* [PATCH v4 net-next 14/16] tcp: new CC hook to set sending rate with rate_sample in any CA state
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Yuchung Cheng, Van Jacobson, Neal Cardwell,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Yuchung Cheng <ycheng@google.com>
This commit introduces an optional new "omnipotent" hook,
cong_control(), for congestion control modules. The cong_control()
function is called at the end of processing an ACK (i.e., after
updating sequence numbers, the SACK scoreboard, and loss
detection). At that moment we have precise delivery rate information
the congestion control module can use to control the sending behavior
(using cwnd, TSO skb size, and pacing rate) in any CA state.
This function can also be used by a congestion control that prefers
not to use the default cwnd reduction approach (i.e., the PRR
algorithm) during CA_Recovery to control the cwnd and sending rate
during loss recovery.
We take advantage of the fact that recent changes defer the
retransmission or transmission of new data (e.g. by F-RTO) in recovery
until the new tcp_cong_control() function is run.
With this commit, we only run tcp_update_pacing_rate() if the
congestion control is not using this new API. New congestion controls
which use the new API do not want the TCP stack to run the default
pacing rate calculation and overwrite whatever pacing rate they have
chosen at initialization time.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/net/tcp.h | 4 ++++
net/ipv4/tcp_cong.c | 2 +-
net/ipv4/tcp_input.c | 17 ++++++++++++++---
3 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 1aa9628..f83b7f2 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -919,6 +919,10 @@ struct tcp_congestion_ops {
u32 (*tso_segs_goal)(struct sock *sk);
/* returns the multiplier used in tcp_sndbuf_expand (optional) */
u32 (*sndbuf_expand)(struct sock *sk);
+ /* call when packets are delivered to update cwnd and pacing rate,
+ * after all the ca_state processing. (optional)
+ */
+ void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
/* get info for inet_diag (optional) */
size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 882caa4..1294af4 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -69,7 +69,7 @@ int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
int ret = 0;
/* all algorithms must implement ssthresh and cong_avoid ops */
- if (!ca->ssthresh || !ca->cong_avoid) {
+ if (!ca->ssthresh || !(ca->cong_avoid || ca->cong_control)) {
pr_err("%s does not implement required ops\n", ca->name);
return -EINVAL;
}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5af0bf3..28cfe99 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2536,6 +2536,9 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
+ if (inet_csk(sk)->icsk_ca_ops->cong_control)
+ return;
+
/* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */
if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR ||
(tp->undo_marker && tp->snd_ssthresh < TCP_INFINITE_SSTHRESH)) {
@@ -3312,8 +3315,15 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag)
* information. All transmission or retransmission are delayed afterwards.
*/
static void tcp_cong_control(struct sock *sk, u32 ack, u32 acked_sacked,
- int flag)
+ int flag, const struct rate_sample *rs)
{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+
+ if (icsk->icsk_ca_ops->cong_control) {
+ icsk->icsk_ca_ops->cong_control(sk, rs);
+ return;
+ }
+
if (tcp_in_cwnd_reduction(sk)) {
/* Reduce cwnd if state mandates */
tcp_cwnd_reduction(sk, acked_sacked, flag);
@@ -3683,7 +3693,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
delivered = tp->delivered - delivered; /* freshly ACKed or SACKed */
lost = tp->lost - lost; /* freshly marked lost */
tcp_rate_gen(sk, delivered, lost, &now, &rs);
- tcp_cong_control(sk, ack, delivered, flag);
+ tcp_cong_control(sk, ack, delivered, flag, &rs);
tcp_xmit_recovery(sk, rexmit);
return 1;
@@ -5981,7 +5991,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
} else
tcp_init_metrics(sk);
- tcp_update_pacing_rate(sk);
+ if (!inet_csk(sk)->icsk_ca_ops->cong_control)
+ tcp_update_pacing_rate(sk);
/* Prevent spurious tcp_cwnd_restart() on first data packet */
tp->lsndtime = tcp_time_stamp;
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 13/16] tcp: allow congestion control to expand send buffer differently
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Yuchung Cheng, Van Jacobson, Neal Cardwell,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Yuchung Cheng <ycheng@google.com>
Currently the TCP send buffer expands to twice cwnd, in order to allow
limited transmits in the CA_Recovery state. This assumes that cwnd
does not increase in the CA_Recovery.
For some congestion control algorithms, like the upcoming BBR module,
if the losses in recovery do not indicate congestion then we may
continue to raise cwnd multiplicatively in recovery. In such cases the
current multiplier will falsely limit the sending rate, much as if it
were limited by the application.
This commit adds an optional congestion control callback to use a
different multiplier to expand the TCP send buffer. For congestion
control modules that do not specificy this callback, TCP continues to
use the previous default of 2.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/net/tcp.h | 2 ++
net/ipv4/tcp_input.c | 4 +++-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3492041..1aa9628 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -917,6 +917,8 @@ struct tcp_congestion_ops {
void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
/* suggest number of segments for each skb to transmit (optional) */
u32 (*tso_segs_goal)(struct sock *sk);
+ /* returns the multiplier used in tcp_sndbuf_expand (optional) */
+ u32 (*sndbuf_expand)(struct sock *sk);
/* get info for inet_diag (optional) */
size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 17de77d..5af0bf3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -289,6 +289,7 @@ static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr
static void tcp_sndbuf_expand(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
+ const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
int sndmem, per_mss;
u32 nr_segs;
@@ -309,7 +310,8 @@ static void tcp_sndbuf_expand(struct sock *sk)
* Cubic needs 1.7 factor, rounded to 2 to include
* extra cushion (application might react slowly to POLLOUT)
*/
- sndmem = 2 * nr_segs * per_mss;
+ sndmem = ca_ops->sndbuf_expand ? ca_ops->sndbuf_expand(sk) : 2;
+ sndmem *= nr_segs * per_mss;
if (sk->sk_sndbuf < sndmem)
sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 12/16] tcp: export tcp_mss_to_mtu() for congestion control modules
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
Export tcp_mss_to_mtu(), so that congestion control modules can use
this to help calculate a pacing rate.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
net/ipv4/tcp_output.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0bf3d48..7d025a7 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1362,6 +1362,7 @@ int tcp_mss_to_mtu(struct sock *sk, int mss)
}
return mtu;
}
+EXPORT_SYMBOL(tcp_mss_to_mtu);
/* MTU probing init per socket */
void tcp_mtup_init(struct sock *sk)
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 11/16] tcp: export tcp_tso_autosize() and parameterize minimum number of TSO segments
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
To allow congestion control modules to use the default TSO auto-sizing
algorithm as one of the ingredients in their own decision about TSO sizing:
1) Export tcp_tso_autosize() so that CC modules can use it.
2) Change tcp_tso_autosize() to allow callers to specify a minimum
number of segments per TSO skb, in case the congestion control
module has a different notion of the best floor for TSO skbs for
the connection right now. For very low-rate paths or policed
connections it can be appropriate to use smaller TSO skbs.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/net/tcp.h | 2 ++
net/ipv4/tcp_output.c | 9 ++++++---
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index f8f581f..3492041 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -533,6 +533,8 @@ __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
#endif
/* tcp_output.c */
+u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
+ int min_tso_segs);
void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
int nonagle);
bool tcp_may_send_now(struct sock *sk);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0137956..0bf3d48 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1549,7 +1549,8 @@ static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp,
/* Return how many segs we'd like on a TSO packet,
* to send one TSO packet per ms
*/
-static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now)
+u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
+ int min_tso_segs)
{
u32 bytes, segs;
@@ -1561,10 +1562,11 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now)
* This preserves ACK clocking and is consistent
* with tcp_tso_should_defer() heuristic.
*/
- segs = max_t(u32, bytes / mss_now, sysctl_tcp_min_tso_segs);
+ segs = max_t(u32, bytes / mss_now, min_tso_segs);
return min_t(u32, segs, sk->sk_gso_max_segs);
}
+EXPORT_SYMBOL(tcp_tso_autosize);
/* Return the number of segments we want in the skb we are transmitting.
* See if congestion control module wants to decide; otherwise, autosize.
@@ -1574,7 +1576,8 @@ static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now)
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0;
- return tso_segs ? : tcp_tso_autosize(sk, mss_now);
+ return tso_segs ? :
+ tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs);
}
/* Returns the portion of skb which can be sent right away */
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 10/16] tcp: allow congestion control module to request TSO skb segment count
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
Add the tso_segs_goal() function in tcp_congestion_ops to allow the
congestion control module to specify the number of segments that
should be in a TSO skb sent by tcp_write_xmit() and
tcp_xmit_retransmit_queue(). The congestion control module can either
request a particular number of segments in TSO skb that we transmit,
or return 0 if it doesn't care.
This allows the upcoming BBR congestion control module to select small
TSO skb sizes if the module detects that the bottleneck bandwidth is
very low, or that the connection is policed to a low rate.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/net/tcp.h | 2 ++
net/ipv4/tcp_output.c | 15 +++++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index a69ed7f..f8f581f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -913,6 +913,8 @@ struct tcp_congestion_ops {
u32 (*undo_cwnd)(struct sock *sk);
/* hook for packet ack accounting (optional) */
void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
+ /* suggest number of segments for each skb to transmit (optional) */
+ u32 (*tso_segs_goal)(struct sock *sk);
/* get info for inet_diag (optional) */
size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
union tcp_cc_info *info);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index e02c8eb..0137956 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1566,6 +1566,17 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now)
return min_t(u32, segs, sk->sk_gso_max_segs);
}
+/* Return the number of segments we want in the skb we are transmitting.
+ * See if congestion control module wants to decide; otherwise, autosize.
