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From: Kevin Locke <kevin@kevinlocke.name>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
	Christian Ehrhardt <christian.ehrhardt@canonical.com>
Subject: Re: qemu polling KVM_IRQ_LINE_STATUS when stopped
Date: Thu, 25 Jun 2020 14:10:46 -0600	[thread overview]
Message-ID: <20200625201046.GA179502@kevinolos> (raw)
In-Reply-To: <80754688-d05f-11a3-b25e-955b5ee0ca0b@redhat.com>

On Thu, 2020-06-25 at 21:17 +0200, Paolo Bonzini wrote:
> On 25/06/20 20:56, Kevin Locke wrote:
>>> Windows 10 can use the Hyper-V synthetic timer instead of the RTC, which
>>> shouldn't have the problem.
>>
>> That's great news!  Since I'm able to reproduce the issue on a
>> recently installed Windows 10 2004 VM on Linux 5.7 with QEMU 5.0, is
>> there anything I can do to help isolate the bug, or is it a known
>> issue?
> 
> You need to enable Hyper-V enlightenments, with something like
> 
> -cpu host,hv_vpindex,hv_runtime,hv_synic,hv_stimer,hv_reset,hv_time,hv_relaxed
> 
> on the QEMU command line.

Bingo!  I was using the defaults from virt-manager:[1]

-cpu $host,hv-time,hv-relaxed,hv-vapic,hv-spinlocks=0x1fff

Using to the enlightenments you suggested solves the high CPU when
paused issue for me.  After a bit of testing, it appears that
hv_stimer is the key.  High CPU when paused does not occur when that
enlightenment is enabled, regardless of which others are
enabled/disabled.

Is there any reason not to add it to the virt-manager defaults for
Windows 10?  Any other suggestions about which enlightenments to
enable or disable by default?

Thanks again,
Kevin

[1]: https://github.com/virt-manager/virt-manager/blob/v2.2.1/virtinst/domain/features.py#L74-L83

  reply	other threads:[~2020-06-25 20:10 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-17 21:34 qemu polling KVM_IRQ_LINE_STATUS when stopped Andi Kleen
2017-10-18  7:47 ` Paolo Bonzini
2017-10-18 17:49   ` Andi Kleen
2017-10-18 19:24     ` Paolo Bonzini
2017-10-20  0:34       ` Andi Kleen
2017-10-20  8:32         ` Paolo Bonzini
2017-10-20 14:09           ` Andi Kleen
2017-10-20 15:12             ` Paolo Bonzini
2017-10-20 20:50               ` Andi Kleen
2017-10-20 22:51                 ` Paolo Bonzini
2020-06-25 14:26                   ` Kevin Locke
2020-06-25 16:28                     ` Andi Kleen
2020-06-25 18:41                     ` Paolo Bonzini
2020-06-25 18:56                       ` Kevin Locke
2020-06-25 19:17                         ` Paolo Bonzini
2020-06-25 20:10                           ` Kevin Locke [this message]
2020-06-26 15:14                       ` Kevin Locke

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