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authorMarcelo Tosatti <mtosatti@redhat.com>2008-09-24 20:28:34 -0300
committerAvi Kivity <avi@redhat.com>2008-10-15 14:25:28 +0200
commite48258009d941891fca35348986b8d280caf31cd (patch)
tree73d1fb56a9fc22c1e55160bb04e772bd6b2244fb /virt/kvm/kvm_main.c
parent582801a95d2f2ceab841779e1dec0e11dfec44c0 (diff)
KVM: PIC: enhance IPI avoidance
The PIC code makes little effort to avoid kvm_vcpu_kick(), resulting in unnecessary guest exits in some conditions. For example, if the timer interrupt is routed through the IOAPIC, IRR for IRQ 0 will get set but not cleared, since the APIC is handling the acks. This means that everytime an interrupt < 16 is triggered, the priority logic will find IRQ0 pending and send an IPI to vcpu0 (in case IRQ0 is not masked, which is Linux's case). Introduce a new variable isr_ack to represent the IRQ's for which the guest has been signalled / cleared the ISR. Use it to avoid more than one IPI per trigger-ack cycle, in addition to the avoidance when ISR is set in get_priority(). Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt/kvm/kvm_main.c')
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