[PATCH] powerpc: tracing: Add powerpc tracepoints for interrupt entry and exit

[Steven Rostedt]

On Sun, 2009-10-18 at 22:01 +1100, Anton Blanchard wrote:
> Hi Ben,
> 
> > Breaks 6xx_defconfig:
> 
> Yuck. Since the CREATE_TRACE_POINTS stuff appears to need a non trivial number
> of includes it might be best just to fold it into one of the tracepoint call
> sites like this.
> 
> --
> 
> This patch adds powerpc specific tracepoints for interrupt entry and exit.
> 
> While we already have generic irq_handler_entry and irq_handler_exit
> tracepoints there are cases on our virtualised powerpc machines where an
> interrupt is presented to the OS, but subsequently handled by the hypervisor.
> This means no OS interrupt handler is invoked.
> 
> Here is an example on a POWER6 machine with the patch below applied:
>  
> <idle>-0     [006]  3243.949840744: irq_entry: pt_regs=c0000000ce31fb10
> <idle>-0     [006]  3243.949850520: irq_exit: pt_regs=c0000000ce31fb10
> 
> <idle>-0     [007]  3243.950218208: irq_entry: pt_regs=c0000000ce323b10
> <idle>-0     [007]  3243.950224080: irq_exit: pt_regs=c0000000ce323b10
> 
> <idle>-0     [000]  3244.021879320: irq_entry: pt_regs=c000000000a63aa0
> <idle>-0     [000]  3244.021883616: irq_handler_entry: irq=87 handler=eth0
> <idle>-0     [000]  3244.021887328: irq_handler_exit: irq=87 return=handled
> <idle>-0     [000]  3244.021897408: irq_exit: pt_regs=c000000000a63aa0
> 
> Here we see two phantom interrupts (no handler was invoked), followed
> by a real interrupt for eth0. Without the tracepoints in this patch we
> would have missed the phantom interrupts.
> 
> Since these would be the first arch specific tracepoints, I'd like to make
> sure we agree on naming. The tracepoints live in events/powerpc/*, but I'm
> wondering if the tracepoint name should also contain the arch name, eg
> powerpc_irq_entry/powerpc_irq_exit. Thoughts?
> 
> Signed-off-by: Anton Blanchard <anton at samba.org>
> --

I'm fine with the name "powerpc".

Acked-by: Steven Rostedt <rostedt at goodmis.org>