tcp_rcv_space_adjust is called every time data is copied to user space,
introducing a tcp tracepoint for which could show us when the packet is
copied to user.
This could help us figure out whether there's latency in user process.
When a tcp packet arrives, tcp_rcv_established() will be called and with
the existed tracepoint tcp_probe we could get the time when this packet
arrives.
Then this packet will be copied to user, and tcp_rcv_space_adjust will
be called and with this new introduced tracepoint we could get the time
when this packet is copied to user.
arrives time : user process time => latency caused by user
tcp_probe tcp_rcv_space_adjust
Hence in the printk message, sk_cookie is printed as a key to relate
tcp_rcv_space_adjust with tcp_probe.
Maybe we could export sockfd in this new tracepoint as well, then we
could relate this new tracepoint with epoll/read/recv* tracepoints, and
finally that could show us the whole lifespan of this packet. But we
could also implement that with pid as these functions are executed in
process context.
Signed-off-by: Yafang Shao <[email protected]>
---
v1 -> v2: use sk_cookie as key suggested by Eric.
---
include/trace/events/tcp.h | 33 +++++++++++++++++++++++++++------
net/ipv4/tcp_input.c | 2 ++
2 files changed, 29 insertions(+), 6 deletions(-)
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 3dd6802..814f754 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -10,6 +10,7 @@
#include <linux/tracepoint.h>
#include <net/ipv6.h>
#include <net/tcp.h>
+#include <linux/sock_diag.h>
#define TP_STORE_V4MAPPED(__entry, saddr, daddr) \
do { \
@@ -125,6 +126,7 @@
__array(__u8, daddr, 4)
__array(__u8, saddr_v6, 16)
__array(__u8, daddr_v6, 16)
+ __field(__u64, sock_cookie)
),
TP_fast_assign(
@@ -144,12 +146,24 @@
TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
+
+ /*
+ * sk_cookie is used to identify a socket, with which we could
+ * relate this tracepoint with other tracepoints,
+ * i.e. tcp_probe.
+ * If we needn't this relation, then sk_cookie is useless;
+ * if we need this relation, then tcp_probe is already set,
+ * and sk_cookie is already set in tcp_probe, so we could get
+ * the value directly.
+ */
+ __entry->sock_cookie = atomic64_read(&sk->sk_cookie);
),
- TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c",
+ TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c sock_cookie=%llu",
__entry->sport, __entry->dport,
__entry->saddr, __entry->daddr,
- __entry->saddr_v6, __entry->daddr_v6)
+ __entry->saddr_v6, __entry->daddr_v6,
+ __entry->sock_cookie)
);
DEFINE_EVENT(tcp_event_sk, tcp_receive_reset,
@@ -166,6 +180,13 @@
TP_ARGS(sk)
);
+DEFINE_EVENT(tcp_event_sk, tcp_rcv_space_adjust,
+
+ TP_PROTO(const struct sock *sk),
+
+ TP_ARGS(sk)
+);
+
TRACE_EVENT(tcp_retransmit_synack,
TP_PROTO(const struct sock *sk, const struct request_sock *req),
@@ -232,6 +253,7 @@
__field(__u32, snd_wnd)
__field(__u32, srtt)
__field(__u32, rcv_wnd)
+ __field(__u64, sock_cookie)
),
TP_fast_assign(
@@ -256,15 +278,14 @@
__entry->rcv_wnd = tp->rcv_wnd;
__entry->ssthresh = tcp_current_ssthresh(sk);
__entry->srtt = tp->srtt_us >> 3;
+ __entry->sock_cookie = sock_gen_cookie(sk);
),
- TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x "
- "snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u "
- "rcv_wnd=%u",
+ TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llu",
__entry->saddr, __entry->daddr, __entry->mark,
__entry->length, __entry->snd_nxt, __entry->snd_una,
__entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
- __entry->srtt, __entry->rcv_wnd)
+ __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie)
);
#endif /* _TRACE_TCP_H */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index f93687f..43ad468 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -582,6 +582,8 @@ void tcp_rcv_space_adjust(struct sock *sk)
u32 copied;
int time;
+ trace_tcp_rcv_space_adjust(sk);
+
tcp_mstamp_refresh(tp);
time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
if (time < (tp->rcv_rtt_est.rtt_us >> 3) || tp->rcv_rtt_est.rtt_us == 0)
--
1.8.3.1
On 04/17/2018 09:36 AM, Yafang Shao wrote:
> tcp_rcv_space_adjust is called every time data is copied to user space,
> introducing a tcp tracepoint for which could show us when the packet is
> copied to user.
