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On Mon, Jun 06, 2005 at 07:53:55PM -0400, Jeff Garzik wrote: > Greg KH wrote: > >On Mon, Jun 06, 2005 at 07:08:33PM -0400, Jeff Garzik wrote: > > > >>Greg KH wrote: > >> > >>>Why would it matter? The driver shouldn't care if the interrupts come > >>>in via the standard interrupt way, or through MSI, right? And if it > >> > >>It matters. > >> > >>Not only the differences DaveM mentioned, but also simply that you may > >>assume your interrupt is not shared with anyone else. > > > > > >Ok, and again, how would the call, pci_in_msi_mode(struct pci_dev *dev) > >not allow for the driver to determine this? > > Let me see if I understand this correctly :) > > A technology (MSI) allows one to more efficiently call interrupt > handlers, with fewer bus reads... and you want to add a test to each > interrupt handler -- a test which adds several bus reads to the hot path > of every MSI driver? hell no. > We want to -decrease- the overhead involved with an interrupt, but > pci_in_msi_mode() increases it. No, just call pci_in_msi_mode() where you were previously calling pci_enable_msi() to test to see if we are in msi mode. Patches in a bit to hopefully better show what I am talking about... thanks, greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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