Hi, Thanks to Q35/PCIe, we can now assign a large number of PCI devices to a single VM, but it seems that Flatview rendering scales poorly (worse than linear) when it has to deal with a large number of Memory Regions.
I've measured to cost of the pci_default_write_config() call at virtio_write_config() for 1 PCI device vs. 100 PCI devices: - 1 PCI device write_config: 1879 us write_config: 1037 us write_config: 1 us write_config: 3 us write_config: 1783 us write_config: 2652 us write_config: 1 us write_config: 2 us write_config: 1551 us - 100 PCI devices write_config: 503963 us write_config: 1 us write_config: 493344 us write_config: 0 us write_config: 472946 us write_config: 1 us write_config: 495175 us write_config: 1 us write_config: 519312 us write_config: 1 us I guess this is a consequence of having to reset/rebuild the Flatview when altering the PCI BAR regions. Is this a known issue we're already working on? Thanks, Sergio (slp).