> This could help us figure out whether there's latency in user process.
>
> When a tcp packet arrives, tcp_rcv_established() will be called and with
> the existed tracepoint tcp_probe we could get the time when this packet
> arrives.
> Then this packet will be copied to user, and tcp_rcv_space_adjust will
> be called and with this new introduced tracepoint we could get the time
> when this packet is copied to user.
>
> arrives time : user process time => latency caused by user
> tcp_probe tcp_rcv_space_adjust
Sorry, I could not parse these :/
>
> Hence in the printk message, sk_cookie is printed as a key to relate
> tcp_rcv_space_adjust with tcp_probe.
>
> Maybe we could export sockfd in this new tracepoint as well, then we
> could relate this new tracepoint with epoll/read/recv* tracepoints, and
> finally that could show us the whole lifespan of this packet. But we
> could also implement that with pid as these functions are executed in
> process context.
>
> Signed-off-by: Yafang Shao <[email protected]>
>
> ---
> v1 -> v2: use sk_cookie as key suggested by Eric.
> ---
> include/trace/events/tcp.h | 33 +++++++++++++++++++++++++++------
> net/ipv4/tcp_input.c | 2 ++
> 2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
> index 3dd6802..814f754 100644
> --- a/include/trace/events/tcp.h
> +++ b/include/trace/events/tcp.h
> @@ -10,6 +10,7 @@
> #include <linux/tracepoint.h>
> #include <net/ipv6.h>
> #include <net/tcp.h>
> +#include <linux/sock_diag.h>
>
> #define TP_STORE_V4MAPPED(__entry, saddr, daddr) \
> do { \
> @@ -125,6 +126,7 @@
> __array(__u8, daddr, 4)
> __array(__u8, saddr_v6, 16)
> __array(__u8, daddr_v6, 16)
> + __field(__u64, sock_cookie)
> ),
>
> TP_fast_assign(
> @@ -144,12 +146,24 @@
>
> TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
> sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
> +
> + /*
> + * sk_cookie is used to identify a socket, with which we could
> + * relate this tracepoint with other tracepoints,
> + * i.e. tcp_probe.
> + * If we needn't this relation, then sk_cookie is useless;
> + * if we need this relation, then tcp_probe is already set,
> + * and sk_cookie is already set in tcp_probe, so we could get
> + * the value directly.
> + */
> + __entry->sock_cookie = atomic64_read(&sk->sk_cookie);
Please scrap this comment and simply use the real thing.
_entry->sock_cookie = sock_gen_cookie(sk);
We build generic events.
Being able to filter many TCP events on one socket cookie will be useful
If you worry about sock_gen_cookie(sk) being too expensive, then we can add an inline helper
for the fast path (when sk_cookie has been already set)
> ),
>
> - TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c",
> + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c sock_cookie=%llu",
iproute2/ss command uses hexadcimal output for socket cookie. Please use %llx for consistency.
> On Apr 17, 2018, at 9:36 AM, Yafang Shao <[email protected]> wrote:
>
> tcp_rcv_space_adjust is called every time data is copied to user space,
> introducing a tcp tracepoint for which could show us when the packet is
> copied to user.
> This could help us figure out whether there's latency in user process.
>
> When a tcp packet arrives, tcp_rcv_established() will be called and with
> the existed tracepoint tcp_probe we could get the time when this packet
> arrives.
> Then this packet will be copied to user, and tcp_rcv_space_adjust will
> be called and with this new introduced tracepoint we could get the time
> when this packet is copied to user.
>
> arrives time : user process time => latency caused by user
> tcp_probe tcp_rcv_space_adjust
>
> Hence in the printk message, sk_cookie is printed as a key to relate
> tcp_rcv_space_adjust with tcp_probe.
>
> Maybe we could export sockfd in this new tracepoint as well, then we
> could relate this new tracepoint with epoll/read/recv* tracepoints, and
> finally that could show us the whole lifespan of this packet. But we
> could also implement that with pid as these functions are executed in
> process context.
>
> Signed-off-by: Yafang Shao <[email protected]>
>
> ---
> v1 -> v2: use sk_cookie as key suggested by Eric.
