Re: [External] Re: [PATCH] tcp/udp: add tracepoint for send recv length

[运辉崔]

Cong Wang <xiyou.wangcong@xxxxxxxxx> 于2023年1月2日周一 03:10写道：
>
> On Thu, Dec 29, 2022 at 04:02:07PM +0800, Yunhui Cui wrote:
> > From: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
> >
> > Add a tracepoint for capturing TCP segments with
> > a send or receive length. This makes it easy to obtain
> > the packet sending and receiving information of each process
> > in the user mode, such as the netatop tool.
>
> You can obtain the same information with kretprobe:
> https://www.gcardone.net/2020-07-31-per-process-bandwidth-monitoring-on-Linux-with-bpftrace/

As we know, kprobe gets the result by trapping in an exception, which
loses performance compared to tracepoint.

We did a test for performance comparison. The results are as follows.

Time per request
sock_sendmsg(k,kr):  12.382ms， tcp_send_length(tracepoint): 11.887ms，
without hook：11.222ms

It can be seen that the performance loss of tracepoint is only half of
that of kprobe.