On Wed, 30 Oct 2013 15:39:50 -0700 Kenneth Lee <nek.in...@gmail.com> wrote:
> Dear Steven, > > I want to add a new function to ftrace subsystem. Sometimes, we will face > such a problem: system do not response to the input on time one to two times > everyday. It is not easy to capture because it rarely happens. So I want to > add a function to the kernel. If I have such problem, I insert a kernel > module, who add a hook to the position that receive the input and another to > the position that response to the input (with a session id if necessary). And > I can compare the time between them and if the period is longer then a > pre-set threshold, I can give a signal to a user helper application (maybe a > script waiting on the file), which then can save the trace event to a file > for later inspection. I'm a little confused in what you want. > > > > The user helper script may look like this: > > > > #/bin/sh > > > > echo ‘sched:*’ > /sys/kernel/debug/tracing/set_event > > modprobe delay_inspector.ko threshold=500 > > cat /sys/kernel/debug/tracing/waiter #wait for signal > > cp /sys/kernel/debug/tracing/trace /var/log/delay_infomation > > > > > > It looks like a standalone function. But I don’t have place to put it. Do you > think I can implement it in ftrace? And do you think if there are better > solution? > You want something to wake up if it takes too long before an event happens? If so, why not just use a select() on the trace_pipe and if it times out, then dump the trace. You can even set up a separate instance. (this is waiting for a schedule switch to pid 1) cd /sys/kernel/debug/tracing mkdir instances/mine echo 'next_pid == 1' > instances/mine/events/sched/sched_switch/filter echo 1 > instances/mine/events/sched/sched_switch/enable The in a userspace program, I open "instances/mine/events/trace_pipe" and run a select() on that file descriptor with a given timeout. If the event does not happen within the expected time frame, the select returns zero, and this userspace program can deal with it. Is that the functionality you are trying to achieve? -- Steve -- 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/
