This patch series optimizes irq data path of piix_pci. So far piix3 tracks each pirq level and checks whether a given pic pins is asserted by seeing if each pirq is mapped into the pic pin. This is independent on irq routing, but data path is on slow path.
Given that irq routing is rarely changed and asserting pic pins is on data path, the path that asserts pic pins should be optimized and chainging irq routing should be on slow path. The new behavior with this patch series is to use bitmap which is addressed by pirq and pic pins with a given irq routing. When pirq is asserted, the bitmap is set and see if the pic pins is asserted by checking the bitmaps. When irq routing is changed, rebuild the bitmap and re-assert pic pins. Changes v2 -> v3: - s/dummy_for_save_load_compat/pci_irq_levels_vmstate/g - move down unused member of pci_irq_levels_vmstate in the structure for cache efficiency Changes v1 -> v2: - addressed review comments. Isaku Yamahata (3): pci: add accessor function to get irq levels piix_pci: eliminate PIIX3State::pci_irq_levels piix_pci: optimize set irq path hw/pci.c | 7 +++ hw/pci.h | 1 + hw/piix_pci.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++--------- 3 files changed, 108 insertions(+), 19 deletions(-)
