>>How much extra work does Linux have to do for each interrupt? > >usually 1 pci mmio read; the rest is negligible. I was hoping you would cater better to my ignorance of how PCI interrupt handling works in Linux. Is it the case that Linux invokes the registered interrupt handler of each of the drivers for the devices that share the interrupt, and each does an mmio read of its device to find out if it had reason to generate an interrupt? So the waste is that extra call, and you're saying the CPU instructions involved are negligible compared to the mmio read? Are these level-sensitive interrupts, so that if both devices need service at the same time, they generate just one interrupt and neither device driver call is wasted? - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
