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From: Martin KaFai Lau <kafai@fb.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Qitao Xu <qitao.xu@bytedance.com>,
	Cong Wang <cong.wang@bytedance.com>, bpf <bpf@vger.kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [Patch net-next 02/13] ipv4: introduce tracepoint trace_ip_queue_xmit()
Date: Wed, 11 Aug 2021 16:08:27 -0700	[thread overview]
Message-ID: <20210811230827.24x5ovwqk6thqsan@kafai-mbp> (raw)
In-Reply-To: <CAM_iQpUorOGfdthXe+wkAhFOv8i2zFhBgF0NUBQEBMkGYTavuw@mail.gmail.com>

On Wed, Aug 11, 2021 at 03:48:36PM -0700, Cong Wang wrote:
> On Wed, Aug 11, 2021 at 2:23 PM Martin KaFai Lau <kafai@fb.com> wrote:
> > Instead of adding tracepoints, the bpf fexit prog can be used here and
> > the bpf prog will have the sk, skb, and ret available (example in fexit_test.c).
> > Some tracepoints in this set can also be done with bpf fentry/fexit.
> > Does bpf fentry/fexit work for your use case?
> 
> Well, kprobe works too in this perspective. The problem with kprobe
> or fexit is that there is no guarantee the function still exists in kernel
> during iteration. Kernel is free to delete or rename it. With tracepoint,
> even if ip_queue_xmit() were renamed, the same tracepoint must
> remain in the kernel.
Some of the function names are hardly changed.  Considering it is
not always cost free based on another thread, this is not a strong
enough reason to add so many tracepoints while other options
are available.

  reply	other threads:[~2021-08-11 23:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 18:57 [Patch net-next 00/13] net: add more tracepoints to TCP/IP stack Cong Wang
2021-08-05 18:57 ` [Patch net-next 01/13] net: introduce a new header file include/trace/events/ip.h Cong Wang
2021-08-05 18:57 ` [Patch net-next 02/13] ipv4: introduce tracepoint trace_ip_queue_xmit() Cong Wang
2021-08-06 10:08   ` Eric Dumazet
2021-08-09 20:32     ` Cong Wang
2021-08-11 21:22   ` Martin KaFai Lau
2021-08-11 22:48     ` Cong Wang
2021-08-11 23:08       ` Martin KaFai Lau [this message]
2021-08-12  0:37         ` Cong Wang
2021-08-12  5:46           ` Martin KaFai Lau
2021-08-05 18:57 ` [Patch net-next 03/13] tcp: introduce tracepoint trace_tcp_transmit_skb() Cong Wang
2021-08-05 18:57 ` [Patch net-next 04/13] udp: introduce tracepoint trace_udp_send_skb() Cong Wang
2021-08-05 18:57 ` [Patch net-next 05/13] udp: introduce tracepoint trace_udp_v6_send_skb() Cong Wang
2021-08-05 18:57 ` [Patch net-next 06/13] ipv4: introduce tracepoint trace_ip_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 07/13] ipv6: introduce tracepoint trace_ipv6_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 08/13] ipv4: introduce tracepoint trace_ip_local_deliver_finish() Cong Wang
2021-08-05 18:57 ` [Patch net-next 09/13] udp: introduce tracepoint trace_udp_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 10/13] ipv6: introduce tracepoint trace_udpv6_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 11/13] tcp: introduce tracepoint trace_tcp_v4_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 12/13] ipv6: introduce tracepoint trace_tcp_v6_rcv() Cong Wang
2021-08-05 18:57 ` [Patch net-next 13/13] sock: introduce tracepoint trace_sk_data_ready() Cong Wang
2021-08-06  2:22 ` [Patch net-next 00/13] net: add more tracepoints to TCP/IP stack Cong Wang

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