On Fri, Jul 11, 2008 at 03:06:33AM -0700, Eric W. Biederman wrote: > Matthew Wilcox <matthew@xxxxxx> writes: > > > I'd like to thank Michael Ellerman for his feedback. This is a much > > better patchset than it used to be. > > There is a reason we don't have an API to support this. Linux can not > reasonably support this, especially not on current X86. The designers > of the of the AHCI were idiots and should have used MSI-X. > > Attempting to support multiple irqs in an MSI capability breaks > every interesting use of an irq. > > mask/unmask is will likely break because the mask bit is optional > and when it is not present we disable the msi capability. > > We can not set the affinity individually so we can not allow > different queues to be processed on different cores. > > So in general it seems something that we have to jump through a million > hurdles and the result is someones twisted parody of a multiple working > irqs, that even Intel's IOMMU can't cure. With interrupt-remapping, we can program the individual interrupt remapping table entries to point to different cpu's etc. All we have to take care is, do the IRTE allocation in a consecutive block and program the starting index to the MSI registers. Just curious Eric, why do you think that won't work? thanks, suresh > So unless the performance of the AHCI is better by a huge amount I don't > see the point, and even then I am extremely sceptical. > > Eric -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
