Re: XP smp using a lot of CPU

[Kevin Shanahan <kmshanah@ucwb.org.au>]

On Wed, May 13, 2009 at 09:56:18AM +0300, Avi Kivity wrote:
> Ross Boylan wrote:
>> I just installed XP into a new VM, specifying -smp 2 for the machine.
>> According to top, it's using nearly 200% of a cpu even when I'm not
>> doing anything.
>>
>> Is this real CPU useage, or just a reporting problem (just as my disk
>> image is big according to ls, but isn't really)?
>>
>> If it's real, is there anything I can do about it?
>>
>> kvm 0.7.2 on Debian Lenny (but 2.6.29 kernel), amd64.  Xeon chips; 32
>> bit version of XP pro installed, now fully patched (including the
>> Windows Genuine Advantage stuff, though I cancelled it when it wanted to
>> run).  
>>
>> Task manager in XP shows virtually no CPU useage.
>>
>> Please cc me on responses.
>>
>>   
>
> I'm guessing Windows uses a pio port to sleep, which kvm doesn't  
> support.  Can you provide kvm_stat output?

Could this be what has happened to Windows 2000 as well? (kvm-Bugs-2314737)

Task manager in the guest shows both CPUs idle, but on the host it
shows 200% CPU almost constantly.

ucwb-0119:/home/kmshanah/kvm/kvm-85# ./kvm_stat -1
efer_reload                    0         0
exits                 5454894602      4839
fpu_reload               5311150         5
halt_exits                200719         1
halt_wakeup               200218         1
host_state_reload     1951410204      1869
hypercalls                     0         0
insn_emulation        1391377570      1393
insn_emulation_fail           52         0
invlpg                  92034019         1
io_exits              1042421930       694
irq_exits             1545221935      1874
irq_injections         450100320       448
irq_window             225291775       245
kvm_request_irq                0         0
largepages                     0         0
mmio_exits                484805         0
mmu_cache_miss          26346459         4
mmu_flooded             21532314         4
mmu_pde_zapped            886970         0
mmu_pte_updated         52882039         4
mmu_pte_write           70044961         6
mmu_recycled                1102         0
mmu_shadow_zapped       26384127         4
mmu_unsync                  7671         0
mmu_unsync_global              0         0
nmi_injections                 0         0
nmi_window                     0         0
pf_fixed               421444565       167
pf_guest                34545643         1
remote_tlb_flush       125039581         9
request_nmi                    0         0
signal_exits                   1         0
tlb_flush              749126829       284

Regards,
Kevin.