From 743eeb0b01d2fbf4154bf87bff1ebb6fb18aeb7a Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Wed, 27 Jul 2011 16:00:48 +0300 Subject: 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 Cc: Marcelo Tosatti Signed-off-by: Sasha Levin Signed-off-by: Avi Kivity --- arch/x86/kvm/irq.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 53e2d084bff..2086f2bfba3 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -66,7 +66,9 @@ struct kvm_pic { struct kvm *kvm; struct kvm_kpic_state pics[2]; /* 0 is master pic, 1 is slave pic */ int output; /* intr from master PIC */ - struct kvm_io_device dev; + struct kvm_io_device dev_master; + struct kvm_io_device dev_slave; + struct kvm_io_device dev_eclr; void (*ack_notifier)(void *opaque, int irq); unsigned long irq_states[16]; }; -- cgit v1.2.3