> ---
> include/trace/events/tcp.h | 33 +++++++++++++++++++++++++++------
> net/ipv4/tcp_input.c | 2 ++
> 2 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
> index 3dd6802..814f754 100644
> --- a/include/trace/events/tcp.h
> +++ b/include/trace/events/tcp.h
> @@ -10,6 +10,7 @@
> #include <linux/tracepoint.h>
> #include <net/ipv6.h>
> #include <net/tcp.h>
> +#include <linux/sock_diag.h>
>
> #define TP_STORE_V4MAPPED(__entry, saddr, daddr) \
> do { \
> @@ -125,6 +126,7 @@
> __array(__u8, daddr, 4)
> __array(__u8, saddr_v6, 16)
> __array(__u8, daddr_v6, 16)
> + __field(__u64, sock_cookie)
> ),
>
> TP_fast_assign(
> @@ -144,12 +146,24 @@
>
> TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
> sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
> +
> + /*
> + * sk_cookie is used to identify a socket, with which we could
> + * relate this tracepoint with other tracepoints,
> + * i.e. tcp_probe.
> + * If we needn't this relation, then sk_cookie is useless;
> + * if we need this relation, then tcp_probe is already set,
> + * and sk_cookie is already set in tcp_probe, so we could get
> + * the value directly.
> + */
> + __entry->sock_cookie = atomic64_read(&sk->sk_cookie);
> ),
>
> - TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c",
> + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c sock_cookie=%llu",
> __entry->sport, __entry->dport,
> __entry->saddr, __entry->daddr,
> - __entry->saddr_v6, __entry->daddr_v6)
> + __entry->saddr_v6, __entry->daddr_v6,
> + __entry->sock_cookie)
> );
>
> DEFINE_EVENT(tcp_event_sk, tcp_receive_reset,
> @@ -166,6 +180,13 @@
> TP_ARGS(sk)
> );
>
> +DEFINE_EVENT(tcp_event_sk, tcp_rcv_space_adjust,
> +
> + TP_PROTO(const struct sock *sk),
> +
> + TP_ARGS(sk)
> +);
> +
> TRACE_EVENT(tcp_retransmit_synack,
>
> TP_PROTO(const struct sock *sk, const struct request_sock *req),
> @@ -232,6 +253,7 @@
> __field(__u32, snd_wnd)
> __field(__u32, srtt)
> __field(__u32, rcv_wnd)
> + __field(__u64, sock_cookie)
> ),
>
> TP_fast_assign(
> @@ -256,15 +278,14 @@
> __entry->rcv_wnd = tp->rcv_wnd;
> __entry->ssthresh = tcp_current_ssthresh(sk);
> __entry->srtt = tp->srtt_us >> 3;
> + __entry->sock_cookie = sock_gen_cookie(sk);
> ),
>
> - TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x "
> - "snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u "
> - "rcv_wnd=%u",
> + TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llu",
> __entry->saddr, __entry->daddr, __entry->mark,
> __entry->length, __entry->snd_nxt, __entry->snd_una,
> __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
> - __entry->srtt, __entry->rcv_wnd)
> + __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie)
> );
>
> #endif /* _TRACE_TCP_H */
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index f93687f..43ad468 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -582,6 +582,8 @@ void tcp_rcv_space_adjust(struct sock *sk)
> u32 copied;
> int time;
>
> + trace_tcp_rcv_space_adjust(sk);
> +
> tcp_mstamp_refresh(tp);
> time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
> if (time < (tp->rcv_rtt_est.rtt_us >> 3) || tp->rcv_rtt_est.rtt_us == 0)
> --
> 1.8.3.1
>
If I understand this correctly, you can get all the information you need with
a kprobe on tcp_rcv_space_adjust(). Why is it necessary to introduce a new
tracepoint?
Thanks,
Song
On Wed, Apr 18, 2018 at 1:27 AM, Eric Dumazet <[email protected]> wrote:
>
>
> On 04/17/2018 09:36 AM, Yafang Shao wrote:
>> tcp_rcv_space_adjust is called every time data is copied to user space,
>> introducing a tcp tracepoint for which could show us when the packet is
>> copied to user.
>> This could help us figure out whether there's latency in user process.
>>
>> When a tcp packet arrives, tcp_rcv_established() will be called and with
>> the existed tracepoint tcp_probe we could get the time when this packet
>> arrives.
>> Then this packet will be copied to user, and tcp_rcv_space_adjust will
>> be called and with this new introduced tracepoint we could get the time
>> when this packet is copied to user.
>>
>> arrives time : user process time => latency caused by user
>> tcp_probe tcp_rcv_space_adjust
>
> Sorry, I could not parse these :/
>
Sorry for the poor expression. Will improve it.