+ */
+static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now)
+{
+ const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
+ u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0;
+
+ return tso_segs ? : tcp_tso_autosize(sk, mss_now);
+}
+
/* Returns the portion of skb which can be sent right away */
static unsigned int tcp_mss_split_point(const struct sock *sk,
const struct sk_buff *skb,
@@ -2061,7 +2072,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
}
}
- max_segs = tcp_tso_autosize(sk, mss_now);
+ max_segs = tcp_tso_segs(sk, mss_now);
while ((skb = tcp_send_head(sk))) {
unsigned int limit;
@@ -2778,7 +2789,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
last_lost = tp->snd_una;
}
- max_segs = tcp_tso_autosize(sk, tcp_current_mss(sk));
+ max_segs = tcp_tso_segs(sk, tcp_current_mss(sk));
tcp_for_write_queue_from(skb, sk) {
__u8 sacked;
int segs;
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 09/16] tcp: export data delivery rate
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Yuchung Cheng, Van Jacobson, Neal Cardwell,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Yuchung Cheng <ycheng@google.com>
This commit export two new fields in struct tcp_info:
tcpi_delivery_rate: The most recent goodput, as measured by
tcp_rate_gen(). If the socket is limited by the sending
application (e.g., no data to send), it reports the highest
measurement instead of the most recent. The unit is bytes per
second (like other rate fields in tcp_info).
tcpi_delivery_rate_app_limited: A boolean indicating if the goodput
was measured when the socket's throughput was limited by the
sending application.
This delivery rate information can be useful for applications that
want to know the current throughput the TCP connection is seeing,
e.g. adaptive bitrate video streaming. It can also be very useful for
debugging or troubleshooting.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/tcp.h | 5 ++++-
include/uapi/linux/tcp.h | 3 +++
net/ipv4/tcp.c | 11 ++++++++++-
net/ipv4/tcp_rate.c | 12 +++++++++++-
4 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index fdcd00f..a17ae7b 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -213,7 +213,8 @@ struct tcp_sock {
u8 reord; /* reordering detected */
} rack;
u16 advmss; /* Advertised MSS */
- u8 unused;
+ u8 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */
+ unused:7;
u8 nonagle : 4,/* Disable Nagle algorithm? */
thin_lto : 1,/* Use linear timeouts for thin streams */
thin_dupack : 1,/* Fast retransmit on first dupack */
@@ -271,6 +272,8 @@ struct tcp_sock {
u32 app_limited; /* limited until "delivered" reaches this val */
struct skb_mstamp first_tx_mstamp; /* start of window send phase */
struct skb_mstamp delivered_mstamp; /* time we reached "delivered" */
+ u32 rate_delivered; /* saved rate sample: packets delivered */
+ u32 rate_interval_us; /* saved rate sample: time elapsed */
u32 rcv_wnd; /* Current receiver window */
u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 482898f..73ac0db 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -167,6 +167,7 @@ struct tcp_info {
__u8 tcpi_backoff;
__u8 tcpi_options;
__u8 tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
+ __u8 tcpi_delivery_rate_app_limited:1;
__u32 tcpi_rto;
__u32 tcpi_ato;
@@ -211,6 +212,8 @@ struct tcp_info {
__u32 tcpi_min_rtt;
__u32 tcpi_data_segs_in; /* RFC4898 tcpEStatsDataSegsIn */
__u32 tcpi_data_segs_out; /* RFC4898 tcpEStatsDataSegsOut */
+
+ __u64 tcpi_delivery_rate;
};
/* for TCP_MD5SIG socket option */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c187552..cece376 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2695,7 +2695,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
{
const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
const struct inet_connection_sock *icsk = inet_csk(sk);
- u32 now = tcp_time_stamp;
+ u32 now = tcp_time_stamp, intv;
unsigned int start;
int notsent_bytes;
u64 rate64;
@@ -2785,6 +2785,15 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
info->tcpi_min_rtt = tcp_min_rtt(tp);
info->tcpi_data_segs_in = tp->data_segs_in;
info->tcpi_data_segs_out = tp->data_segs_out;
+
+ info->tcpi_delivery_rate_app_limited = tp->rate_app_limited ? 1 : 0;
+ rate = READ_ONCE(tp->rate_delivered);
+ intv = READ_ONCE(tp->rate_interval_us);
+ if (rate && intv) {
+ rate64 = (u64)rate * tp->mss_cache * USEC_PER_SEC;
+ do_div(rate64, intv);
+ put_unaligned(rate64, &info->tcpi_delivery_rate);
+ }
}
EXPORT_SYMBOL_GPL(tcp_get_info);
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index 52ff84b..9be1581 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -149,12 +149,22 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
* for connections suffer heavy or prolonged losses.
*/
if (unlikely(rs->interval_us < tcp_min_rtt(tp))) {
- rs->interval_us = -1;
if (!rs->is_retrans)
pr_debug("tcp rate: %ld %d %u %u %u\n",
rs->interval_us, rs->delivered,
inet_csk(sk)->icsk_ca_state,
tp->rx_opt.sack_ok, tcp_min_rtt(tp));
+ rs->interval_us = -1;
+ return;
+ }
+
+ /* Record the last non-app-limited or the highest app-limited bw */
+ if (!rs->is_app_limited ||
+ ((u64)rs->delivered * tp->rate_interval_us >=
+ (u64)tp->rate_delivered * rs->interval_us)) {
+ tp->rate_delivered = rs->delivered;
+ tp->rate_interval_us = rs->interval_us;
+ tp->rate_app_limited = rs->is_app_limited;
}
}
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 07/16] tcp: track data delivery rate for a TCP connection
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Yuchung Cheng, Van Jacobson, Neal Cardwell,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Yuchung Cheng <ycheng@google.com>
This patch generates data delivery rate (throughput) samples on a
per-ACK basis. These rate samples can be used by congestion control
modules, and specifically will be used by TCP BBR in later patches in
this series.
Key state:
tp->delivered: Tracks the total number of data packets (original or not)
delivered so far. This is an already-existing field.
tp->delivered_mstamp: the last time tp->delivered was updated.
Algorithm:
A rate sample is calculated as (d1 - d0)/(t1 - t0) on a per-ACK basis:
d1: the current tp->delivered after processing the ACK
t1: the current time after processing the ACK
d0: the prior tp->delivered when the acked skb was transmitted
t0: the prior tp->delivered_mstamp when the acked skb was transmitted
When an skb is transmitted, we snapshot d0 and t0 in its control
block in tcp_rate_skb_sent().
When an ACK arrives, it may SACK and ACK some skbs. For each SACKed
or ACKed skb, tcp_rate_skb_delivered() updates the rate_sample struct
to reflect the latest (d0, t0).
Finally, tcp_rate_gen() generates a rate sample by storing
(d1 - d0) in rs->delivered and (t1 - t0) in rs->interval_us.
One caveat: if an skb was sent with no packets in flight, then
tp->delivered_mstamp may be either invalid (if the connection is
starting) or outdated (if the connection was idle). In that case,
we'll re-stamp tp->delivered_mstamp.
At first glance it seems t0 should always be the time when an skb was
transmitted, but actually this could over-estimate the rate due to
phase mismatch between transmit and ACK events. To track the delivery
rate, we ensure that if packets are in flight then t0 and and t1 are
times at which packets were marked delivered.
If the initial and final RTTs are different then one may be corrupted
by some sort of noise. The noise we see most often is sending gaps
caused by delayed, compressed, or stretched acks. This either affects
both RTTs equally or artificially reduces the final RTT. We approach
this by recording the info we need to compute the initial RTT
(duration of the "send phase" of the window) when we recorded the
associated inflight. Then, for a filter to avoid bandwidth
overestimates, we generalize the per-sample bandwidth computation
from:
bw = delivered / ack_phase_rtt
to the following:
bw = delivered / max(send_phase_rtt, ack_phase_rtt)
In large-scale experiments, this filtering approach incorporating
send_phase_rtt is effective at avoiding bandwidth overestimates due to
ACK compression or stretched ACKs.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/tcp.h | 2 +
include/net/tcp.h | 35 +++++++++++-
net/ipv4/Makefile | 2 +-
net/ipv4/tcp_input.c | 46 +++++++++++-----
net/ipv4/tcp_output.c | 4 ++
net/ipv4/tcp_rate.c | 149 ++++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 222 insertions(+), 16 deletions(-)
create mode 100644 net/ipv4/tcp_rate.c
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 38590fb..c50e6ae 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -268,6 +268,8 @@ struct tcp_sock {
u32 prr_out; /* Total number of pkts sent during Recovery. */
u32 delivered; /* Total data packets delivered incl. rexmits */
u32 lost; /* Total data packets lost incl. rexmits */
+ struct skb_mstamp first_tx_mstamp; /* start of window send phase */
+ struct skb_mstamp delivered_mstamp; /* time we reached "delivered" */
u32 rcv_wnd; /* Current receiver window */
u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2f1648a..b261c89 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -763,8 +763,14 @@ struct tcp_skb_cb {
__u32 ack_seq; /* Sequence number ACK'd */
union {
struct {
- /* There is space for up to 20 bytes */
+ /* There is space for up to 24 bytes */
__u32 in_flight;/* Bytes in flight when packet sent */
+ /* pkts S/ACKed so far upon tx of skb, incl retrans: */
+ __u32 delivered;
+ /* start of send pipeline phase */
+ struct skb_mstamp first_tx_mstamp;
+ /* when we reached the "delivered" count */
+ struct skb_mstamp delivered_mstamp;
} tx; /* only used for outgoing skbs */
union {
struct inet_skb_parm h4;
@@ -860,6 +866,26 @@ struct ack_sample {
u32 in_flight;
};
+/* A rate sample measures the number of (original/retransmitted) data
+ * packets delivered "delivered" over an interval of time "interval_us".
+ * The tcp_rate.c code fills in the rate sample, and congestion
+ * control modules that define a cong_control function to run at the end
+ * of ACK processing can optionally chose to consult this sample when
+ * setting cwnd and pacing rate.
+ * A sample is invalid if "delivered" or "interval_us" is negative.
+ */
+struct rate_sample {
+ struct skb_mstamp prior_mstamp; /* starting timestamp for interval */
+ u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
+ s32 delivered; /* number of packets delivered over interval */
+ long interval_us; /* time for tp->delivered to incr "delivered" */
+ long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
+ int losses; /* number of packets marked lost upon ACK */
+ u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
+ u32 prior_in_flight; /* in flight before this ACK */
+ bool is_retrans; /* is sample from retransmission? */
+};
+
struct tcp_congestion_ops {
struct list_head list;
u32 key;
@@ -946,6 +972,13 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
icsk->icsk_ca_ops->cwnd_event(sk, event);
}
+/* From tcp_rate.c */
+void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
+void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
+ struct rate_sample *rs);
+void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
+ struct skb_mstamp *now, struct rate_sample *rs);
+
/* These functions determine how the current flow behaves in respect of SACK
* handling. SACK is negotiated with the peer, and therefore it can vary
* between different flows.
