linux-kernel - Re: [PATCH] tracepoint: Allow livepatch module add trace event

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Date:   Tue, 15 Nov 2022 10:38:34 +0800
From:   Jianlin Lv <iecedge@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     alison.schofield@...el.com, davidgow@...gle.com,
        thunder.leizhen@...wei.com, jianlv@...y.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracepoint: Allow livepatch module add trace event

On Tue, Nov 15, 2022 at 1:22 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> On Wed,  2 Nov 2022 16:02:36 +0000
> Jianlin Lv <iecedge@...il.com> wrote:
>
> > In the case of keeping the system running, the preferred method for
> > tracing the kernel is dynamic tracing (kprobe), but the drawback of
> > this method is that events are lost, especially when tracing packages
> > in the network stack.
>
> I'm not against this change, but the above is where I'm a bit confused. How
> are events more likely to be lost with kprobes over a static event?

We have encountered a case of kprobes missing event, detailed
information can refer to the following link:
https://github.com/iovisor/bcc/issues/4198

Replacing kprobe with ’bpf + raw tracepoint‘,  no missing events occur.

> -- Steve