From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <mhiramat@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Andy Lutomirski <luto@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users
Date: Thu, 22 Nov 2018 14:42:38 +0100 [thread overview]
Message-ID: <20181122134238.GU2131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181122074605.063a7525@vmware.local.home>
On Thu, Nov 22, 2018 at 07:46:05AM -0500, Steven Rostedt wrote:
> On Thu, 22 Nov 2018 11:08:12 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > On Wed, Nov 21, 2018 at 08:27:08PM -0500, Steven Rostedt wrote:
> > > Well the fuction graph tracer is arguably the strongest of the tracers.
> > > It shows both the entrance and exit of a function, can give the timings
> > > of a function, and shows the execution of the code quite nicely.
> > >
> > > But it has one major flaw.
> > >
> > > It can't let more than one user access it at a time.
> >
> > The reason I 'never' use it is performance, it _sucks_.. I've never ran
> > into the multi-user issue.
>
> And performance is also something to fix (it has improved lately, you
> probably haven't noticed).
Indeed, I've not recently used it.
> > So while I don't think the rewrite is bad, this argument here is.
>
> Except that we plan on merging kretprobe with function graph tracing.
> This also solves the issue that Mark Rutland has with ret protection.
> He has a solution for function graph tracing, but not with kretprobes.
Sure. But you didn't make that argument.
> And yes, there's also the case of being able to trace to different
> buffers where you can have a full function graph tracing enabled and
> also trace a subset that you want to have.
>
> Just because you don't need it, doesn't mean it's not needed by others.
Not saying that; just saying the argument doesn't hold. It is not the
_one_ flaw.
next prev parent reply other threads:[~2018-11-22 13:42 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-22 1:27 [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 01/14] fgraph: Create a fgraph.c file to store function graph infrastructure Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 02/14] fgraph: Have set_graph_notrace only affect function_graph tracer Steven Rostedt
2018-11-23 0:01 ` Namhyung Kim
2018-11-23 17:37 ` Steven Rostedt
2018-11-24 5:49 ` Namhyung Kim
2018-11-24 18:41 ` Steven Rostedt
2018-11-26 4:54 ` Namhyung Kim
2018-11-22 1:27 ` [RFC][PATCH 03/14] arm64: function_graph: Remove use of FTRACE_NOTRACE_DEPTH Steven Rostedt
2018-11-27 19:31 ` Will Deacon
2018-11-27 19:50 ` Steven Rostedt
2018-12-05 21:50 ` [PATCH 03/14 v2] " Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 04/14] function_graph: Remove the " Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 05/14] ftrace: Create new ftrace-internal.h header Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 06/14] fgraph: Move function graph specific code into fgraph.c Steven Rostedt
2018-11-23 6:11 ` Joel Fernandes
2018-11-23 17:58 ` Steven Rostedt
2018-11-23 18:11 ` Steven Rostedt
2018-11-23 22:13 ` Joel Fernandes
2018-11-26 7:25 ` Masami Hiramatsu
2018-11-22 1:27 ` [RFC][PATCH 07/14] fgraph: Add new fgraph_ops structure to enable function graph hooks Steven Rostedt
2018-11-23 2:59 ` Joel Fernandes
2018-11-23 18:25 ` Steven Rostedt
2018-11-26 11:30 ` Masami Hiramatsu
2018-11-26 21:06 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 08/14] function_graph: Remove unused task_curr_ret_stack() Steven Rostedt
2018-11-26 7:40 ` Masami Hiramatsu
2018-11-26 21:26 ` Steven Rostedt
2018-11-26 10:02 ` Joey Pabalinas
2018-11-26 21:27 ` Steven Rostedt
2018-11-26 21:37 ` Joey Pabalinas
2018-11-22 1:27 ` [RFC][PATCH 09/14] function_graph: Move ftrace_graph_get_addr() to fgraph.c Steven Rostedt
2018-11-23 3:13 ` Joel Fernandes
2018-11-23 19:25 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 10/14] function_graph: Have profiler use new helper ftrace_graph_get_ret_stack() Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 11/14] function_graph: Convert ret_stack to a series of longs Steven Rostedt
2018-11-24 5:31 ` Joel Fernandes
2018-11-26 16:07 ` Masami Hiramatsu
2018-11-26 16:26 ` Steven Rostedt
2018-11-28 1:38 ` Joel Fernandes
2018-11-26 21:31 ` Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 12/14] function_graph: Add an array structure that will allow multiple callbacks Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 13/14] function_graph: Allow multiple users to attach to function graph Steven Rostedt
2018-11-22 1:27 ` [RFC][PATCH 14/14] function_graph: Allow for more than one callback to be registered Steven Rostedt
2018-11-22 10:08 ` [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users Peter Zijlstra
2018-11-22 12:46 ` Steven Rostedt
2018-11-22 13:42 ` Peter Zijlstra [this message]
2018-11-26 9:21 ` Masami Hiramatsu
2018-11-26 16:32 ` Steven Rostedt
2018-11-29 14:29 ` Masami Hiramatsu
2018-11-29 16:46 ` Steven Rostedt
2018-11-30 2:26 ` Masami Hiramatsu
2018-11-30 3:24 ` Steven Rostedt
2018-11-30 14:11 ` Masami Hiramatsu
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