From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>,
Vince Weaver <vincent.weaver@maine.edu>,
Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>,
Steven Rostedt <rostedt@goodmis.org>,
Jiri Olsa <jolsa@redhat.com>
Subject: Re: x86_pmu_start WARN_ON.
Date: Thu, 20 Feb 2014 19:23:32 +0100 [thread overview]
Message-ID: <20140220182332.GE22728@two.firstfloor.org> (raw)
In-Reply-To: <20140220181538.GK9987@twins.programming.kicks-ass.net>
On Thu, Feb 20, 2014 at 07:15:38PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 20, 2014 at 09:31:19AM -0800, Andi Kleen wrote:
> > Peter Zijlstra <peterz@infradead.org> writes:
> > >
> > > It will; trace_printk() works without -pg, I think you didn't read the
> > > instructions very well.
> >
> > Ok, you enable and disable it again. I won't guess why you do that.
>
> To grow the trace buffers; it starts with just a few pages per cpu; once
> you switch to an actual tracer it allocates a sensible amount.
>
> You can grow it with another interface; but then I'd have to like
> remember what that was and how big the normal buffers are. Simply
> toggling between tracers is far easier.
I see.
>
> > > And there's a very good reason not to apply your patch; you can route
> > > the function tracer into perf, guess what happens when perf calls the
> > > function tracer again :-)
> >
> > How?
>
> I think by using the /debug/tracing/events/ftrace/function event, but
> I'm not actually sure, I've never used it nor did I write the code to do
> it. Jolsa did all that IIRC.
>
> All I know is that we had some 'fun' bugs around there sometime back.
Ok.
I don't think it would be a problem in any case, the ftrace code has recursion
protection.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2014-02-20 18:23 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 19:02 x86_pmu_start WARN_ON Dave Jones
2014-02-10 21:26 ` Vince Weaver
2014-02-11 13:29 ` Peter Zijlstra
2014-02-12 21:04 ` Vince Weaver
2014-02-13 14:11 ` Vince Weaver
2014-02-13 17:35 ` Vince Weaver
2014-02-13 22:13 ` Vince Weaver
2014-02-17 15:28 ` Peter Zijlstra
2014-02-18 18:30 ` Vince Weaver
2014-02-18 22:20 ` Vince Weaver
2014-02-19 10:19 ` Peter Zijlstra
2014-02-19 22:34 ` Vince Weaver
2014-02-20 10:08 ` Peter Zijlstra
2014-02-20 15:47 ` Andi Kleen
2014-02-20 15:54 ` Peter Zijlstra
2014-02-20 17:31 ` Andi Kleen
2014-02-20 18:15 ` Peter Zijlstra
2014-02-20 18:23 ` Andi Kleen [this message]
2014-02-20 19:04 ` Steven Rostedt
2014-02-20 16:26 ` Steven Rostedt
2014-02-20 17:00 ` Peter Zijlstra
2014-02-20 17:43 ` Steven Rostedt
2014-02-20 17:46 ` Steven Rostedt
2014-02-20 18:18 ` Peter Zijlstra
2014-02-20 18:03 ` Vince Weaver
2014-02-20 18:23 ` Peter Zijlstra
2014-02-20 18:54 ` Vince Weaver
2014-02-20 19:21 ` Vince Weaver
2014-02-20 19:46 ` Vince Weaver
2014-02-21 14:37 ` Vince Weaver
2014-02-21 15:03 ` Peter Zijlstra
2014-02-21 20:18 ` Vince Weaver
2014-02-24 11:28 ` Peter Zijlstra
2014-02-26 5:59 ` Vince Weaver
2014-02-27 13:32 ` [tip:perf/core] perf/x86: Fix event scheduling tip-bot for Peter Zijlstra
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