[Bug] Boot timer seems off #4429
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Boot timer calculations do not match my expectations
When running a minimal Linux kernel in firecracker, on x86_64, the measured boot time seems off.
To Reproduce
Run this program as
/init
(creates the /mem char dev)Use this config (though I don't think it's relevant):
Start firecracker with
Command output
Case 1, SMP kernel:
Case 2, no-SMP kernel:
Expected behaviour
In case 1, I'd expect the
Guest-boot-time
to be 33ms, as that's how much time elapsed between the startup time and the message being sent.If the measurement includes the VM creation time, then 78ms still doesn't make sense, as
ts
is measuring 70ms.Similarly for case 2, I'd expect 8ms for the
Guest-boot-time
and 32ms for the guest boot + VM creation, instead of 43ms.Environment
Additional context
I'm trying to measure boot times with more accuracy than using
ts
offsets, but the results don't seem to line up.I've not yet looked into the source code for possible reasons.
Checks
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