[Qemu-devel] [PATCH V5 0/4] introduce coalesced pio support
Coalesced pio is base on coalesced mmio and can be used for some port like rtc port, pci-host config port, virtio-pci config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When it starts and closes the virtual machine, it will access pci-host config port or virtio-pci config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. In qemu I just realize piixfx's pci-host, it is convenient for other pci-host type implementations. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT86 30.99%74.59% 9us 29us10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 10632.02%29.47%0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 10651.67% 0.28% 0.41us65.44us 0.66us (+- 10.55%) These are just qemu's patches, another patches are for kernel. Changes v4 --> v5: update kvm header, improve compatibility. Changes v3 --> v4 modify coalesced_mmio_{add|del} to coalesced_io_{add|del} delete unnecessary macro define Peng Hao (4): target-i386: introduce coalesced_pio kvm header update target-i386: add coalesced_pio API target-i386: add rtc 0x70 port as coalesced_pio target-i386: add i440fx 0xcf8 port as coalesced_pio accel/kvm/kvm-all.c | 61 ++- hw/pci-host/piix.c| 4 hw/timer/mc146818rtc.c| 8 +++ include/exec/memory.h | 4 ++-- linux-headers/linux/kvm.h | 11 +++-- memory.c | 4 ++-- 6 files changed, 80 insertions(+), 12 deletions(-) -- 1.8.3.1
[Qemu-devel] [PATCH V5 0/4] introduce coalesced pio support
Coalesced pio is base on coalesced mmio and can be used for some port like rtc port, pci-host config port, virtio-pci config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When it starts and closes the virtual machine, it will access pci-host config port or virtio-pci config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. In qemu I just realize piixfx's pci-host, it is convenient for other pci-host type implementations. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT86 30.99%74.59% 9us 29us10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 10632.02%29.47%0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 10651.67% 0.28% 0.41us65.44us 0.66us (+- 10.55%) These are just qemu's patches, another patches are for kernel. Changes v4 --> v5: update kvm header, improve compatibility. Changes v3 --> v4 modify coalesced_mmio_{add|del} to coalesced_io_{add|del} delete unnecessary macro define Peng Hao (4): target-i386: introduce coalesced_pio kvm header update target-i386: add coalesced_pio API target-i386: add rtc 0x70 port as coalesced_pio target-i386: add i440fx 0xcf8 port as coalesced_pio accel/kvm/kvm-all.c | 61 ++- hw/pci-host/piix.c| 4 hw/timer/mc146818rtc.c| 8 +++ include/exec/memory.h | 4 ++-- linux-headers/linux/kvm.h | 11 +++-- memory.c | 4 ++-- 6 files changed, 80 insertions(+), 12 deletions(-) -- 1.8.3.1