I mean with these two tracepoint we could calculate the latency that
if the user process can't process this packet immdiately.
>>
>> Hence in the printk message, sk_cookie is printed as a key to relate
>> tcp_rcv_space_adjust with tcp_probe.
>>
>> Maybe we could export sockfd in this new tracepoint as well, then we
>> could relate this new tracepoint with epoll/read/recv* tracepoints, and
>> finally that could show us the whole lifespan of this packet. But we
>> could also implement that with pid as these functions are executed in
>> process context.
>>
>> Signed-off-by: Yafang Shao <[email protected]>
>>
>> ---
>> v1 -> v2: use sk_cookie as key suggested by Eric.
>> ---
>> include/trace/events/tcp.h | 33 +++++++++++++++++++++++++++------
>> net/ipv4/tcp_input.c | 2 ++
>> 2 files changed, 29 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
>> index 3dd6802..814f754 100644
>> --- a/include/trace/events/tcp.h
>> +++ b/include/trace/events/tcp.h
>> @@ -10,6 +10,7 @@
>> #include <linux/tracepoint.h>
>> #include <net/ipv6.h>
>> #include <net/tcp.h>
>> +#include <linux/sock_diag.h>
>>
>> #define TP_STORE_V4MAPPED(__entry, saddr, daddr) \
>> do { \
>> @@ -125,6 +126,7 @@
>> __array(__u8, daddr, 4)
>> __array(__u8, saddr_v6, 16)
>> __array(__u8, daddr_v6, 16)
>> + __field(__u64, sock_cookie)
>> ),
>>
>> TP_fast_assign(
>> @@ -144,12 +146,24 @@
>>
>> TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
>> sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
>> +
>> + /*
>> + * sk_cookie is used to identify a socket, with which we could
>> + * relate this tracepoint with other tracepoints,
>> + * i.e. tcp_probe.
>> + * If we needn't this relation, then sk_cookie is useless;
>> + * if we need this relation, then tcp_probe is already set,
>> + * and sk_cookie is already set in tcp_probe, so we could get
>> + * the value directly.
>> + */
>> + __entry->sock_cookie = atomic64_read(&sk->sk_cookie);
>
> Please scrap this comment and simply use the real thing.
>
> _entry->sock_cookie = sock_gen_cookie(sk);
>
> We build generic events.
>
> Being able to filter many TCP events on one socket cookie will be useful
>
> If you worry about sock_gen_cookie(sk) being too expensive, then we can add an inline helper
> for the fast path (when sk_cookie has been already set)
>
Will improve.
>> ),
>>
>> - TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c",
>> + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c sock_cookie=%llu",
>
>
> iproute2/ss command uses hexadcimal output for socket cookie. Please use %llx for consistency.
>
OK
On Wed, Apr 18, 2018 at 1:38 AM, Song Liu <[email protected]> wrote:
>
>
>> On Apr 17, 2018, at 9:36 AM, Yafang Shao <[email protected]> wrote:
>>
>> tcp_rcv_space_adjust is called every time data is copied to user space,
>> introducing a tcp tracepoint for which could show us when the packet is
>> copied to user.
>> This could help us figure out whether there's latency in user process.
>>
>> When a tcp packet arrives, tcp_rcv_established() will be called and with
>> the existed tracepoint tcp_probe we could get the time when this packet
>> arrives.
>> Then this packet will be copied to user, and tcp_rcv_space_adjust will
>> be called and with this new introduced tracepoint we could get the time
>> when this packet is copied to user.
>>
>> arrives time : user process time => latency caused by user
>> tcp_probe tcp_rcv_space_adjust
>>
>> Hence in the printk message, sk_cookie is printed as a key to relate
>> tcp_rcv_space_adjust with tcp_probe.
>>
>> Maybe we could export sockfd in this new tracepoint as well, then we
>> could relate this new tracepoint with epoll/read/recv* tracepoints, and
>> finally that could show us the whole lifespan of this packet. But we
>> could also implement that with pid as these functions are executed in
>> process context.
>>
>> Signed-off-by: Yafang Shao <[email protected]>
>>
>> ---
>> v1 -> v2: use sk_cookie as key suggested by Eric.
