(systemtap)
probe module("vfio_iommu_type1").function("vfio_iommu_type1_ioctl") {
printf("New vfio_iommu_type1_ioctl\n");
start_stopwatch("vfioioctl");
}
probe module("vfio_iommu_type1").function("vfio_iommu_type1_ioctl").return {
timer=read_stopwatch_ns("vfioioctl")
printf("Completed vfio_iommu_type1_ioctl: %d\n", timer);
stop_stopwatch("vfioioctl");
}
probe module("vfio_iommu_type1").function("vfio_pin_pages_remote") {
timer=read_stopwatch_ns("vfioioctl")
printf("%ld: %s\n", timer, $$parms);
}
The overhead was significant enough, the fast case this time was 132 seconds.
The following slow case had 209 seconds (still slower but not more by factors).
While the overhead might have influenced the absolute timing of this too much.
It still might help indicate the size/frequency distribution of these calls
that we wanted to know.
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Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1838575
Title:
passthrough devices cause >17min boot delay
Status in linux package in Ubuntu:
Confirmed
Status in qemu package in Ubuntu:
Incomplete
Bug description:
Adding passthrough devices to a guest introduces a boot delay of > 17
minutes. During this time libvirt reports the guest to be "paused".
The delay does not seem to scale with the # of hostdevs - that is, 1
hostdev causes about a 17min delay, while 16 only bumps that up to
~18min. Removing all hostdevs avoids the delay.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1838575/+subscriptions
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