From: Joe Perches <joe@perches.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>,
jbaron@akamai.com, mingo@redhat.com,
Nicolas Boichat <drinkcat@chromium.org>,
kernel@axis.com, corbet@lwn.net, pmladek@suse.com,
sergey.senozhatsky@gmail.com, john.ogness@linutronix.de,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] dynamic debug: allow printing to trace event
Date: Wed, 26 Aug 2020 12:53:57 -0700 [thread overview]
Message-ID: <9bfb4c4bd1415a8ce527a913730672508a8e8330.camel@perches.com> (raw)
In-Reply-To: <20200826153203.1a65c35d@oasis.local.home>
On Wed, 2020-08-26 at 15:32 -0400, Steven Rostedt wrote:
> On Tue, 25 Aug 2020 08:53:25 -0700
> Joe Perches <joe@perches.com> wrote:
>
> > > The print buffer is statically allocated and managed using code borrowed
> > > from __ftrace_trace_stack() and is limited to 256 bytes (four of these
> > > are allocated per CPU to handle the various contexts); anything larger
> > > will be truncated.
> >
> > There is an effort to avoid using trace_printk and the like
> > so perhaps this feature should have the same compile time
> > guard.
>
> No, this is fine for being in a production kernel. Basically, these are
> simply debug printk()s that can also be put into the trace buffer. The
> key difference to trace_printk() is that they are an event that needs
> to be enabled to write into the buffer.
It just seems like a backdoor way to convert various pr_debug functions
(dev_dbg/netdev_dbg, et al) into tracing.
What's the real value? Timing data? Something else?
next prev parent reply other threads:[~2020-08-26 19:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 15:33 [PATCH v3 0/2] Dynamic debug trace support Vincent Whitchurch
2020-08-25 15:33 ` [PATCH v3 1/2] dynamic debug: split enable and printk flags Vincent Whitchurch
2020-08-25 15:33 ` [PATCH v3 2/2] dynamic debug: allow printing to trace event Vincent Whitchurch
2020-08-25 15:53 ` Joe Perches
2020-08-26 19:32 ` Steven Rostedt
2020-08-26 19:53 ` Joe Perches [this message]
2020-09-02 12:17 ` Vincent Whitchurch
2023-12-26 16:57 ` Guilherme G. Piccoli
2023-12-27 8:29 ` Vincent Whitchurch
2023-12-27 13:06 ` Guilherme G. Piccoli
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