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Date: Wed, 20 Aug 2008 09:12:54 -0400 (EDT)
From: Steven Rostedt <rostedt@goodmis.org>
To: Eran Liberty <liberty@extricom.com>
Subject: Re: ftrace introduces instability into kernel 2.6.27(-rc2,-rc3)
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Cc: linuxppc-dev@ozlabs.org, Steven Rostedt <srostedt@redhat.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	linux-kernel@vger.kernel.org
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On Wed, 20 Aug 2008, Eran Liberty wrote:

> Steven Rostedt wrote:
> > On Tue, 19 Aug 2008, Eran Liberty wrote:
> > 
> >   
> > > Steven Rostedt wrote:
> > >     
> > > >         
> > > > > Testing tracer sched_switch: PASSED
> > > > > Testing tracer ftrace: PASSED
> > > > > Testing dynamic ftrace: PASSED
> > > > >         
> > 
> > Do you have PREEMPT_TRACER enabled, or any other tracer for that matter?
> > 
> > -- Steve
> >   
> I can see stack trace & context trace, but they are derived from other choices
> (I can not un select them)

Yeah, those are not bad.

> 
> cat .config | grep TRACE
> CONFIG_STACKTRACE_SUPPORT=y
> CONFIG_HAVE_ARCH_TRACEHOOK=y
> # CONFIG_BLK_DEV_IO_TRACE is not set
> CONFIG_STACKTRACE=y
> # CONFIG_BACKTRACE_SELF_TEST is not set
> CONFIG_HAVE_FTRACE=y
> CONFIG_HAVE_DYNAMIC_FTRACE=y
> CONFIG_FTRACE=y
> # CONFIG_SCHED_TRACER is not set
> CONFIG_CONTEXT_SWITCH_TRACER=y
> CONFIG_DYNAMIC_FTRACE=y
> CONFIG_FTRACE_SELFTEST=y
> CONFIG_FTRACE_STARTUP_TEST=y

You must not have PREEMPT on, so the PREEMPT_TRACER will not show up.

The reason I asked, is that my PowerBook runs fine without PREEMPT_TRACER 
but is very unstable when I have PREEMPT_TRACER enabled.

-- Steve


> >   
> > > > > Oops: Exception in kernel mode, sig: 11 [#1]
> > > > > Exsw1600
> > > > > Modules linked in:
> > > > > NIP: c00bbb20 LR: c00bbb20 CTR: 00000000
> > > > >             
> > 
> > 
> >   
> 
>