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author | Sasha Levin <levinsasha928@gmail.com> | 2011-07-27 15:00:48 +0200 |
---|---|---|
committer | Avi Kivity <avi@redhat.com> | 2011-09-25 18:17:59 +0200 |
commit | 743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a (patch) | |
tree | 5392464930f7e77131d65f32ba96ce4665307629 /include | |
parent | KVM: Use __print_symbolic() for vmexit tracepoints (diff) | |
download | linux-743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a.tar.xz linux-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 'include')
-rw-r--r-- | include/linux/kvm_host.h | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ff4d4062af9d..d0e42f30edf6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -55,16 +55,16 @@ struct kvm; struct kvm_vcpu; extern struct kmem_cache *kvm_vcpu_cache; -/* - * It would be nice to use something smarter than a linear search, TBD... - * Thankfully we dont expect many devices to register (famous last words :), - * so until then it will suffice. At least its abstracted so we can change - * in one place. - */ +struct kvm_io_range { + gpa_t addr; + int len; + struct kvm_io_device *dev; +}; + struct kvm_io_bus { int dev_count; #define NR_IOBUS_DEVS 300 - struct kvm_io_device *devs[NR_IOBUS_DEVS]; + struct kvm_io_range range[NR_IOBUS_DEVS]; }; enum kvm_bus { @@ -77,8 +77,8 @@ int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, const void *val); int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, int len, void *val); -int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, - struct kvm_io_device *dev); +int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, + int len, struct kvm_io_device *dev); int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, struct kvm_io_device *dev); |