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 24629b6..9cfff1a 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -8,7 +8,7 @@ obj-y := route.o inetpeer.o protocol.o \
inet_timewait_sock.o inet_connection_sock.o \
tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
tcp_minisocks.o tcp_cong.o tcp_metrics.o tcp_fastopen.o \
- tcp_recovery.o \
+ tcp_rate.o tcp_recovery.o \
tcp_offload.o datagram.o raw.o udp.o udplite.o \
udp_offload.o arp.o icmp.o devinet.o af_inet.o igmp.o \
fib_frontend.o fib_semantics.o fib_trie.o \
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 024b579..17de77d 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1112,6 +1112,7 @@ struct tcp_sacktag_state {
*/
struct skb_mstamp first_sackt;
struct skb_mstamp last_sackt;
+ struct rate_sample *rate;
int flag;
};
@@ -1279,6 +1280,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
tcp_sacktag_one(sk, state, TCP_SKB_CB(skb)->sacked,
start_seq, end_seq, dup_sack, pcount,
&skb->skb_mstamp);
+ tcp_rate_skb_delivered(sk, skb, state->rate);
if (skb == tp->lost_skb_hint)
tp->lost_cnt_hint += pcount;
@@ -1329,6 +1331,9 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
tcp_advance_highest_sack(sk, skb);
tcp_skb_collapse_tstamp(prev, skb);
+ if (unlikely(TCP_SKB_CB(prev)->tx.delivered_mstamp.v64))
+ TCP_SKB_CB(prev)->tx.delivered_mstamp.v64 = 0;
+
tcp_unlink_write_queue(skb, sk);
sk_wmem_free_skb(sk, skb);
@@ -1558,6 +1563,7 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk,
dup_sack,
tcp_skb_pcount(skb),
&skb->skb_mstamp);
+ tcp_rate_skb_delivered(sk, skb, state->rate);
if (!before(TCP_SKB_CB(skb)->seq,
tcp_highest_sack_seq(tp)))
@@ -1640,8 +1646,10 @@ tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
found_dup_sack = tcp_check_dsack(sk, ack_skb, sp_wire,
num_sacks, prior_snd_una);
- if (found_dup_sack)
+ if (found_dup_sack) {
state->flag |= FLAG_DSACKING_ACK;
+ tp->delivered++; /* A spurious retransmission is delivered */
+ }
/* Eliminate too old ACKs, but take into
* account more or less fresh ones, they can
@@ -3071,10 +3079,11 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb,
*/
static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
u32 prior_snd_una, int *acked,
- struct tcp_sacktag_state *sack)
+ struct tcp_sacktag_state *sack,
+ struct skb_mstamp *now)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
- struct skb_mstamp first_ackt, last_ackt, now;
+ struct skb_mstamp first_ackt, last_ackt;
struct tcp_sock *tp = tcp_sk(sk);
u32 prior_sacked = tp->sacked_out;
u32 reord = tp->packets_out;
@@ -3106,7 +3115,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
acked_pcount = tcp_tso_acked(sk, skb);
if (!acked_pcount)
break;
-
fully_acked = false;
} else {
/* Speedup tcp_unlink_write_queue() and next loop */
@@ -3142,6 +3150,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
tp->packets_out -= acked_pcount;
pkts_acked += acked_pcount;
+ tcp_rate_skb_delivered(sk, skb, sack->rate);
/* Initial outgoing SYN's get put onto the write_queue
* just like anything else we transmit. It is not
@@ -3174,16 +3183,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
flag |= FLAG_SACK_RENEGING;
- skb_mstamp_get(&now);
if (likely(first_ackt.v64) && !(flag & FLAG_RETRANS_DATA_ACKED)) {
- seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt);
- ca_rtt_us = skb_mstamp_us_delta(&now, &last_ackt);
+ seq_rtt_us = skb_mstamp_us_delta(now, &first_ackt);
+ ca_rtt_us = skb_mstamp_us_delta(now, &last_ackt);
}
if (sack->first_sackt.v64) {
- sack_rtt_us = skb_mstamp_us_delta(&now, &sack->first_sackt);
- ca_rtt_us = skb_mstamp_us_delta(&now, &sack->last_sackt);
+ sack_rtt_us = skb_mstamp_us_delta(now, &sack->first_sackt);
+ ca_rtt_us = skb_mstamp_us_delta(now, &sack->last_sackt);
}
-
+ sack->rate->rtt_us = ca_rtt_us; /* RTT of last (S)ACKed packet, or -1 */
rtt_update = tcp_ack_update_rtt(sk, flag, seq_rtt_us, sack_rtt_us,
ca_rtt_us);
@@ -3211,7 +3219,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
tp->fackets_out -= min(pkts_acked, tp->fackets_out);
} else if (skb && rtt_update && sack_rtt_us >= 0 &&
- sack_rtt_us > skb_mstamp_us_delta(&now, &skb->skb_mstamp)) {
+ sack_rtt_us > skb_mstamp_us_delta(now, &skb->skb_mstamp)) {
/* Do not re-arm RTO if the sack RTT is measured from data sent
* after when the head was last (re)transmitted. Otherwise the
* timeout may continue to extend in loss recovery.
@@ -3548,17 +3556,21 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_sacktag_state sack_state;
+ struct rate_sample rs = { .prior_delivered = 0 };
u32 prior_snd_una = tp->snd_una;
u32 ack_seq = TCP_SKB_CB(skb)->seq;
u32 ack = TCP_SKB_CB(skb)->ack_seq;
bool is_dupack = false;
u32 prior_fackets;
int prior_packets = tp->packets_out;
- u32 prior_delivered = tp->delivered;
+ u32 delivered = tp->delivered;
+ u32 lost = tp->lost;
int acked = 0; /* Number of packets newly acked */
int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
+ struct skb_mstamp now;
sack_state.first_sackt.v64 = 0;
+ sack_state.rate = &rs;
/* We very likely will need to access write queue head. */
prefetchw(sk->sk_write_queue.next);
@@ -3581,6 +3593,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (after(ack, tp->snd_nxt))
goto invalid_ack;
+ skb_mstamp_get(&now);
+
if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
tcp_rearm_rto(sk);
@@ -3591,6 +3605,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
}
prior_fackets = tp->fackets_out;
+ rs.prior_in_flight = tcp_packets_in_flight(tp);
/* ts_recent update must be made after we are sure that the packet
* is in window.
@@ -3646,7 +3661,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
/* See if we can take anything off of the retransmit queue. */
flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una, &acked,
- &sack_state);
+ &sack_state, &now);
if (tcp_ack_is_dubious(sk, flag)) {
is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
@@ -3663,7 +3678,10 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (icsk->icsk_pending == ICSK_TIME_RETRANS)
tcp_schedule_loss_probe(sk);
- tcp_cong_control(sk, ack, tp->delivered - prior_delivered, flag);
+ delivered = tp->delivered - delivered; /* freshly ACKed or SACKed */
+ lost = tp->lost - lost; /* freshly marked lost */
+ tcp_rate_gen(sk, delivered, lost, &now, &rs);
+ tcp_cong_control(sk, ack, delivered, flag);
tcp_xmit_recovery(sk, rexmit);
return 1;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8b45794..e02c8eb 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -918,6 +918,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
skb_mstamp_get(&skb->skb_mstamp);
TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
- tp->snd_una;
+ tcp_rate_skb_sent(sk, skb);
if (unlikely(skb_cloned(skb)))
skb = pskb_copy(skb, gfp_mask);
@@ -1213,6 +1214,9 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
tcp_set_skb_tso_segs(skb, mss_now);
tcp_set_skb_tso_segs(buff, mss_now);
+ /* Update delivered info for the new segment */
+ TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx;
+
/* If this packet has been sent out already, we must
* adjust the various packet counters.
*/
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
new file mode 100644
index 0000000..1daed6a
--- /dev/null
+++ b/net/ipv4/tcp_rate.c
@@ -0,0 +1,149 @@
+#include <net/tcp.h>
+
+/* The bandwidth estimator estimates the rate at which the network
+ * can currently deliver outbound data packets for this flow. At a high
+ * level, it operates by taking a delivery rate sample for each ACK.
+ *
+ * A rate sample records the rate at which the network delivered packets
+ * for this flow, calculated over the time interval between the transmission
+ * of a data packet and the acknowledgment of that packet.
+ *
+ * Specifically, over the interval between each transmit and corresponding ACK,
+ * the estimator generates a delivery rate sample. Typically it uses the rate
+ * at which packets were acknowledged. However, the approach of using only the
+ * acknowledgment rate faces a challenge under the prevalent ACK decimation or
+ * compression: packets can temporarily appear to be delivered much quicker
+ * than the bottleneck rate. Since it is physically impossible to do that in a
+ * sustained fashion, when the estimator notices that the ACK rate is faster
+ * than the transmit rate, it uses the latter:
+ *
+ * send_rate = #pkts_delivered/(last_snd_time - first_snd_time)
+ * ack_rate = #pkts_delivered/(last_ack_time - first_ack_time)
+ * bw = min(send_rate, ack_rate)
+ *
+ * Notice the estimator essentially estimates the goodput, not always the
+ * network bottleneck link rate when the sending or receiving is limited by
+ * other factors like applications or receiver window limits. The estimator
+ * deliberately avoids using the inter-packet spacing approach because that
+ * approach requires a large number of samples and sophisticated filtering.
+ */
+
+
+/* Snapshot the current delivery information in the skb, to generate
+ * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
+ */
+void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ /* In general we need to start delivery rate samples from the
+ * time we received the most recent ACK, to ensure we include
+ * the full time the network needs to deliver all in-flight
+ * packets. If there are no packets in flight yet, then we
+ * know that any ACKs after now indicate that the network was
+ * able to deliver those packets completely in the sampling
+ * interval between now and the next ACK.
