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Subject: Ftrace: can trace kthread?
From: "Figo.zhang" <zhangtianfei@leadcoretech.com>
To: Li Zefan <lizf@cn.fujitsu.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Steven Rostedt <srostedt@redhat.com>
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Date: Thu, 21 Oct 2010 15:55:32 +0800
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hi,

is it ftrace in 2.6.36-rc8 can trace the kthread? i want to trace the
kswapd/bdi_writeback_thread, but not success. i am sure that kswapd is
running, because i let the system eat huge memory. i can trace some
function such as __do_fault. what is issue on it? 

Best,
Figo.zhang


here is my ftrace script.
i = 1
while true;
do
	echo 1 > /proc/sys/kernel/ftrace_enabled
	echo function_graph > /sys/kernel/debug/tracing/current_tracer
	echo kswapd > /sys/kernel/debug/tracing/set_graph_function
	echo 1 > /sys/kernel/debug/tracing/tracing_on
	echo 1 > /sys/kernel/debug/tracing/tracing_enabled
	sleep 1
	echo 0 > /sys/kernel/debug/tracing/tracing_enabled
	cat /sys/kernel/debug/tracing/trace > ftrace.kswap.log.$i

	let i=i+1;

done