irqbalance_mck: replace extra service with service drop-in

Using a drop-in instead of an extra service avoids having to juggle
between both services (especially since irqbalance_mck did not have a
Conflict=irqbalance.service statement)

That way, we only have a single service to check for (irqbalance.service),
and system administrators should find this less confusing if they normally
rely on irqbalance.

The drop-in is also installed in /run so will automatically disappear in
the event of a linux crash or a reboot without shutting down mckernel

Change-Id: I004f4f25d9ca037e411e0bc91f4555db138ecfef

scripts/irqbalance_mck.in

@@ -0,0 +1,28 @@
+# irqbalance is a daemon process that distributes interrupts across
+# CPUS on SMP systems. The default is to rebalance once every 10
+# seconds. This is the environment file that is specified to systemd via the
+# EnvironmentFile key in the service unit file (or via whatever method the init
+# system you're using has.
+#
+# ONESHOT=yes
+# after starting, wait for a minute, then look at the interrupt
+# load and balance it once; after balancing exit and do not change
+# it again.
+#IRQBALANCE_ONESHOT=
+
+#
+# IRQBALANCE_BANNED_CPUS
+# 64 bit bitmask which allows you to indicate which cpu's should
+# be skipped when reblancing irqs. Cpu numbers which have their
+# corresponding bits set to one in this mask will not have any
+# irq's assigned to them on rebalance
+#
+IRQBALANCE_BANNED_CPUS=%mask%
+
+#
+# IRQBALANCE_ARGS
+# append any args here to the irqbalance daemon as documented in the man page
+#
+IRQBALANCE_ARGS=--banirq=%banirq%
+
+