+ *
+ * Note that we use packets_out instead of tcp_packets_in_flight(tp)
+ * because the latter is a guess based on RTO and loss-marking
+ * heuristics. We don't want spurious RTOs or loss markings to cause
+ * a spuriously small time interval, causing a spuriously high
+ * bandwidth estimate.
+ */
+ if (!tp->packets_out) {
+ tp->first_tx_mstamp = skb->skb_mstamp;
+ tp->delivered_mstamp = skb->skb_mstamp;
+ }
+
+ TCP_SKB_CB(skb)->tx.first_tx_mstamp = tp->first_tx_mstamp;
+ TCP_SKB_CB(skb)->tx.delivered_mstamp = tp->delivered_mstamp;
+ TCP_SKB_CB(skb)->tx.delivered = tp->delivered;
+}
+
+/* When an skb is sacked or acked, we fill in the rate sample with the (prior)
+ * delivery information when the skb was last transmitted.
+ *
+ * If an ACK (s)acks multiple skbs (e.g., stretched-acks), this function is
+ * called multiple times. We favor the information from the most recently
+ * sent skb, i.e., the skb with the highest prior_delivered count.
+ */
+void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
+ struct rate_sample *rs)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_skb_cb *scb = TCP_SKB_CB(skb);
+
+ if (!scb->tx.delivered_mstamp.v64)
+ return;
+
+ if (!rs->prior_delivered ||
+ after(scb->tx.delivered, rs->prior_delivered)) {
+ rs->prior_delivered = scb->tx.delivered;
+ rs->prior_mstamp = scb->tx.delivered_mstamp;
+ rs->is_retrans = scb->sacked & TCPCB_RETRANS;
+
+ /* Find the duration of the "send phase" of this window: */
+ rs->interval_us = skb_mstamp_us_delta(
+ &skb->skb_mstamp,
+ &scb->tx.first_tx_mstamp);
+
+ /* Record send time of most recently ACKed packet: */
+ tp->first_tx_mstamp = skb->skb_mstamp;
+ }
+ /* Mark off the skb delivered once it's sacked to avoid being
+ * used again when it's cumulatively acked. For acked packets
+ * we don't need to reset since it'll be freed soon.
+ */
+ if (scb->sacked & TCPCB_SACKED_ACKED)
+ scb->tx.delivered_mstamp.v64 = 0;
+}
+
+/* Update the connection delivery information and generate a rate sample. */
+void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
+ struct skb_mstamp *now, struct rate_sample *rs)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 snd_us, ack_us;
+
+ /* TODO: there are multiple places throughout tcp_ack() to get
+ * current time. Refactor the code using a new "tcp_acktag_state"
+ * to carry current time, flags, stats like "tcp_sacktag_state".
+ */
+ if (delivered)
+ tp->delivered_mstamp = *now;
+
+ rs->acked_sacked = delivered; /* freshly ACKed or SACKed */
+ rs->losses = lost; /* freshly marked lost */
+ /* Return an invalid sample if no timing information is available. */
+ if (!rs->prior_mstamp.v64) {
+ rs->delivered = -1;
+ rs->interval_us = -1;
+ return;
+ }
+ rs->delivered = tp->delivered - rs->prior_delivered;
+
+ /* Model sending data and receiving ACKs as separate pipeline phases
+ * for a window. Usually the ACK phase is longer, but with ACK
+ * compression the send phase can be longer. To be safe we use the
+ * longer phase.
+ */
+ snd_us = rs->interval_us; /* send phase */
+ ack_us = skb_mstamp_us_delta(now, &rs->prior_mstamp); /* ack phase */
+ rs->interval_us = max(snd_us, ack_us);
+
+ /* Normally we expect interval_us >= min-rtt.
+ * Note that rate may still be over-estimated when a spuriously
+ * retransmistted skb was first (s)acked because "interval_us"
+ * is under-estimated (up to an RTT). However continuously
+ * measuring the delivery rate during loss recovery is crucial
+ * for connections suffer heavy or prolonged losses.
+ */
+ if (unlikely(rs->interval_us < tcp_min_rtt(tp))) {
+ rs->interval_us = -1;
+ if (!rs->is_retrans)
+ pr_debug("tcp rate: %ld %d %u %u %u\n",
+ rs->interval_us, rs->delivered,
+ inet_csk(sk)->icsk_ca_state,
+ tp->rx_opt.sack_ok, tcp_min_rtt(tp));
+ }
+}
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 08/16] tcp: track application-limited rate samples
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Soheil Hassas Yeganeh, Van Jacobson, Neal Cardwell,
Yuchung Cheng, Nandita Dukkipati, Eric Dumazet
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Soheil Hassas Yeganeh <soheil@google.com>
This commit adds code to track whether the delivery rate represented
by each rate_sample was limited by the application.
Upon each transmit, we store in the is_app_limited field in the skb a
boolean bit indicating whether there is a known "bubble in the pipe":
a point in the rate sample interval where the sender was
application-limited, and did not transmit even though the cwnd and
pacing rate allowed it.
This logic marks the flow app-limited on a write if *all* of the
following are true:
1) There is less than 1 MSS of unsent data in the write queue
available to transmit.
2) There is no packet in the sender's queues (e.g. in fq or the NIC
tx queue).
3) The connection is not limited by cwnd.
4) There are no lost packets to retransmit.
The tcp_rate_check_app_limited() code in tcp_rate.c determines whether
the connection is application-limited at the moment. If the flow is
application-limited, it sets the tp->app_limited field. If the flow is
application-limited then that means there is effectively a "bubble" of
silence in the pipe now, and this silence will be reflected in a lower
bandwidth sample for any rate samples from now until we get an ACK
indicating this bubble has exited the pipe: specifically, until we get
an ACK for the next packet we transmit.
When we send every skb we record in scb->tx.is_app_limited whether the
resulting rate sample will be application-limited.
The code in tcp_rate_gen() checks to see when it is safe to mark all
known application-limited bubbles of silence as having exited the
pipe. It does this by checking to see when the delivered count moves
past the tp->app_limited marker. At this point it zeroes the
tp->app_limited marker, as all known bubbles are out of the pipe.
We make room for the tx.is_app_limited bit in the skb by borrowing a
bit from the in_flight field used by NV to record the number of bytes
in flight. The receive window in the TCP header is 16 bits, and the
max receive window scaling shift factor is 14 (RFC 1323). So the max
receive window offered by the TCP protocol is 2^(16+14) = 2^30. So we
only need 30 bits for the tx.in_flight used by NV.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/tcp.h | 1 +
include/net/tcp.h | 6 +++++-
net/ipv4/tcp.c | 8 ++++++++
net/ipv4/tcp_minisocks.c | 3 +++
net/ipv4/tcp_rate.c | 29 ++++++++++++++++++++++++++++-
5 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c50e6ae..fdcd00f 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -268,6 +268,7 @@ struct tcp_sock {
u32 prr_out; /* Total number of pkts sent during Recovery. */
u32 delivered; /* Total data packets delivered incl. rexmits */
u32 lost; /* Total data packets lost incl. rexmits */
+ u32 app_limited; /* limited until "delivered" reaches this val */
struct skb_mstamp first_tx_mstamp; /* start of window send phase */
struct skb_mstamp delivered_mstamp; /* time we reached "delivered" */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index b261c89..a69ed7f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -764,7 +764,9 @@ struct tcp_skb_cb {
union {
struct {
/* There is space for up to 24 bytes */
- __u32 in_flight;/* Bytes in flight when packet sent */
+ __u32 in_flight:30,/* Bytes in flight at transmit */
+ is_app_limited:1, /* cwnd not fully used? */
+ unused:1;
/* pkts S/ACKed so far upon tx of skb, incl retrans: */
__u32 delivered;
/* start of send pipeline phase */
@@ -883,6 +885,7 @@ struct rate_sample {
int losses; /* number of packets marked lost upon ACK */
u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
u32 prior_in_flight; /* in flight before this ACK */
+ bool is_app_limited; /* is sample from packet with bubble in pipe? */
bool is_retrans; /* is sample from retransmission? */
};
@@ -978,6 +981,7 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
struct rate_sample *rs);
void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
struct skb_mstamp *now, struct rate_sample *rs);
+void tcp_rate_check_app_limited(struct sock *sk);
/* These functions determine how the current flow behaves in respect of SACK
* handling. SACK is negotiated with the peer, and therefore it can vary
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9d1ae18..c187552 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -396,6 +396,9 @@ void tcp_init_sock(struct sock *sk)
*/
tp->snd_cwnd = TCP_INIT_CWND;
+ /* There's a bubble in the pipe until at least the first ACK. */
+ tp->app_limited = ~0U;
+
/* See draft-stevens-tcpca-spec-01 for discussion of the
* initialization of these values.
*/
@@ -1014,6 +1017,9 @@ int tcp_sendpage(struct sock *sk, struct page *page, int offset,
flags);
lock_sock(sk);
+
+ tcp_rate_check_app_limited(sk); /* is sending application-limited? */
+
res = do_tcp_sendpages(sk, page, offset, size, flags);
release_sock(sk);
return res;
@@ -1101,6 +1107,8 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+ tcp_rate_check_app_limited(sk); /* is sending application-limited? */
+
/* Wait for a connection to finish. One exception is TCP Fast Open
* (passive side) where data is allowed to be sent before a connection
* is fully established.
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 5689471..6234eba 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -487,6 +487,9 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->snd_cwnd = TCP_INIT_CWND;
newtp->snd_cwnd_cnt = 0;
+ /* There's a bubble in the pipe until at least the first ACK. */
+ newtp->app_limited = ~0U;
+
tcp_init_xmit_timers(newsk);
newtp->write_seq = newtp->pushed_seq = treq->snt_isn + 1;
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index 1daed6a..52ff84b 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -26,9 +26,13 @@
* other factors like applications or receiver window limits. The estimator
* deliberately avoids using the inter-packet spacing approach because that
* approach requires a large number of samples and sophisticated filtering.
+ *
+ * TCP flows can often be application-limited in request/response workloads.
+ * The estimator marks a bandwidth sample as application-limited if there
+ * was some moment during the sampled window of packets when there was no data
+ * ready to send in the write queue.
