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SubjectRe: [PATCH V5 0/3] introduce coalesced pio support
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On 14/10/2018 01:09, Peng Hao wrote:
> Coalesced pio is based on coalesced mmio and can be used for some port
> like rtc port, pci-host 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 starting and closing a virtual machine, it will access pci-host config
> port frequently. So setting these port as coalesced pio can reduce startup
> and shutdown time.
>
> 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:POUT 86 30.99% 74.59% 9us 29us 10.75us (+- 3.41%)
> 0xcf8:POUT 1119 2.60% 2.12% 2.79us 56.83us 3.41us (+- 2.23%)
>
> with my patch
> IO Port Access Samples Samples% Time% Min Time Max Time Avg time
> 0x70:POUT 106 32.02% 29.47% 0us 10us 1.57us (+- 7.38%)
> 0xcf8:POUT 1065 1.67% 0.28% 0.41us 65.44us 0.66us (+- 10.55%)
>
>
> Peng Hao (3):
> kvm/x86 : add coalesced pio support
> kvm/x86 : add document for coalesced mmio
> kvm/x86 : add document for coalesced pio
>
> Documentation/virtual/kvm/api.txt | 28 +++++++++++++++++++++++++++
> include/uapi/linux/kvm.h | 11 +++++++++--
> virt/kvm/coalesced_mmio.c | 12 +++++++++---
> virt/kvm/kvm_main.c | 2 ++
> 4 files changed, 48 insertions(+), 5 deletions(-)
>

Queued, thanks (squashing 1 and 3 together).

Paolo

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