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Date: Mon, 8 Dec 2008 13:22:21 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] tracing/function-graph-tracer: signal interrupts
	entry/exit points on outpout
Message-ID: <20081208122221.GA16560@elte.hu>
References: <493C7058.4060709@gmail.com>
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> +/* Used during output to find the interrupts entry/exit points */
> +const char *ftrace_graph_irq_entries[] = {
> +	"smp_call_function_single_interrupt",
> +	"xen_call_function_single_interrupt",
> +	"wrapper_smp_local_timer_interrupt",
> +	"smp_irq_move_cleanup_interrupt",
> +	"smp_call_function_interrupt",
> +	"xen_call_function_interrupt",
> +	"smp_apic_timer_interrupt",
> +	"uv_bau_message_interrupt",
> +	"mce_threshold_interrupt",
> +	"smp_spurious_interrupt",
> +	"smp_thermal_interrupt",
> +	"smp_error_interrupt",
> +	"do_IRQ",
> +	NULL

hm, couldnt we move these symbols to a separate section, and then only 
check for [section.start ... section.end] instead of this ugly and slow 
array?

Missing a few annotations initially is no big deal - we wont have 
pretty-print. do_IRQ() and smp_apic_timer_interrupt is what matters most 
in practice. "__irqentry" section annotation or so, which puts them into 
.text.irqentry or so - and then irqentry_start/end are extracted via 
appropriate glue in the arch/x86/kernel/vmlinux* linker script.

	Ingo