*/
-
/* Snapshot the current delivery information in the skb, to generate
* a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered().
*/
@@ -58,6 +62,7 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb)
TCP_SKB_CB(skb)->tx.first_tx_mstamp = tp->first_tx_mstamp;
TCP_SKB_CB(skb)->tx.delivered_mstamp = tp->delivered_mstamp;
TCP_SKB_CB(skb)->tx.delivered = tp->delivered;
+ TCP_SKB_CB(skb)->tx.is_app_limited = tp->app_limited ? 1 : 0;
}
/* When an skb is sacked or acked, we fill in the rate sample with the (prior)
@@ -80,6 +85,7 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
after(scb->tx.delivered, rs->prior_delivered)) {
rs->prior_delivered = scb->tx.delivered;
rs->prior_mstamp = scb->tx.delivered_mstamp;
+ rs->is_app_limited = scb->tx.is_app_limited;
rs->is_retrans = scb->sacked & TCPCB_RETRANS;
/* Find the duration of the "send phase" of this window: */
@@ -105,6 +111,10 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
struct tcp_sock *tp = tcp_sk(sk);
u32 snd_us, ack_us;
+ /* Clear app limited if bubble is acked and gone. */
+ if (tp->app_limited && after(tp->delivered, tp->app_limited))
+ tp->app_limited = 0;
+
/* TODO: there are multiple places throughout tcp_ack() to get
* current time. Refactor the code using a new "tcp_acktag_state"
* to carry current time, flags, stats like "tcp_sacktag_state".
@@ -147,3 +157,20 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
tp->rx_opt.sack_ok, tcp_min_rtt(tp));
}
}
+
+/* If a gap is detected between sends, mark the socket application-limited. */
+void tcp_rate_check_app_limited(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ if (/* We have less than one packet to send. */
+ tp->write_seq - tp->snd_nxt < tp->mss_cache &&
+ /* Nothing in sending host's qdisc queues or NIC tx queue. */
+ sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1) &&
+ /* We are not limited by CWND. */
+ tcp_packets_in_flight(tp) < tp->snd_cwnd &&
+ /* All lost packets have been retransmitted. */
+ tp->lost_out <= tp->retrans_out)
+ tp->app_limited =
+ (tp->delivered + tcp_packets_in_flight(tp)) ? : 1;
+}
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 06/16] tcp: count packets marked lost for a TCP connection
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
Count the number of packets that a TCP connection marks lost.
Congestion control modules can use this loss rate information for more
intelligent decisions about how fast to send.
Specifically, this is used in TCP BBR policer detection. BBR uses a
high packet loss rate as one signal in its policer detection and
policer bandwidth estimation algorithm.
The BBR policer detection algorithm cannot simply track retransmits,
because a retransmit can be (and often is) an indicator of packets
lost long, long ago. This is particularly true in a long CA_Loss
period that repairs the initial massive losses when a policer kicks
in.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/tcp.h | 1 +
net/ipv4/tcp_input.c | 25 ++++++++++++++++++++++++-
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 6433cc8..38590fb 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -267,6 +267,7 @@ struct tcp_sock {
* receiver in Recovery. */
u32 prr_out; /* Total number of pkts sent during Recovery. */
u32 delivered; /* Total data packets delivered incl. rexmits */
+ u32 lost; /* Total data packets lost incl. rexmits */
u32 rcv_wnd; /* Current receiver window */
u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ac5b38f..024b579 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -899,12 +899,29 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb)
tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
}
+/* Sum the number of packets on the wire we have marked as lost.
+ * There are two cases we care about here:
+ * a) Packet hasn't been marked lost (nor retransmitted),
+ * and this is the first loss.
+ * b) Packet has been marked both lost and retransmitted,
+ * and this means we think it was lost again.
+ */
+static void tcp_sum_lost(struct tcp_sock *tp, struct sk_buff *skb)
+{
+ __u8 sacked = TCP_SKB_CB(skb)->sacked;
+
+ if (!(sacked & TCPCB_LOST) ||
+ ((sacked & TCPCB_LOST) && (sacked & TCPCB_SACKED_RETRANS)))
+ tp->lost += tcp_skb_pcount(skb);
+}
+
static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb)
{
if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
tcp_verify_retransmit_hint(tp, skb);
tp->lost_out += tcp_skb_pcount(skb);
+ tcp_sum_lost(tp, skb);
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
}
}
@@ -913,6 +930,7 @@ void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb)
{
tcp_verify_retransmit_hint(tp, skb);
+ tcp_sum_lost(tp, skb);
if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) {
tp->lost_out += tcp_skb_pcount(skb);
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
@@ -1890,6 +1908,7 @@ void tcp_enter_loss(struct sock *sk)
struct sk_buff *skb;
bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery;
bool is_reneg; /* is receiver reneging on SACKs? */
+ bool mark_lost;
/* Reduce ssthresh if it has not yet been made inside this window. */
if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
@@ -1923,8 +1942,12 @@ void tcp_enter_loss(struct sock *sk)
if (skb == tcp_send_head(sk))
break;
+ mark_lost = (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) ||
+ is_reneg);
+ if (mark_lost)
+ tcp_sum_lost(tp, skb);
TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED;
- if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || is_reneg) {
+ if (mark_lost) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
tp->lost_out += tcp_skb_pcount(skb);
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 05/16] tcp: switch back to proper tcp_skb_cb size check in tcp_init()
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Eric Dumazet, Soheil Hassas Yeganeh, Neal Cardwell,
Yuchung Cheng
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Eric Dumazet <edumazet@google.com>
Revert to the tcp_skb_cb size check that tcp_init() had before commit
b4772ef879a8 ("net: use common macro for assering skb->cb[] available
size in protocol families"). As related commit 744d5a3e9fe2 ("net:
move skb->dropcount to skb->cb[]") explains, the
sock_skb_cb_check_size() mechanism was added to ensure that there is
space for dropcount, "for protocol families using it". But TCP is not
a protocol using dropcount, so tcp_init() doesn't need to provision
space for dropcount in the skb->cb[], and thus we can revert to the
older form of the tcp_skb_cb size check. Doing so allows TCP to use 4
more bytes of the skb->cb[] space.
Fixes: b4772ef879a8 ("net: use common macro for assering skb->cb[] available size in protocol families")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
---
net/ipv4/tcp.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 5b0b49c..9d1ae18 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3244,11 +3244,12 @@ static void __init tcp_init_mem(void)
void __init tcp_init(void)
{
- unsigned long limit;
int max_rshare, max_wshare, cnt;
+ unsigned long limit;
unsigned int i;
- sock_skb_cb_check_size(sizeof(struct tcp_skb_cb));
+ BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >
+ FIELD_SIZEOF(struct sk_buff, cb));
percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 04/16] net_sched: sch_fq: add low_rate_threshold parameter
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Eric Dumazet, Van Jacobson, Neal Cardwell, Yuchung Cheng,
Nandita Dukkipati, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Eric Dumazet <edumazet@google.com>
This commit adds to the fq module a low_rate_threshold parameter to
insert a delay after all packets if the socket requests a pacing rate
below the threshold.
This helps achieve more precise control of the sending rate with
low-rate paths, especially policers. The basic issue is that if a
congestion control module detects a policer at a certain rate, it may
want fq to be able to shape to that policed rate. That way the sender
can avoid policer drops by having the packets arrive at the policer at
or just under the policed rate.
The default threshold of 550Kbps was chosen analytically so that for
policers or links at 500Kbps or 512Kbps fq would very likely invoke
this mechanism, even if the pacing rate was briefly slightly above the
available bandwidth. This value was then empirically validated with
two years of production testing on YouTube video servers.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/uapi/linux/pkt_sched.h | 2 ++
net/sched/sch_fq.c | 22 +++++++++++++++++++---
2 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index 2382eed..f8e39db 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -792,6 +792,8 @@ enum {
TCA_FQ_ORPHAN_MASK, /* mask applied to orphaned skb hashes */
+ TCA_FQ_LOW_RATE_THRESHOLD, /* per packet delay under this rate */
+
__TCA_FQ_MAX
};
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index e5458b9..40ad4fc 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -94,6 +94,7 @@ struct fq_sched_data {
u32 flow_max_rate; /* optional max rate per flow */
u32 flow_plimit; /* max packets per flow */
u32 orphan_mask; /* mask for orphaned skb */
+ u32 low_rate_threshold;
struct rb_root *fq_root;
u8 rate_enable;
u8 fq_trees_log;
@@ -433,7 +434,7 @@ static struct sk_buff *fq_dequeue(struct Qdisc *sch)
struct fq_flow_head *head;
struct sk_buff *skb;
struct fq_flow *f;
- u32 rate;
+ u32 rate, plen;
skb = fq_dequeue_head(sch, &q->internal);
if (skb)
@@ -482,7 +483,7 @@ begin:
prefetch(&skb->end);
f->credit -= qdisc_pkt_len(skb);
- if (f->credit > 0 || !q->rate_enable)
+ if (!q->rate_enable)
goto out;
/* Do not pace locally generated ack packets */
@@ -493,8 +494,15 @@ begin:
if (skb->sk)
rate = min(skb->sk->sk_pacing_rate, rate);
+ if (rate <= q->low_rate_threshold) {
+ f->credit = 0;
+ plen = qdisc_pkt_len(skb);
+ } else {
+ plen = max(qdisc_pkt_len(skb), q->quantum);
+ if (f->credit > 0)
+ goto out;
+ }
if (rate != ~0U) {
- u32 plen = max(qdisc_pkt_len(skb), q->quantum);
u64 len = (u64)plen * NSEC_PER_SEC;
if (likely(rate))
@@ -662,6 +670,7 @@ static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = {
[TCA_FQ_FLOW_MAX_RATE] = { .type = NLA_U32 },
[TCA_FQ_BUCKETS_LOG] = { .type = NLA_U32 },
[TCA_FQ_FLOW_REFILL_DELAY] = { .type = NLA_U32 },
+ [TCA_FQ_LOW_RATE_THRESHOLD] = { .type = NLA_U32 },
};
static int fq_change(struct Qdisc *sch, struct nlattr *opt)
@@ -716,6 +725,10 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
if (tb[TCA_FQ_FLOW_MAX_RATE])
q->flow_max_rate = nla_get_u32(tb[TCA_FQ_FLOW_MAX_RATE]);
+ if (tb[TCA_FQ_LOW_RATE_THRESHOLD])
+ q->low_rate_threshold =
+ nla_get_u32(tb[TCA_FQ_LOW_RATE_THRESHOLD]);
+
if (tb[TCA_FQ_RATE_ENABLE]) {
u32 enable = nla_get_u32(tb[TCA_FQ_RATE_ENABLE]);
@@ -781,6 +794,7 @@ static int fq_init(struct Qdisc *sch, struct nlattr *opt)
q->fq_root = NULL;
q->fq_trees_log = ilog2(1024);
q->orphan_mask = 1024 - 1;
+ q->low_rate_threshold = 550000 / 8;
qdisc_watchdog_init(&q->watchdog, sch);
if (opt)
@@ -811,6 +825,8 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_put_u32(skb, TCA_FQ_FLOW_REFILL_DELAY,
jiffies_to_usecs(q->flow_refill_delay)) ||
nla_put_u32(skb, TCA_FQ_ORPHAN_MASK, q->orphan_mask) ||
+ nla_put_u32(skb, TCA_FQ_LOW_RATE_THRESHOLD,
+ q->low_rate_threshold) ||
nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log))
goto nla_put_failure;
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 03/16] tcp: use windowed min filter library for TCP min_rtt estimation
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
Refactor the TCP min_rtt code to reuse the new win_minmax library in
lib/win_minmax.c to simplify the TCP code.
