On 2011-07-20 14:11, Sasha Levin wrote: > Currently the method of dealing with an IO operation on a bus (PIO/MMIO) > is to call the read or write callback for each device registered > on the bus until we find a device which handles it. > > Since the number of devices on a bus can be significant due to ioeventfds > and coalesced MMIO zones, this leads to a lot of overhead on each IO > operation. > > Instead of registering devices, we now register ranges which points to > a device. Lookup is done using an efficient bsearch instead of a linear > search. > > This should speed up all IO operations generated by the guest. > > Cc: Avi Kivity <[email protected]> > Cc: Marcelo Tosatti <[email protected]> > Signed-off-by: Sasha Levin <[email protected]> > --- > > This patch depends on '[PATCH v3] MMIO: Make coalesced mmio use a device > per zone'. > > arch/x86/kvm/i8254.c | 4 +- > arch/x86/kvm/i8259.c | 4 +- > include/linux/kvm_host.h | 18 ++++---- > virt/kvm/coalesced_mmio.c | 6 +-- > virt/kvm/eventfd.c | 3 +- > virt/kvm/ioapic.c | 13 +----- > virt/kvm/kvm_main.c | 107 +++++++++++++++++++++++++++++++++++++++----- > 7 files changed, 115 insertions(+), 40 deletions(-) > > diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c > index efad723..61d193c 100644 > --- a/arch/x86/kvm/i8254.c > +++ b/arch/x86/kvm/i8254.c > @@ -713,13 +713,15 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 > flags) > kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); > > kvm_iodevice_init(&pit->dev, &pit_dev_ops); > - ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &pit->dev); > + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS, > + KVM_PIT_MEM_LENGTH, &pit->dev); > if (ret < 0) > goto fail; > > if (flags & KVM_PIT_SPEAKER_DUMMY) { > kvm_iodevice_init(&pit->speaker_dev, &speaker_dev_ops); > ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, > + KVM_SPEAKER_BASE_ADDRESS, 4, > &pit->speaker_dev); > if (ret < 0) > goto fail_unregister; > diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c > index 19fe855..c2295af 100644 > --- a/arch/x86/kvm/i8259.c > +++ b/arch/x86/kvm/i8259.c > @@ -562,7 +562,9 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm) > */ > kvm_iodevice_init(&s->dev, &picdev_ops); > mutex_lock(&kvm->slots_lock); > - ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &s->dev); > + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2, &s->dev); > + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev); > + ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev);
This made me wonder if you are incorrectly registering the same device multiple times. kvm_io_bus_register_dev is no longer optimally describing what is done here: the registration of an IO range with the bus. And that range is handled by a specific device. Conceptually, a device is only attached once to some bus. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
