i tried to remove the SA_SHIRQ option when request_irq(), unfortunately it seems that the IO-APIC will only try to allocate same # to it and once that slot is used, the request_irq will fail. ming On Fri, 2005-08-12 at 10:35 -0700, Bryan Henderson wrote: > >>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