This is a pure refactor: the functionality is exactly the same. We
just moved the windowed min code to make TCP easier to read and
maintain, and to allow other parts of the kernel to use the windowed
min/max filter code.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/tcp.h | 5 ++--
include/net/tcp.h | 2 +-
net/ipv4/tcp.c | 2 +-
net/ipv4/tcp_input.c | 64 ++++--------------------------------------------
net/ipv4/tcp_minisocks.c | 2 +-
5 files changed, 10 insertions(+), 65 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c723a46..6433cc8 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -19,6 +19,7 @@
#include <linux/skbuff.h>
+#include <linux/win_minmax.h>
#include <net/sock.h>
#include <net/inet_connection_sock.h>
#include <net/inet_timewait_sock.h>
@@ -234,9 +235,7 @@ struct tcp_sock {
u32 mdev_max_us; /* maximal mdev for the last rtt period */
u32 rttvar_us; /* smoothed mdev_max */
u32 rtt_seq; /* sequence number to update rttvar */
- struct rtt_meas {
- u32 rtt, ts; /* RTT in usec and sampling time in jiffies. */
- } rtt_min[3];
+ struct minmax rtt_min;
u32 packets_out; /* Packets which are "in flight" */
u32 retrans_out; /* Retransmitted packets out */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index fdfbedd..2f1648a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -671,7 +671,7 @@ static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
/* Minimum RTT in usec. ~0 means not available. */
static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
{
- return tp->rtt_min[0].rtt;
+ return minmax_get(&tp->rtt_min);
}
/* Compute the actual receive window we are currently advertising.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index a13fcb3..5b0b49c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -387,7 +387,7 @@ void tcp_init_sock(struct sock *sk)
icsk->icsk_rto = TCP_TIMEOUT_INIT;
tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
- tp->rtt_min[0].rtt = ~0U;
+ minmax_reset(&tp->rtt_min, tcp_time_stamp, ~0U);
/* So many TCP implementations out there (incorrectly) count the
* initial SYN frame in their delayed-ACK and congestion control
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 70b892d..ac5b38f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2879,67 +2879,13 @@ static void tcp_fastretrans_alert(struct sock *sk, const int acked,
*rexmit = REXMIT_LOST;
}
-/* Kathleen Nichols' algorithm for tracking the minimum value of
- * a data stream over some fixed time interval. (E.g., the minimum
- * RTT over the past five minutes.) It uses constant space and constant
- * time per update yet almost always delivers the same minimum as an
- * implementation that has to keep all the data in the window.
- *
- * The algorithm keeps track of the best, 2nd best & 3rd best min
- * values, maintaining an invariant that the measurement time of the
- * n'th best >= n-1'th best. It also makes sure that the three values
- * are widely separated in the time window since that bounds the worse
- * case error when that data is monotonically increasing over the window.
- *
- * Upon getting a new min, we can forget everything earlier because it
- * has no value - the new min is <= everything else in the window by
- * definition and it's the most recent. So we restart fresh on every new min
- * and overwrites 2nd & 3rd choices. The same property holds for 2nd & 3rd
- * best.
- */
static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us)
{
- const u32 now = tcp_time_stamp, wlen = sysctl_tcp_min_rtt_wlen * HZ;
- struct rtt_meas *m = tcp_sk(sk)->rtt_min;
- struct rtt_meas rttm = {
- .rtt = likely(rtt_us) ? rtt_us : jiffies_to_usecs(1),
- .ts = now,
- };
- u32 elapsed;
-
- /* Check if the new measurement updates the 1st, 2nd, or 3rd choices */
- if (unlikely(rttm.rtt <= m[0].rtt))
- m[0] = m[1] = m[2] = rttm;
- else if (rttm.rtt <= m[1].rtt)
- m[1] = m[2] = rttm;
- else if (rttm.rtt <= m[2].rtt)
- m[2] = rttm;
-
- elapsed = now - m[0].ts;
- if (unlikely(elapsed > wlen)) {
- /* Passed entire window without a new min so make 2nd choice
- * the new min & 3rd choice the new 2nd. So forth and so on.
- */
- m[0] = m[1];
- m[1] = m[2];
- m[2] = rttm;
- if (now - m[0].ts > wlen) {
- m[0] = m[1];
- m[1] = rttm;
- if (now - m[0].ts > wlen)
- m[0] = rttm;
- }
- } else if (m[1].ts == m[0].ts && elapsed > wlen / 4) {
- /* Passed a quarter of the window without a new min so
- * take 2nd choice from the 2nd quarter of the window.
- */
- m[2] = m[1] = rttm;
- } else if (m[2].ts == m[1].ts && elapsed > wlen / 2) {
- /* Passed half the window without a new min so take the 3rd
- * choice from the last half of the window.
- */
- m[2] = rttm;
- }
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 wlen = sysctl_tcp_min_rtt_wlen * HZ;
+
+ minmax_running_min(&tp->rtt_min, wlen, tcp_time_stamp,
+ rtt_us ? : jiffies_to_usecs(1));
}
static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f63c73d..5689471 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -464,7 +464,7 @@ struct sock *tcp_create_openreq_child(const struct sock *sk,
newtp->srtt_us = 0;
newtp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
- newtp->rtt_min[0].rtt = ~0U;
+ minmax_reset(&newtp->rtt_min, tcp_time_stamp, ~0U);
newicsk->icsk_rto = TCP_TIMEOUT_INIT;
newtp->packets_out = 0;
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 02/16] lib/win_minmax: windowed min or max estimator
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Neal Cardwell, Van Jacobson, Yuchung Cheng,
Nandita Dukkipati, Eric Dumazet, Soheil Hassas Yeganeh
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
This commit introduces a generic library to estimate either the min or
max value of a time-varying variable over a recent time window. This
is code originally from Kathleen Nichols. The current form of the code
is from Van Jacobson.
A single struct minmax_sample will track the estimated windowed-max
value of the series if you call minmax_running_max() or the estimated
windowed-min value of the series if you call minmax_running_min().
Nearly equivalent code is already in place for minimum RTT estimation
in the TCP stack. This commit extracts that code and generalizes it to
handle both min and max. Moving the code here reduces the footprint
and complexity of the TCP code base and makes the filter generally
available for other parts of the codebase, including an upcoming TCP
congestion control module.
This library works well for time series where the measurements are
smoothly increasing or decreasing.
Signed-off-by: Van Jacobson <vanj@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
---
include/linux/win_minmax.h | 37 +++++++++++++++++
lib/Makefile | 2 +-
lib/win_minmax.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 136 insertions(+), 1 deletion(-)
create mode 100644 include/linux/win_minmax.h
create mode 100644 lib/win_minmax.c
diff --git a/include/linux/win_minmax.h b/include/linux/win_minmax.h
new file mode 100644
index 0000000..5656960
--- /dev/null
+++ b/include/linux/win_minmax.h
@@ -0,0 +1,37 @@
+/**
+ * lib/minmax.c: windowed min/max tracker by Kathleen Nichols.
+ *
+ */
+#ifndef MINMAX_H
+#define MINMAX_H
+
+#include <linux/types.h>
+
+/* A single data point for our parameterized min-max tracker */
+struct minmax_sample {
+ u32 t; /* time measurement was taken */
+ u32 v; /* value measured */
+};
+
+/* State for the parameterized min-max tracker */
+struct minmax {
+ struct minmax_sample s[3];
+};
+
+static inline u32 minmax_get(const struct minmax *m)
+{
+ return m->s[0].v;
+}
+
+static inline u32 minmax_reset(struct minmax *m, u32 t, u32 meas)
+{
+ struct minmax_sample val = { .t = t, .v = meas };
+
+ m->s[2] = m->s[1] = m->s[0] = val;
+ return m->s[0].v;
+}
+
+u32 minmax_running_max(struct minmax *m, u32 win, u32 t, u32 meas);
+u32 minmax_running_min(struct minmax *m, u32 win, u32 t, u32 meas);
+
+#endif
diff --git a/lib/Makefile b/lib/Makefile
index 5dc77a8..df747e5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -22,7 +22,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
sha1.o chacha20.o md5.o irq_regs.o argv_split.o \
flex_proportions.o ratelimit.o show_mem.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
- earlycpio.o seq_buf.o nmi_backtrace.o nodemask.o
+ earlycpio.o seq_buf.o nmi_backtrace.o nodemask.o win_minmax.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/win_minmax.c b/lib/win_minmax.c
new file mode 100644
index 0000000..c8420d4
--- /dev/null
+++ b/lib/win_minmax.c
@@ -0,0 +1,98 @@
+/**
+ * lib/minmax.c: windowed min/max tracker
+ *
+ * Kathleen Nichols' algorithm for tracking the minimum (or maximum)
+ * value of a data stream over some fixed time interval. (E.g.,
+ * the minimum RTT over the past five minutes.) It uses constant
+ * space and constant time per update yet almost always delivers
+ * the same minimum as an implementation that has to keep all the
+ * data in the window.