>> ---
>> include/trace/events/tcp.h | 33 +++++++++++++++++++++++++++------
>> net/ipv4/tcp_input.c | 2 ++
>> 2 files changed, 29 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
>> index 3dd6802..814f754 100644
>> --- a/include/trace/events/tcp.h
>> +++ b/include/trace/events/tcp.h
>> @@ -10,6 +10,7 @@
>> #include <linux/tracepoint.h>
>> #include <net/ipv6.h>
>> #include <net/tcp.h>
>> +#include <linux/sock_diag.h>
>>
>> #define TP_STORE_V4MAPPED(__entry, saddr, daddr) \
>> do { \
>> @@ -125,6 +126,7 @@
>> __array(__u8, daddr, 4)
>> __array(__u8, saddr_v6, 16)
>> __array(__u8, daddr_v6, 16)
>> + __field(__u64, sock_cookie)
>> ),
>>
>> TP_fast_assign(
>> @@ -144,12 +146,24 @@
>>
>> TP_STORE_ADDRS(__entry, inet->inet_saddr, inet->inet_daddr,
>> sk->sk_v6_rcv_saddr, sk->sk_v6_daddr);
>> +
>> + /*
>> + * sk_cookie is used to identify a socket, with which we could
>> + * relate this tracepoint with other tracepoints,
>> + * i.e. tcp_probe.
>> + * If we needn't this relation, then sk_cookie is useless;
>> + * if we need this relation, then tcp_probe is already set,
>> + * and sk_cookie is already set in tcp_probe, so we could get
>> + * the value directly.
>> + */
>> + __entry->sock_cookie = atomic64_read(&sk->sk_cookie);
>> ),
>>
>> - TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c",
>> + TP_printk("sport=%hu dport=%hu saddr=%pI4 daddr=%pI4 saddrv6=%pI6c daddrv6=%pI6c sock_cookie=%llu",
>> __entry->sport, __entry->dport,
>> __entry->saddr, __entry->daddr,
>> - __entry->saddr_v6, __entry->daddr_v6)
>> + __entry->saddr_v6, __entry->daddr_v6,
>> + __entry->sock_cookie)
>> );
>>
>> DEFINE_EVENT(tcp_event_sk, tcp_receive_reset,
>> @@ -166,6 +180,13 @@
>> TP_ARGS(sk)
>> );
>>
>> +DEFINE_EVENT(tcp_event_sk, tcp_rcv_space_adjust,
>> +
>> + TP_PROTO(const struct sock *sk),
>> +
>> + TP_ARGS(sk)
>> +);
>> +
>> TRACE_EVENT(tcp_retransmit_synack,
>>
>> TP_PROTO(const struct sock *sk, const struct request_sock *req),
>> @@ -232,6 +253,7 @@
>> __field(__u32, snd_wnd)
>> __field(__u32, srtt)
>> __field(__u32, rcv_wnd)
>> + __field(__u64, sock_cookie)
>> ),
>>
>> TP_fast_assign(
>> @@ -256,15 +278,14 @@
>> __entry->rcv_wnd = tp->rcv_wnd;
>> __entry->ssthresh = tcp_current_ssthresh(sk);
>> __entry->srtt = tp->srtt_us >> 3;
>> + __entry->sock_cookie = sock_gen_cookie(sk);
>> ),
>>
>> - TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x "
>> - "snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u "
>> - "rcv_wnd=%u",
>> + TP_printk("src=%pISpc dest=%pISpc mark=%#x length=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llu",
>> __entry->saddr, __entry->daddr, __entry->mark,
>> __entry->length, __entry->snd_nxt, __entry->snd_una,
>> __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
>> - __entry->srtt, __entry->rcv_wnd)
>> + __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie)
>> );
>>
>> #endif /* _TRACE_TCP_H */
>> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
>> index f93687f..43ad468 100644
>> --- a/net/ipv4/tcp_input.c
>> +++ b/net/ipv4/tcp_input.c
>> @@ -582,6 +582,8 @@ void tcp_rcv_space_adjust(struct sock *sk)
>> u32 copied;
>> int time;
>>
>> + trace_tcp_rcv_space_adjust(sk);
>> +
>> tcp_mstamp_refresh(tp);
>> time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
>> if (time < (tp->rcv_rtt_est.rtt_us >> 3) || tp->rcv_rtt_est.rtt_us == 0)
>> --
>> 1.8.3.1
>>
>
> If I understand this correctly, you can get all the information you need with
> a kprobe on tcp_rcv_space_adjust(). Why is it necessary to introduce a new
> tracepoint?
>
Tracepoint is less expensive and more cnovinient, that is the same
reason why tcp_probe.c was removed and tcp_probe tracepoint was
introduced.
Thanks
Yafang