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SubjectRe: [PATCH v4] sock: add tracepoint for send recv length
On Sun, Jan 08, 2023 at 10:55:45AM +0800, Yunhui Cui wrote:
>Add 2 tracepoints to monitor the tcp/udp traffic
>of per process and per cgroup.
>
>Regarding monitoring the tcp/udp traffic of each process, there are two
>existing solutions, the first one is https://www.atoptool.nl/netatop.php.
>The second is via kprobe/kretprobe.
>
>Netatop solution is implemented by registering the hook function at the
>hook point provided by the netfilter framework.
>
>These hook functions may be in the soft interrupt context and cannot
>directly obtain the pid. Some data structures are added to bind packets
>and processes. For example, struct taskinfobucket, struct taskinfo ...
>
>Every time the process sends and receives packets it needs multiple
>hashmaps,resulting in low performance and it has the problem fo inaccurate
>tcp/udp traffic statistics(for example: multiple threads share sockets).
>
>We can obtain the information with kretprobe, but as we know, kprobe gets
>the result by trappig in an exception, which loses performance compared
>to tracepoint.
>
>We compared the performance of tracepoints with the above two methods, and
>the results are as follows:
>
>ab -n 1000000 -c 1000 -r http://127.0.0.1/index.html

AFAIK, ab are relatively slow compared to some network benchmarks since
it's a http benchmark.
Can you test other benchmarks like sockperf or redis-benchmark with small
packets, and check the PPS drop ? Those benchmarks should have larger PPS.

Like Eric pointed out, those tracepoints in the datapath are not free,
its better to make sure we don't get a noticeable PPS drop after adding
those tracepoints.

Thanks.

>without trace:
>Time per request: 39.660 [ms] (mean)
>Time per request: 0.040 [ms] (mean, across all concurrent requests)
>
>netatop:
>Time per request: 50.717 [ms] (mean)
>Time per request: 0.051 [ms] (mean, across all concurrent requests)
>
>kr:
>Time per request: 43.168 [ms] (mean)
>Time per request: 0.043 [ms] (mean, across all concurrent requests)
>
>tracepoint:
>Time per request: 41.004 [ms] (mean)
>Time per request: 0.041 [ms] (mean, across all concurrent requests
>
>It can be seen that tracepoint has better performance.
>
>Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
>Signed-off-by: Xiongchun Duan <duanxiongchun@bytedance.com>
>---
> include/trace/events/sock.h | 48 +++++++++++++++++++++++++++++++++++++
> net/socket.c | 23 ++++++++++++++----
> 2 files changed, 67 insertions(+), 4 deletions(-)
>
>diff --git a/include/trace/events/sock.h b/include/trace/events/sock.h
>index 777ee6cbe933..d00a5b272404 100644
>--- a/include/trace/events/sock.h
>+++ b/include/trace/events/sock.h
>@@ -263,6 +263,54 @@ TRACE_EVENT(inet_sk_error_report,
> __entry->error)
> );
>
>+/*
>+ * sock send/recv msg length
>+ */
>+DECLARE_EVENT_CLASS(sock_msg_length,
>+
>+ TP_PROTO(struct sock *sk, __u16 family, __u16 protocol, int ret,
>+ int flags),
>+
>+ TP_ARGS(sk, family, protocol, ret, flags),
>+
>+ TP_STRUCT__entry(
>+ __field(void *, sk)
>+ __field(__u16, family)
>+ __field(__u16, protocol)
>+ __field(int, length)
>+ __field(int, error)
>+ __field(int, flags)
>+ ),
>+
>+ TP_fast_assign(
>+ __entry->sk = sk;
>+ __entry->family = sk->sk_family;
>+ __entry->protocol = sk->sk_protocol;
>+ __entry->length = ret > 0 ? ret : 0;
>+ __entry->error = ret < 0 ? ret : 0;
>+ __entry->flags = flags;
>+ ),
>+
>+ TP_printk("sk address = %p, family = %s protocol = %s, length = %d, error = %d, flags = 0x%x",
>+ __entry->sk, show_family_name(__entry->family),
>+ show_inet_protocol_name(__entry->protocol),
>+ __entry->length,
>+ __entry->error, __entry->flags)
>+);
>+
>+DEFINE_EVENT(sock_msg_length, sock_send_length,
>+ TP_PROTO(struct sock *sk, __u16 family, __u16 protocol, int ret,
>+ int flags),
>+
>+ TP_ARGS(sk, family, protocol, ret, flags)
>+);
>+
>+DEFINE_EVENT(sock_msg_length, sock_recv_length,
>+ TP_PROTO(struct sock *sk, __u16 family, __u16 protocol, int ret,
>+ int flags),
>+
>+ TP_ARGS(sk, family, protocol, ret, flags)
>+);
> #endif /* _TRACE_SOCK_H */
>
> /* This part must be outside protection */
>diff --git a/net/socket.c b/net/socket.c
>index 888cd618a968..60a1ff95b4b1 100644
>--- a/net/socket.c
>+++ b/net/socket.c
>@@ -106,6 +106,7 @@
> #include <net/busy_poll.h>
> #include <linux/errqueue.h>
> #include <linux/ptp_clock_kernel.h>
>+#include <trace/events/sock.h>
>
> #ifdef CONFIG_NET_RX_BUSY_POLL
> unsigned int sysctl_net_busy_read __read_mostly;
>@@ -715,6 +716,9 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg)
> inet_sendmsg, sock, msg,
> msg_data_left(msg));
> BUG_ON(ret == -EIOCBQUEUED);
>+
>+ trace_sock_send_length(sock->sk, sock->sk->sk_family,
>+ sock->sk->sk_protocol, ret, 0);
> return ret;
> }
>
>@@ -992,9 +996,15 @@ INDIRECT_CALLABLE_DECLARE(int inet6_recvmsg(struct socket *, struct msghdr *,
> static inline int sock_recvmsg_nosec(struct socket *sock, struct msghdr *msg,
> int flags)
> {
>- return INDIRECT_CALL_INET(sock->ops->recvmsg, inet6_recvmsg,
>- inet_recvmsg, sock, msg, msg_data_left(msg),
>- flags);
>+ int ret = INDIRECT_CALL_INET(sock->ops->recvmsg, inet6_recvmsg,
>+ inet_recvmsg, sock, msg,
>+ msg_data_left(msg), flags);
>+
>+ trace_sock_recv_length(sock->sk, sock->sk->sk_family,
>+ sock->sk->sk_protocol,
>+ !(flags & MSG_PEEK) ? ret :
>+ (ret < 0 ? ret : 0), flags);
>+ return ret;
> }
>
> /**
>@@ -1044,6 +1054,7 @@ static ssize_t sock_sendpage(struct file *file, struct page *page,
> {
> struct socket *sock;
> int flags;
>+ int ret;
>
> sock = file->private_data;
>
>@@ -1051,7 +1062,11 @@ static ssize_t sock_sendpage(struct file *file, struct page *page,
> /* more is a combination of MSG_MORE and MSG_SENDPAGE_NOTLAST */
> flags |= more;
>
>- return kernel_sendpage(sock, page, offset, size, flags);
>+ ret = kernel_sendpage(sock, page, offset, size, flags);
>+
>+ trace_sock_send_length(sock->sk, sock->sk->sk_family,
>+ sock->sk->sk_protocol, ret, 0);
>+ return ret;
> }
>
> static ssize_t sock_splice_read(struct file *file, loff_t *ppos,
>--
>2.20.1

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