Initialize new repository for holding IRQ tracing code examples

Signed-off-by: Alison Chaiken <alison@she-devel.com>

Author: chaiken

README.md

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+# irq-tracing
+Example code for tracing IRQs in Linux kernel
+Posted as part of Embedded Linux Conference talk, Tuesday, October 11, 2016,
+"IRQs: the Hard, the Soft, the Threaded and the Preemptible", http://sched.co/7rrr
+
+Tested on Boundary Devices Nitrogren i.MX6Q board with 4.4.4-rt11 kernel, but should work
+as intended on any recent PREEMPT_RT_FULL kernel with pinned Ethernet and CAN IRQs.
+
+To trigger NAPI path of execution, I did the following:
+-- started two instances of 'ping -f <board IP address>';
+-- ran a shell command that triggers dozens of scp's of a large file:
+   while true; do  scp /boot/vmlinuz root@<board ip addr>:/tmp; done
+After about 30 seconds, the kprobe indicating NAPI path is hit.
+
+
+I'd like to declare a license of GPLv2 or greater for this code, like the upstream Linux kernel,
+but apparently Github does not permit this.
+