[Xen-devel] [PATCH] Reuse irq number for virq/ipi after vcpu unplug/plug

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

Irq nunmber for per-vcpu event (virq/ipi) needs kept
accross vcpu plug/unplug, once allocated. We just 
reuse this irq number and bind it to a new event port.
Or else, /proc/interrupt exports messed statistics 
like:

ot@localhost ~]# cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3
256:     423066          0          0          0     Dynamic-irq  timer0
257:       3014          0          0          0     Dynamic-irq
resched0
258:         37          0          0          0     Dynamic-irq
callfunc0
259:        713          0          0          0     Dynamic-irq  xenbus
260:        343       1323         65         50     Dynamic-irq
xencons
261:        270         62          0          0     Dynamic-irq  blkif
262:          0    1053818       1220        855     Dynamic-irq
resched1
263:          0          0       2165         53     Dynamic-irq
callfunc1
264:          0       3218         69          0     Dynamic-irq  timer1
265:          0          0      42768        228     Dynamic-irq
resched2
266:          0         45          0       1867     Dynamic-irq
callfunc2
267:          0          0      39543        256     Dynamic-irq  timer2
268:          0       2244         46      33027     Dynamic-irq
resched3
269:       1585          0          0          0     Dynamic-irq
callfunc3
270:      11273          0       1885       1073     Dynamic-irq  timer3
NMI:          0          0          0          0
LOC:          0          0          0          0
ERR:          0
MIS:          0

You can see from above that each virq/ipi have 
statistics on several vcpus, when that data on 
other vcpus belong to other virq/ipi before unplug.

This also applies to save/restore for same issue.

Signed-off-by Kevin Tian <kevin.tian@xxxxxxxxx>

Attachment: reuse_irq_for_virq_ipi.patch
Description: reuse_irq_for_virq_ipi.patch

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