Maybe related to a kernel 4.4 bug if you use windows10 and kernel 4.4
(proxmox will update the kernel to 4.4.8 soon)
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.4.8
commit 84f2443e213727323064e581e281d778831fa859
Author: Paolo Bonzini <pbonzini@redhat.com>
Date: Tue Mar 29 17:56:57 2016 +0200
KVM: x86: reduce default value of halt_poll_ns parameter
commit 14ebda3394fd3e5388747e742e510b0802a65d24 upstream.
Windows lets applications choose the frequency of the timer tick,
and in Windows 10 the maximum rate was changed from 1024 Hz to
2048 Hz. Unfortunately, because of the way the Windows API
works, most applications who need a higher rate than the default
64 Hz will just do
timeGetDevCaps(&tc, sizeof(tc));
timeBeginPeriod(tc.wPeriodMin);
and pick the maximum rate. This causes very high CPU usage when
playing media or games on Windows 10, even if the guest does not
actually use the CPU very much, because the frequent timer tick
causes halt_poll_ns to kick in.
There is no really good solution, especially because Microsoft
could sooner or later bump the limit to 4096 Hz, but for now
the best we can do is lower a bit the upper limit for
halt_poll_ns. :-(
Reported-by: Jon Panozzo <jonp@lime-technology.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
