Ping... On 2015/1/9 12:06, Wang Nan wrote: > Hi Steven Rostedt, > > During studying your code we find a problem, please see below. > >> >> From: "Steven Rostedt (Red Hat)" <rost...@goodmis.org> >> >> Enabling tracepoints at boot up can be very useful. The tracepoint >> can be initialized right after RCU has been. There's no need to >> wait for the early_initcall() to be called. That's too late for some >> things that can use tracepoints for debugging. Move the logic to >> enable tracepoints out of the initcalls and into init/main.c to >> right after rcu_init(). >> >> This also allows trace_printk() to be used early too. >> >> Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos >> Link: http://lkml.kernel.org/r/20141214164104.307127...@goodmis.org >> >> Reviewed-by: Paul E. McKenney <paul...@linux.vnet.ibm.com> >> Suggested-by: Thomas Gleixner <t...@linutronix.de> >> Tested-by: Thomas Gleixner <t...@linutronix.de> >> Acked-by: Thomas Gleixner <t...@linutronix.de> >> Signed-off-by: Steven Rostedt <rost...@goodmis.org> > > [...] > >> +void __init trace_init(void) >> +{ >> + tracer_alloc_buffers(); >> + init_ftrace_syscalls(); >> + trace_event_init(); >> +} >> + > > [...] > >> + >> +void __init trace_event_init(void) >> +{ >> + event_trace_memsetup(); >> + init_ftrace_syscalls(); >> + event_trace_enable(); >> +} >> + > > init_ftrace_syscalls() get called twice by trace_init() and > trace_event_init(), some resources are wasted. > At lease one of them can be removed. > > In addition, could you please have a look at my early kprobe patch series? > > http://lists.infradead.org/pipermail/linux-arm-kernel/2015-January/313835.html > > Which enables kprobe very early, even before memory initialized. I think it > is possible to combine these > early tracing facilities together. > > Thank you! > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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