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Groups > linux.kernel > #1701599
| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: RCU stall when using function_graph |
| Date | 2017-08-02 02:20 +0200 |
| Message-ID | <u9Pyh-2wR-3@gated-at.bofh.it> (permalink) |
| References | <u9Nwt-1j6-5@gated-at.bofh.it> <u9NGa-1oh-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, 2 Aug 2017 00:15:44 +0200
Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
> On 02/08/2017 00:04, Paul E. McKenney wrote:
> >> Hi Paul,
> >>
> >> I have been trying to set the function_graph tracer for ftrace and each time I
> >> get a CPU stall.
> >>
> >> How to reproduce:
> >> -----------------
> >>
> >> echo function_graph > /sys/kernel/debug/tracing/current_tracer
> >>
> >> This error appears with v4.13-rc3 and v4.12-rc6.
Can you bisect this? It may be due to this commit:
0598e4f08 ("ftrace: Add use of synchronize_rcu_tasks() with dynamic trampolines")
-- Steve
> >>
> >> Is it something already reported ?
> >
> > I have seen this sort of thing, but only when actually dumping the trace
> > out, and I though those got fixed. You are seeing this just accumulating
> > the trace?
>
> No, just by changing the tracer. It is the first operation I do after
> rebooting and it is reproducible each time. That happens on an ARM64
> platform.
>
> > These RCU CPU stall warnings usually occur when something grabs hold of
> > a CPU for too long, as in 21 seconds or so. One way that they can happen
> > is excessive lock contention, another is having the kernel run through
> > too much data at one shot.
> >
> > Adding Steven Rostedt on CC for his thoughts.
> >
>
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Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-02 00:10 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-02 00:20 +0200
Re: RCU stall when using function_graph Steven Rostedt <rostedt@goodmis.org> - 2017-08-02 02:20 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-02 14:50 +0200
Re: RCU stall when using function_graph Steven Rostedt <rostedt@goodmis.org> - 2017-08-02 15:10 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-03 04:50 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-03 13:50 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-03 14:50 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-03 16:40 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-06 19:10 +0200
Re: RCU stall when using function_graph Pratyush Anand <panand@redhat.com> - 2017-08-09 11:20 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-09 15:00 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-09 15:30 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-09 16:50 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-09 18:00 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-09 19:30 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-10 11:50 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-10 23:40 +0200
Re: RCU stall when using function_graph Daniel Lezcano <daniel.lezcano@linaro.org> - 2017-08-11 11:40 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-02 19:00 +0200
Re: RCU stall when using function_graph "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-08-02 14:50 +0200
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