space
> from making any progress.
>
> This patch adds standard exponential backoff to avoid
> adding fuel to the fire.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
> ---
> include/net/inet_connection_sock.h | 3 ++-
> net/ipv4/tcp_output.c | 11 ++++++++---
> 2 files changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
> index 79875f976190750819948425e63dd0309c699050..7338b3865a2a3d278dc27c0167bba1b966bbda9f 100644
> --- a/include/net/inet_connection_sock.h
> +++ b/include/net/inet_connection_sock.h
> @@ -110,7 +110,7 @@ struct inet_connection_sock {
> __u8 pending; /* ACK is pending */
> __u8 quick; /* Scheduled number of quick acks */
> __u8 pingpong; /* The session is interactive */
> - /* one byte hole. */
> + __u8 retry; /* Number of attempts */
> __u32 ato; /* Predicted tick of soft clock */
> unsigned long timeout; /* Currently scheduled timeout */
> __u32 lrcvtime; /* timestamp of last received data packet */
> @@ -199,6 +199,7 @@ static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
> #endif
> } else if (what == ICSK_TIME_DACK) {
> icsk->icsk_ack.pending = 0;
> + icsk->icsk_ack.retry = 0;
> #ifdef INET_CSK_CLEAR_TIMERS
> sk_stop_timer(sk, &icsk->icsk_delack_timer);
> #endif
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 6bd4e383030ea20441332a30e98fbda8cd90f84a..bf48cd73e96787a14b6f9af8beddb1067a7cb8dc 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3941,10 +3941,15 @@ void __tcp_send_ack(struct sock *sk, u32 rcv_nxt)
> buff = alloc_skb(MAX_TCP_HEADER,
> sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN));
> if (unlikely(!buff)) {
> + struct inet_connection_sock *icsk = inet_csk(sk);
> + unsigned long delay;
> +
> + delay = TCP_DELACK_MAX << icsk->icsk_ack.retry;
> + if (delay < TCP_RTO_MAX)
> + icsk->icsk_ack.retry++;
> inet_csk_schedule_ack(sk);
> - inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
> - inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
> - TCP_DELACK_MAX, TCP_RTO_MAX);
> + icsk->icsk_ack.ato = TCP_ATO_MIN;
> + inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX);
> return;
> }
>
> --
> 2.28.0.806.g8561365e88-goog
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack()
2020-09-30 12:54 [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() Eric Dumazet
2020-09-30 12:54 ` [PATCH net-next 1/2] inet: remove icsk_ack.blocked Eric Dumazet
2020-09-30 12:54 ` [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack() Eric Dumazet
@ 2020-09-30 21:21 ` David Miller
2 siblings, 0 replies; 6+ messages in thread
From: David Miller @ 2020-09-30 21:21 UTC (permalink / raw)
To: eric.dumazet; +Cc: netdev, soheil, ncardwell, ycheng, edumazet
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 30 Sep 2020 05:54:55 -0700
> We had outages caused by repeated skb allocation failures in tcp_send_ack()
>
> It is time to add exponential backoff to reduce number of attempts.
> Before doing so, first patch removes icsk_ack.blocked to make
> room for a new field (icsk_ack.retry)
Series applied, thanks Eric.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-09-30 12:54 [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() Eric Dumazet
2020-09-30 12:54 ` [PATCH net-next 1/2] inet: remove icsk_ack.blocked Eric Dumazet
2020-09-30 13:45 ` Soheil Hassas Yeganeh
2020-09-30 12:54 ` [PATCH net-next 2/2] tcp: add exponential backoff in __tcp_send_ack() Eric Dumazet
2020-09-30 15:00 ` Soheil Hassas Yeganeh
2020-09-30 21:21 ` [PATCH net-next 0/2] tcp: exponential backoff in tcp_send_ack() David Miller
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