Re: high load with win7 & usb tablet

[Michael Tokarev <mjt@tls.msk.ru>]

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10.09.2010 16:19, Avi Kivity wrote:
>  On 09/03/2010 03:21 PM, Michael Tokarev wrote:
>> Hello.
>>
>> I noticed that window7, unlike windowsXP as I played with
>> previously, poses quite high load on host when idle.  On
>> my machine, host cpu usage is about 25% when one single-cpu
>> win7 guest is running with "-usbdevice tablet" option.
>> Here's a typical kvm_stats when such a guest is idling:
[]
> That's pretty good for an idle guest.

Hm.  Well.  Sometimes it goes "a bit" further than that:

 efer_reload                  0       0
 exits                  6307547   12445
 fpu_reload               39995      49
 halt_exits               74950      50
 halt_wakeup              72075      49
 host_state_reload      2150687    5585
 hypercalls                   0       0
 insn_emulation         3218768    6337
 insn_emulation_fail          0       0
 invlpg                       0       0
 io_exits                962906    5012
 irq_exits               190637     436
 irq_injections           31017       2
 irq_window                   0       0
 largepages                   0       0
 mmio_exits             1076036     496
 mmu_cache_miss           31812       9
 mmu_flooded                  0       0
 mmu_pde_zapped               0       0
 mmu_pte_updated              0       0
 mmu_pte_write             9818       9
 mmu_recycled                 0       0
 mmu_shadow_zapped        43946       0
 mmu_unsync                   0       0
 nmi_injections               0       0
 nmi_window                   0       0
 pf_fixed               2553881    5512
 pf_guest                     0       0
 remote_tlb_flush          4502       0
 request_irq                  0       0

It happens every few seconds, but it does not look like
this is the cause of high CPU load, most likely it's some
periodic tasks that really triggers every few secs, not
more often, so almost does not add to the average and min
loads.

> What does the guest think it is doing?  The Windows performance monitor?

Nothing.  It shows perfmon.exe using 3% CPU, and that's about
it.  I'm attaching a .png screenshot of the KVM window with
w7 perfmon running.  Unfortunately I don't have English
version handy, it's all in Russian, and I weren't able to
change system language to English.  But it is still readable.

During this shot, host CPU was about 30..35% in use - higher
than usual 25%, but I guess it's due to perfmon.

Also, I haven't found a way to see, for example, individual
interrupt activity in windows (like /proc/interrupts in
linux).

Thanks!

/mjt

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