+ *
+ * The algorithm keeps track of the best, 2nd best & 3rd best min
+ * values, maintaining an invariant that the measurement time of
+ * the n'th best >= n-1'th best. It also makes sure that the three
+ * values are widely separated in the time window since that bounds
+ * the worse case error when that data is monotonically increasing
+ * over the window.
+ *
+ * Upon getting a new min, we can forget everything earlier because
+ * it has no value - the new min is <= everything else in the window
+ * by definition and it's the most recent. So we restart fresh on
+ * every new min and overwrites 2nd & 3rd choices. The same property
+ * holds for 2nd & 3rd best.
+ */
+#include <linux/module.h>
+#include <linux/win_minmax.h>
+
+/* As time advances, update the 1st, 2nd, and 3rd choices. */
+static u32 minmax_subwin_update(struct minmax *m, u32 win,
+ const struct minmax_sample *val)
+{
+ u32 dt = val->t - m->s[0].t;
+
+ if (unlikely(dt > win)) {
+ /*
+ * Passed entire window without a new val so make 2nd
+ * choice the new val & 3rd choice the new 2nd choice.
+ * we may have to iterate this since our 2nd choice
+ * may also be outside the window (we checked on entry
+ * that the third choice was in the window).
+ */
+ m->s[0] = m->s[1];
+ m->s[1] = m->s[2];
+ m->s[2] = *val;
+ if (unlikely(val->t - m->s[0].t > win)) {
+ m->s[0] = m->s[1];
+ m->s[1] = m->s[2];
+ m->s[2] = *val;
+ }
+ } else if (unlikely(m->s[1].t == m->s[0].t) && dt > win/4) {
+ /*
+ * We've passed a quarter of the window without a new val
+ * so take a 2nd choice from the 2nd quarter of the window.
+ */
+ m->s[2] = m->s[1] = *val;
+ } else if (unlikely(m->s[2].t == m->s[1].t) && dt > win/2) {
+ /*
+ * We've passed half the window without finding a new val
+ * so take a 3rd choice from the last half of the window
+ */
+ m->s[2] = *val;
+ }
+ return m->s[0].v;
+}
+
+/* Check if new measurement updates the 1st, 2nd or 3rd choice max. */
+u32 minmax_running_max(struct minmax *m, u32 win, u32 t, u32 meas)
+{
+ struct minmax_sample val = { .t = t, .v = meas };
+
+ if (unlikely(val.v >= m->s[0].v) || /* found new max? */
+ unlikely(val.t - m->s[2].t > win)) /* nothing left in window? */
+ return minmax_reset(m, t, meas); /* forget earlier samples */
+
+ if (unlikely(val.v >= m->s[1].v))
+ m->s[2] = m->s[1] = val;
+ else if (unlikely(val.v >= m->s[2].v))
+ m->s[2] = val;
+
+ return minmax_subwin_update(m, win, &val);
+}
+EXPORT_SYMBOL(minmax_running_max);
+
+/* Check if new measurement updates the 1st, 2nd or 3rd choice min. */
+u32 minmax_running_min(struct minmax *m, u32 win, u32 t, u32 meas)
+{
+ struct minmax_sample val = { .t = t, .v = meas };
+
+ if (unlikely(val.v <= m->s[0].v) || /* found new min? */
+ unlikely(val.t - m->s[2].t > win)) /* nothing left in window? */
+ return minmax_reset(m, t, meas); /* forget earlier samples */
+
+ if (unlikely(val.v <= m->s[1].v))
+ m->s[2] = m->s[1] = val;
+ else if (unlikely(val.v <= m->s[2].v))
+ m->s[2] = val;
+
+ return minmax_subwin_update(m, win, &val);
+}
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 01/16] tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller
Cc: netdev, Soheil Hassas Yeganeh, Neal Cardwell, Yuchung Cheng,
Eric Dumazet, Kenneth Klette Jonassen
In-Reply-To: <1474342763-16715-1-git-send-email-ncardwell@google.com>
From: Soheil Hassas Yeganeh <soheil@google.com>
The upcoming change "lib/win_minmax: windowed min or max estimator"
introduces a struct called minmax, which is then included in
include/linux/tcp.h in the upcoming change "tcp: use windowed min
filter library for TCP min_rtt estimation". This would create a
compilation error for tcp_cdg.c, which defines its own minmax
struct. To avoid this naming conflict (and potentially others in the
future), this commit renames the version used in tcp_cdg.c to
cdg_minmax.
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Kenneth Klette Jonassen <kennetkl@ifi.uio.no>
---
net/ipv4/tcp_cdg.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/tcp_cdg.c b/net/ipv4/tcp_cdg.c
index 03725b2..35b2803 100644
--- a/net/ipv4/tcp_cdg.c
+++ b/net/ipv4/tcp_cdg.c
@@ -56,7 +56,7 @@ MODULE_PARM_DESC(use_shadow, "use shadow window heuristic");
module_param(use_tolerance, bool, 0644);
MODULE_PARM_DESC(use_tolerance, "use loss tolerance heuristic");
-struct minmax {
+struct cdg_minmax {
union {
struct {
s32 min;
@@ -74,10 +74,10 @@ enum cdg_state {
};
struct cdg {
- struct minmax rtt;
- struct minmax rtt_prev;
- struct minmax *gradients;
- struct minmax gsum;
+ struct cdg_minmax rtt;
+ struct cdg_minmax rtt_prev;
+ struct cdg_minmax *gradients;
+ struct cdg_minmax gsum;
bool gfilled;
u8 tail;
u8 state;
@@ -353,7 +353,7 @@ static void tcp_cdg_cwnd_event(struct sock *sk, const enum tcp_ca_event ev)
{
struct cdg *ca = inet_csk_ca(sk);
struct tcp_sock *tp = tcp_sk(sk);
- struct minmax *gradients;
+ struct cdg_minmax *gradients;
switch (ev) {
case CA_EVENT_CWND_RESTART:
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related
* [PATCH v4 net-next 00/16] tcp: BBR congestion control algorithm
From: Neal Cardwell @ 2016-09-20 3:39 UTC (permalink / raw)
To: David Miller; +Cc: netdev, Neal Cardwell
tcp: BBR congestion control algorithm
This patch series implements a new TCP congestion control algorithm:
BBR (Bottleneck Bandwidth and RTT). A paper with a detailed
description of BBR will be published in ACM Queue, September-October
2016, as "BBR: Congestion-Based Congestion Control". BBR is widely
deployed in production at Google.
The patch series starts with a set of supporting infrastructure
changes, including a few that extend the congestion control
framework. The last patch adds BBR as a TCP congestion control
module. Please see individual patches for the details.
- v3 -> v4:
- Updated tcp_bbr.c in "tcp_bbr: add BBR congestion control"
to use const to qualify all the constant parameters.
Thanks to Stephen Hemminger.
- In "tcp_bbr: add BBR congestion control", remove the bbr_rate_kbps()
function, which had a 64-bit divide that would be problematic on some
architectures, and just use bbr_rate_bytes_per_sec() directly.
Thanks to Kenneth Klette Jonassen for suggesting this.
- In "tcp: switch back to proper tcp_skb_cb size check in tcp_init()",
switched from sizeof(skb->cb) to FIELD_SIZEOF.
Thanks to Lance Richardson for suggesting this.
- Updated "tcp_bbr: add BBR congestion control" commit message with
performance data, more details about deployment at Google, and
another reminder to use fq with BBR.
- Updated tcp_bbr.c in "tcp_bbr: add BBR congestion control"
to use MODULE_LICENSE("Dual BSD/GPL").
