On 04/30/2011 08:00 PM, Chris Thompson wrote:
I'm trying to add a trace to qemu-kvm that will log the value of the
vcpu's clock when a specific interrupt gets pushed. I'm working with
qemu-kvm-0.14.0 on the 2.6.32-31 kernel. I've added the following to
kvm_arch_try_push_interrupts in qemu-kvm-x86.c:
if (irq == 41) {
// Get the VCPU's TSC
struct kvm_clock_data clock;
kvm_vcpu_ioctl(env, KVM_GET_CLOCK, &clock);
uint64_t ticks = clock.clock;
trace_kvm_clock_at_injection(ticks);
}
This mechanism is only active with -no-kvm-irqchip; otherwise interrupt
injection happens in the kernel.
And here's the trace event I added:
kvm_clock_at_injection(uint64_t ticks) "interrupt 41 at clock %"PRIu64""
I have that trace and the virtio_blk_req_complete trace enabled. An
excerpt from the resulting trace output from simpletrace.py:
virtio_blk_req_complete 288390365546367 30461.681 req=46972352 status=0
kvm_clock_at_injection 288390365546578 0.211 ticks=46972352
virtio_blk_req_complete 288390394870065 29323.487 req=46972352 status=0
kvm_clock_at_injection 288390394870276 0.211 ticks=46972352
Am I getting the guest's clock incorrectly? And even if so, why is it
the same as the request pointer that virtio_blk_req_complete reports?
Any ideas are appreciated.
What is the 'ticks' field?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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