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| author | Sasha Levin <levinsasha928@gmail.com> | 2011-07-27 16:00:48 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-09-25 19:17:59 +0300 |
| commit | 743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a (patch) | |
| tree | 5392464930f7e77131d65f32ba96ce4665307629 /arch/x86/kvm/x86.c | |
| parent | 0d460ffc0956d2dbe12ca9f5f6aa0f8701ea9d73 (diff) | |
| download | lwn-743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a.tar.gz lwn-743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a.zip | |
KVM: Intelligent device lookup on I/O bus
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.
Performance test was conducted by comparing exit count per second with
200 ioeventfds created on one byte and the guest is trying to access a
different byte continuously (triggering usermode exits).
Before the patch the guest has achieved 259k exits per second, after the
patch the guest does 274k exits per second.
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6cb353c83a12..d28dff749dfd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3562,7 +3562,11 @@ long kvm_arch_vm_ioctl(struct file *filp, if (r) { mutex_lock(&kvm->slots_lock); kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, - &vpic->dev); + &vpic->dev_master); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, + &vpic->dev_slave); + kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, + &vpic->dev_eclr); mutex_unlock(&kvm->slots_lock); kfree(vpic); goto create_irqchip_unlock; |