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@ctheune
Last active December 24, 2015 23:58
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Debugging kernel issues with perf. Specifically used some of those for debugging our KVM networking issue. Extracted from instructions here: http://comments.gmane.org/gmane.comp.emulators.kvm.devel/113211
This is using perf 3.4 which seems to be a little old and missing some options.
Establish probes and start recording:
$ perf probe start_xmit
$ perf probe virtqueue_kick
$ perf record -a -e net:net_dev_xmit -e net:net_dev_queue -e probe:start_xmit -e probe:virtqueue_kick -R&
[...attempt to transmit packets inside guest...]
$ kill %1
$ perf script -i perf.data
Built kernel with CONFIG_DYNAMIC_DEBUG=y
$ echo -n 'module virtio_net +p' > /sys/kernel/debug/dynamic_debug/control
$ echo -n 'module virtio +p' >/sys/kernel/debug/dynamic_debug/control
$ echo 8 > /proc/sys/kernel/printk
Generating a core file
$ gdb
(gdb) generate-core-file [file]
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