- v2 -> v3: fix another issue caught by build bots:
- adjust rate_sample struct initialization syntax to allow gcc-4.4 to compile
the "tcp: track data delivery rate for a TCP connection" patch; also
adjusted some similar syntax in "tcp_bbr: add BBR congestion control"
- v1 -> v2: fix issues caught by build bots:
- fix "tcp: export data delivery rate" to use rate64 instead of rate,
so there is a 64-bit numerator for the do_div call
- fix conflicting definitions for minmax caused by
"tcp: use windowed min filter library for TCP min_rtt estimation"
with a new commit:
tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict
- fix warning about the use of __packed in
"tcp: track data delivery rate for a TCP connection",
which involves the addition of a new commit:
tcp: switch back to proper tcp_skb_cb size check in tcp_init()
Eric Dumazet (2):
net_sched: sch_fq: add low_rate_threshold parameter
tcp: switch back to proper tcp_skb_cb size check in tcp_init()
Neal Cardwell (8):
lib/win_minmax: windowed min or max estimator
tcp: use windowed min filter library for TCP min_rtt estimation
tcp: count packets marked lost for a TCP connection
tcp: allow congestion control module to request TSO skb segment count
tcp: export tcp_tso_autosize() and parameterize minimum number of TSO
segments
tcp: export tcp_mss_to_mtu() for congestion control modules
tcp: increase ICSK_CA_PRIV_SIZE from 64 bytes to 88
tcp_bbr: add BBR congestion control
Soheil Hassas Yeganeh (2):
tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict
tcp: track application-limited rate samples
Yuchung Cheng (4):
tcp: track data delivery rate for a TCP connection
tcp: export data delivery rate
tcp: allow congestion control to expand send buffer differently
tcp: new CC hook to set sending rate with rate_sample in any CA state
include/linux/tcp.h | 14 +-
include/linux/win_minmax.h | 37 ++
include/net/inet_connection_sock.h | 4 +-
include/net/tcp.h | 53 ++-
include/uapi/linux/inet_diag.h | 13 +
include/uapi/linux/pkt_sched.h | 2 +
include/uapi/linux/tcp.h | 3 +
lib/Makefile | 2 +-
lib/win_minmax.c | 98 ++++
net/ipv4/Kconfig | 18 +
net/ipv4/Makefile | 3 +-
net/ipv4/tcp.c | 26 +-
net/ipv4/tcp_bbr.c | 896 +++++++++++++++++++++++++++++++++++++
net/ipv4/tcp_cdg.c | 12 +-
net/ipv4/tcp_cong.c | 2 +-
net/ipv4/tcp_input.c | 154 +++----
net/ipv4/tcp_minisocks.c | 5 +-
net/ipv4/tcp_output.c | 27 +-
net/ipv4/tcp_rate.c | 186 ++++++++
net/sched/sch_fq.c | 22 +-
20 files changed, 1470 insertions(+), 107 deletions(-)
create mode 100644 include/linux/win_minmax.h
create mode 100644 lib/win_minmax.c
create mode 100644 net/ipv4/tcp_bbr.c
create mode 100644 net/ipv4/tcp_rate.c
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply
* [PATCH net-next] net: ethernet: mediatek: enhance with avoiding superfluous assignment inside mtk_get_ethtool_stats
From: sean.wang @ 2016-09-20 3:26 UTC (permalink / raw)
To: john, davem; +Cc: nbd, netdev, linux-mediatek, keyhaede, objelf, Sean Wang
From: Sean Wang <sean.wang@mediatek.com>
data_src is unchanged inside the loop, so this patch moves
the assignment to outside the loop to avoid unnecessarily
assignment
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
---
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 481f360..ca6b501 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -2137,8 +2137,9 @@ static void mtk_get_ethtool_stats(struct net_device *dev,
}
}
+ data_src = (u64 *)hwstats;
+
do {
- data_src = (u64 *)hwstats;
data_dst = data;
start = u64_stats_fetch_begin_irq(&hwstats->syncp);
--
1.9.1
^ permalink raw reply related
* 23221 netdev
From: ddccc @ 2016-09-20 2:48 UTC (permalink / raw)
To: netdev
[-- Attachment #1: INFO_3929613035991_netdev.zip --]
[-- Type: application/zip, Size: 4612 bytes --]
^ permalink raw reply
* Re: [PATCHv2 net-next 0/2] Preparation for mv88e6390
From: Vivien Didelot @ 2016-09-20 2:18 UTC (permalink / raw)
To: Andrew Lunn, David Miller; +Cc: netdev, Andrew Lunn
In-Reply-To: <1474331590-7959-1-git-send-email-andrew@lunn.ch>
Hi Andrew,
Andrew Lunn <andrew@lunn.ch> writes:
> These two patches are a couple of preparation steps for supporting the
> the MV88E6390 family of chips. This is a new generation from Marvell,
> and will need more feature flags than are currently available in an
> unsigned long. Expand to an unsigned long long. The MV88E6390 also
> places its port registers somewhere else, so add a wrapper around port
> register access.
>
> v2: Rework wrappers to use mv88e6xxx_{read|write}
> Simpliy some (err < ) to (err)
> Add Reviewed by tag.
>
> Andrew Lunn (2):
> net: dsa: mv88e6xxx: Convert flag bits to unsigned long long
> WIP: net: dsa: mv88e6xxx: Implement interrupt support.
Since there's a need for a v3, note that the above summary is wrong.
Thanks,
Vivien
^ permalink raw reply
* Re: [PATCHv2 net-next 1/2] net: dsa: mv88e6xxx: Add helper for accessing port registers
From: Vivien Didelot @ 2016-09-20 2:17 UTC (permalink / raw)
To: Andrew Lunn, David Miller; +Cc: netdev, Andrew Lunn
In-Reply-To: <1474331590-7959-2-git-send-email-andrew@lunn.ch>
Hi Andrew,
Andrew Lunn <andrew@lunn.ch> writes:
<snip>
> @@ -585,19 +601,19 @@ static void mv88e6xxx_adjust_link(struct dsa_switch *ds, int port,
> struct phy_device *phydev)
> {
> struct mv88e6xxx_chip *chip = ds->priv;
> - u32 reg;
> - int ret;
> + u16 reg;
> + int err;
>
> if (!phy_is_pseudo_fixed_link(phydev))
> return;
>
> mutex_lock(&chip->reg_lock);
>
> - ret = _mv88e6xxx_reg_read(chip, REG_PORT(port), PORT_PCS_CTRL);
> - if (ret < 0)
> + err = mv88e6xxx_port_read(chip, port, PORT_PCS_CTRL, ®);
> + if (err)
> goto out;
>
> - reg = ret & ~(PORT_PCS_CTRL_LINK_UP |
> + reg = reg & ~(PORT_PCS_CTRL_LINK_UP |
reg &= ~(PORT_PCS_CTRL_LINK_UP |
> PORT_PCS_CTRL_FORCE_LINK |
> PORT_PCS_CTRL_DUPLEX_FULL |
> PORT_PCS_CTRL_FORCE_DUPLEX |
<snip>
> /* Wait up to one second for reset to complete. */
> timeout = jiffies + 1 * HZ;
> while (time_before(jiffies, timeout)) {
> - ret = _mv88e6xxx_reg_read(chip, REG_GLOBAL, 0x00);
> - if (ret < 0)
> - return ret;
> + err = _mv88e6xxx_reg_read(chip, REG_GLOBAL, 0x00);
> + if (err)
> + return err;
Ouch! Wrong s/ret/err/ here.
>
> - if ((ret & is_reset) == is_reset)
> + if ((err & is_reset) == is_reset)
Here as well. Keep ret or use mv88e6xxx_read().
> break;
> usleep_range(1000, 2000);
> }
> if (time_after(jiffies, timeout))
> - ret = -ETIMEDOUT;
> + err = -ETIMEDOUT;
> else
> - ret = 0;
> + err = 0;
>
> - return ret;
> + return err;
> }
>
> static int mv88e6xxx_serdes_power_on(struct mv88e6xxx_chip *chip)
Thanks,
Vivien
^ permalink raw reply
* Re: [PATCH net 0/3] mlx5 fixes to 4.8-rc6
From: David Miller @ 2016-09-20 2:10 UTC (permalink / raw)
To: ogerlitz; +Cc: netdev, tariqt, hadarh, amirva
In-Reply-To: <1474212029-1052-1-git-send-email-ogerlitz@mellanox.com>
From: Or Gerlitz <ogerlitz@mellanox.com>
Date: Sun, 18 Sep 2016 18:20:26 +0300
> This series series has a fix from Roi to memory corruption bug in
> the bulk flow counters code and two late and hopefully last fixes
> from me to the new eswitch offloads code.
>
> Series done over net commit 37dd348 "bna: fix crash in bnad_get_strings()"
Series applied, thanks.
^ permalink raw reply
* Re: [PATCHv6 net-next 00/15] BPF hardware offload (cls_bpf for now)
From: David Miller @ 2016-09-20 2:08 UTC (permalink / raw)
To: jakub.kicinski; +Cc: netdev, ast, daniel
In-Reply-To: <1474211365-20088-1-git-send-email-jakub.kicinski@netronome.com>
From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Sun, 18 Sep 2016 16:09:10 +0100
> As spotted by Daniel JIT might have accessed indexes past the end
> of verifier's reg_state array.
This series doesn't apply cleanly to net-next, please respin.
Thanks.
^ permalink raw reply
* Re: [PATCH net-next 1/1] net sched: stylistic cleanups
From: David Miller @ 2016-09-20 2:04 UTC (permalink / raw)
To: jhs; +Cc: netdev
In-Reply-To: <1474202733-14740-1-git-send-email-jhs@emojatatu.com>
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Sun, 18 Sep 2016 08:45:33 -0400
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Applied.
^ permalink raw reply
* Re: [PATCH net-next 1/1] net sched actions police: peg drop stats for conforming traffic
From: David Miller @ 2016-09-20 2:04 UTC (permalink / raw)
To: jhs; +Cc: netdev, mrv
In-Reply-To: <1474199588-11032-1-git-send-email-jhs@emojatatu.com>
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Sun, 18 Sep 2016 07:53:08 -0400
> From: Roman Mashak <mrv@mojatatu.com>
>
> setting conforming action to drop is a valid policy.
> When it is set we need to at least see the stats indicating it
> for debugging.
>
> Signed-off-by: Roman Mashak <mrv@mojatatu.com>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Applied.
^ permalink raw reply
* Re: [PATCH v3 net-next 2/2] net sched ife action: Introduce skb tcindex metadata encap decap
From: David Miller @ 2016-09-20 1:57 UTC (permalink / raw)
To: jhs; +Cc: netdev, xiyou.wangcong
In-Reply-To: <1474198303-10645-2-git-send-email-jhs@emojatatu.com>
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Sun, 18 Sep 2016 07:31:43 -0400
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> Sample use case of how this is encoded:
> user space via tuntap (or a connected VM/Machine/container)
> encodes the tcindex TLV.
>
> Sample use case of decoding:
> IFE action decodes it and the skb->tc_index is then used to classify.
> So something like this for encoded ICMP packets:
>
> .. first decode then reclassify... skb->tcindex will be set
> sudo $TC filter add dev $ETH parent ffff: prio 2 protocol 0xbeef \
> u32 match u32 0 0 flowid 1:1 \
> action ife decode reclassify
>
> ...next match the decode icmp packet...
> sudo $TC filter add dev $ETH parent ffff: prio 4 protocol ip \
> u32 match ip protocol 1 0xff flowid 1:1 \
> action continue
>
> ... last classify it using the tcindex classifier and do someaction..
> sudo $TC filter add dev $ETH parent ffff: prio 5 protocol ip \
> handle 0x11 tcindex classid 1:1 \
> action blah..
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Applied.
^ permalink raw reply
* Re: [PATCH v3 net-next 1/2] net sched ife action: add 16 bit helpers
From: David Miller @ 2016-09-20 1:57 UTC (permalink / raw)
To: jhs; +Cc: netdev, xiyou.wangcong
In-Reply-To: <1474198303-10645-1-git-send-email-jhs@emojatatu.com>
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Sun, 18 Sep 2016 07:31:42 -0400
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> encoder and checker for 16 bits metadata
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Applied.
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox