shared irqs and performance

[Gary Aitken]

On my 4.10 system, I added in a third ethernet device.

However, I see from dmesg that the irq assigned is shared with my
scsi controller:

de1: <Digital 21041 Ethernet> port 0xf880-0xf8ff mem
   0xfdfffc00-0xfdfffc7f irq 9 at device 16.0 on pci0
bt0: <Buslogic Multi-Master SCSI Host Adapter> port 0xfcec-0xfcef
   irq 9 at device 17.0 on pci0

Since the driver was already present, things went ok, in the sense
that the system booted and scsi devices still work.

1.  Will this work reliably (I haven't actually hooked anything
     to the new network card yet)?
2.  Even if it does work, I assume it would be better to force
     it to an unused irq for performance reasons?

Thanks,

Gary