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SubjectRe: [crash] Re: [PATCH 1/3] tracing/function-graph-tracer: introduce __notrace_funcgraph to filter special functions

* Steven Rostedt <rostedt@goodmis.org> wrote:

>
> On Tue, 9 Dec 2008, Fr?d?ric Weisbecker wrote:
> > 2008/12/9 Fr?d?ric Weisbecker <fweisbec@gmail.com>:
> >
> >
> > I built this config on an smp x86-64 and booted several times (and
> > tested the function tracer manually) with and without the following
> > options:
> >
> > initcall_debug apic=verbose sysrq_always_enabled ignore_loglevel
> > selinux=0 nmi_watchdog=2 idle=poll
> >
> > And I can't reproduce this bug.... That might be a very nasty race condition...
>
> Neither can I :-(
>
> Ingo, is this on the box that stresses NMIs?

yes. You could try to inject even more NMIs than i normally do,
artificially, by picking up tip/master and running KernelTop with a
100,000 cycles IRQ interval:

http://redhat.com/~mingo/perfcounters/kerneltop.c

run it like this:

./kerneltop -c 100000

and run an infinite loop per process:

while :; do :; done &

to get the NMIs going intensely:

------------------------------------------------------------------------------
KernelTop: 115437 irqs/sec [NMI, 100000 cycles], (all, 16 CPUs)
------------------------------------------------------------------------------

events RIP kernel function
______ ______ ________________ _______________

81224.00 - ffffffffff6001a4 : vread_hpet
3119.00 - ffffffff8027cf99 : perf_read
2484.00 - ffffffff802227d5 : read_hpet
1157.00 - ffffffff8056b69a : mutex_lock
1041.00 - ffffffffff600000 : vgettimeofday
986.00 - ffffffff80333db5 : avc_has_perm_noaudit
896.00 - ffffffff8026be2d : audit_syscall_exit
653.00 - ffffffff8056c8f5 : _spin_lock
577.00 - ffffffff802ecd14 : dnotify_parent
528.00 - ffffffff8033679c : file_has_perm
489.00 - ffffffff802bc060 : dput
470.00 - ffffffff8026c366 : audit_syscall_entry


Ingo


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