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Description of problem:
Invalid warning about number of hotpluggable cpus
Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.10.0-4.el7.ppc64le
How reproducible:
100%
Steps to Reproduce:
1.Boot up guest with command:
/usr/libexec/qemu-kvm \
-smp 240,sockets=1,cores=30,threads=8 \
-m 4096 \
-nodefaults \
-device nec-usb-xhci,id=xhci \
-device usb-tablet,id=tablet \
-device usb-kbd,id=kbd \
-device virtio-scsi-pci,bus=pci.0 \
-device scsi-hd,id=scsi-hd0,drive=scsi-hd0-dr0,bootindex=0 \
-drive file=rhel75-ppc64le-virtio.qcow2,if=none,id=scsi-hd0-dr0,format=qcow2,cache=none \
-device virtio-net-pci,netdev=net0,id=nic0,mac=52:54:00:c4:e7:84 \
-netdev tap,id=net0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,vhost=on \
-monitor stdio \
2.
3.
Actual results:
Warning: Number of SMP cpus requested (240) exceeds the recommended cpus supported by KVM (192)
Warning: Number of hotpluggable cpus requested (240) exceeds the recommended cpus supported by KVM (192)
QEMU 2.10.0 monitor - type 'help' for more information
(qemu) VNC server running on ::1:5900
Expected results:
there is no hotpluggable cpus,should remove this warning.it should display when use maxcpus=240.
Additional info:
ppc only
So this isn't actually ppc specific. It's just that the message is more likely to be triggered on ppc, because we have a recommended max vcpu count which depends on the number of host cpus.
Looks like the code in qemu which gives this message comes from Andrew Jones - reassigning to him.
(In reply to Xujun Ma from comment #0)
> Actual results:
> Warning: Number of SMP cpus requested (240) exceeds the recommended cpus
> supported by KVM (192)
> Warning: Number of hotpluggable cpus requested (240) exceeds the recommended
> cpus supported by KVM (192)
The above appears to be working as designed.
>
> Expected results:
> there is no hotpluggable cpus,should remove this warning.it should display
> when use maxcpus=240.
Ah, so the complaint isn't that the 'SMP' warning is issued, or even that the 'hotpluggable' warning should be issued when maxcpus=240, but that the 'hotpluggable' warning is issued when maxcpus isn't specified on the command line. That's an incorrect expectation. The way the -smp command line works is that max_cpus defaults to smp_cpus when it is not provided, e.g. '-smp 240' is equivalent to '-smp 240,maxcpus=240'
Thanks,
drew