[ltt-dev] Kernel crashes when creating a trace

[Mathieu Desnoyers]

* Ashwin Tanugula (ashwin.tanugula at broadcom.com) wrote:
>  
> 
> > > Connecting /proc/sys/debug/ltt/markers/vm_state/vm_map
> > > #
> > > #
> > > #
> > > # cd ltt-control-0.75-15112009/lttctl/.libs/
> > > # lttctl -C -w /tmp/trace1 trace1
> > > Linux Trace Toolkit Trace Control 0.75-15112009
>  
> 
> > OK, it makes more sense. Can you try the latest lttng with this patch then ?
> 
> Mathieu,
> 
> Without "return 1;", it still hangs, I will enable lockdep and send you the log ASAP.
> 

Oh ! I found the mistake. Erroneous "cmpxchg" in the 32-bit version of
the trace clock. That should work without the return 1; now. Please try
0.174.

Now if you still have some "Kernel/LTTV event size differs for event.."
that's another problem we'll have to address. It seems to work fine on
x86 32/64 here though. Do you view the trace on the same architecture
you record it on ? What are the arch endiannesses ?

Mathieu


> With "return 1", I still cannot view the trace.
> 
> $ lttv-gui -t trace2
> Xlib:  extension "RANDR" missing on display ":0.0".
> ** Message: statistics viewer : background computation data ready.
> 
> ** ERROR **: Kernel/LTTV event size differs for event (null): kernel 8, LTTV 0
> aborting...
> lttv/lttv/lttv-gui: line 10: 23282 Aborted                 (core dumped) $LTTV_CMD.real -m lttvwindow -m guievents -m guifilter -m guicontrolflow -m resourceview -m guistatistics -m guitracecontrol $*
> 
> 
> $ lttv-gui -t trace3
> Xlib:  extension "RANDR" missing on display ":0.0".
> ** Message: statistics viewer : background computation data ready.
> 
> ** ERROR **: Kernel/LTTV event size differs for event (null): kernel 8, LTTV 0
> aborting...
> 
> lttv/lttv/lttv-gui: line 10: 23303 Aborted                 (core dumped) $LTTV_CMD.real -m lttvwindow -m guievents -m guifilter -m guicontrolflow -m resourceview -m guistatistics -m guitracecontrol $*
> 
> trace clock provide sleep free get put
> 
> 
> Thanks,
> Ashwin
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>
> ---
>  kernel/trace/trace-clock-32-to-64.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> Index: linux-2.6-lttng/kernel/trace/trace-clock-32-to-64.c
> ===================================================================
> --- linux-2.6-lttng.orig/kernel/trace/trace-clock-32-to-64.c	2009-11-17 17:28:21.000000000 -0500
> +++ linux-2.6-lttng/kernel/trace/trace-clock-32-to-64.c	2009-11-17 17:30:33.000000000 -0500
> @@ -232,21 +232,27 @@ static int __cpuinit hotcpu_callback(str
>  	switch (action) {
>  	case CPU_UP_PREPARE:
>  	case CPU_UP_PREPARE_FROZEN:
> +		spin_lock(&synthetic_tsc_lock);
>  		if (synthetic_tsc_refcount)
>  			prepare_synthetic_tsc(hotcpu);
> +		spin_unlock(&synthetic_tsc_lock);
>  		break;
>  	case CPU_ONLINE:
>  	case CPU_ONLINE_FROZEN:
> +		spin_lock(&synthetic_tsc_lock);
>  		if (synthetic_tsc_refcount)
>  			enable_synthetic_tsc(hotcpu);
> +		spin_unlock(&synthetic_tsc_lock);
>  		break;
>  #ifdef CONFIG_HOTPLUG_CPU
>  	case CPU_UP_CANCELED:
>  	case CPU_UP_CANCELED_FROZEN:
>  	case CPU_DEAD:
>  	case CPU_DEAD_FROZEN:
> +		spin_lock(&synthetic_tsc_lock);
>  		if (synthetic_tsc_refcount)
>  			disable_synthetic_tsc(hotcpu);
> +		spin_unlock(&synthetic_tsc_lock);
>  		break;
>  #endif /* CONFIG_HOTPLUG_CPU */
>  	}
> @@ -257,7 +263,6 @@ void get_synthetic_tsc(void)  {
>  	int cpu;
>  
> -	get_online_cpus();
>  	spin_lock(&synthetic_tsc_lock);
>  	if (synthetic_tsc_refcount++)
>  		goto end;
> @@ -269,7 +274,6 @@ void get_synthetic_tsc(void)
>  	}
>  end:
>  	spin_unlock(&synthetic_tsc_lock);
> -	put_online_cpus();
>  }
>  EXPORT_SYMBOL_GPL(get_synthetic_tsc);
>  
> @@ -277,7 +281,6 @@ void put_synthetic_tsc(void)  {
>  	int cpu;
>  
> -	get_online_cpus();
>  	spin_lock(&synthetic_tsc_lock);
>  	WARN_ON(synthetic_tsc_refcount <= 0);
>  	if (synthetic_tsc_refcount != 1 || !synthetic_tsc_enabled) @@ -289,7 +292,6 @@ void put_synthetic_tsc(void)
>  end:
>  	synthetic_tsc_refcount--;
>  	spin_unlock(&synthetic_tsc_lock);
> -	put_online_cpus();
>  }
>  EXPORT_SYMBOL_GPL(put_synthetic_tsc);
>  
> 
> > 
> > Thanks,
> > Ashwin
> > 
> > 
> 
> --
> Mathieu Desnoyers
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> 
> 
> 

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68