Messages in this thread | | | Date | Thu, 4 Mar 2010 13:10:16 +0800 | Subject | Re: 2.6.33: ftrace triggers soft lockup | From | Américo Wang <> |
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On Thu, Mar 4, 2010 at 11:18 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > On Thu, 2010-03-04 at 11:01 +0800, Américo Wang wrote: > >> > >> > So it is stuck in stop machine. I wonder where exactly. I see some do_exit >> > at the top but I wonder how much they are reliable. >> >> Well, I think 'kstop' is just random, sometimes I got 'watchdog' or some other >> process. >> >> > >> > Anyway, as Steve said, we really need a full config to reproduce it. >> > >> >> Done in another reply. > > Thanks! > > Frederic, I notice that lockdep is on, did anything change that might > slow down the code in lockdep, or is the function graph tracer doing > more locking? > > I'm betting that we are hitting a live lock. That is, an interrupt goes > off, it is being traced, and the function graph is tracing it, but some > locking is happening (although it also tracks disabling of interrupts) > and this slows the interrupt handler down enough that when it finishes, > another interrupt goes off. > > Américo, > > Could you disable LOCKDEP and see if you still encounter this lockup? >
Sure, after disabling LOCKDEP, I can't see the warning, _but_ the system is still as unacceptablly slow as when LOCKDEP was enabled.
So I am afraid the problem is still there.
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