All of lore.kernel.org
 help / color / mirror / Atom feed
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.

  reply	other threads:[~2018-11-22 13:42 UTC|newest]

Thread overview: 58+ 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
2018-11-22  1:27   ` Steven Rostedt
2018-11-27 19:31   ` Will Deacon
2018-11-27 19:31     ` Will Deacon
2018-11-27 19:50     ` Steven Rostedt
2018-11-27 19:50       ` Steven Rostedt
2018-12-05 21:50       ` [PATCH 03/14 v2] " Steven Rostedt
2018-12-05 21:50         ` 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20181122134238.GU2131@hirez.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=akpm@linux-foundation.org \
    --cc=frederic@kernel.org \
    --cc=joel@joelfernandes.org \
    --cc=jpoimboe@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mhiramat@kernel.org \
    --cc=mingo@kernel.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.