From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Reinoud Zandijk <reinoud@netbsd.org>
Cc: qemu-devel@nongnu.org
Subject: Re: Win10 always takes 100% cpu power even when idle
Date: Wed, 17 Mar 2021 16:18:53 +0000 [thread overview]
Message-ID: <YFIr7YJvjGXURoRl@redhat.com> (raw)
In-Reply-To: <YFIqKhlRclmy+kwN@diablo.13thmonkey.org>
On Wed, Mar 17, 2021 at 05:11:22PM +0100, Reinoud Zandijk wrote:
> Hi,
>
> when executing Qemu with
>
> qemu-system-x86_64 -m 4G -smp cores=2 -M q35 -snapshot \
> -drive file=/home/reinoud/Downloads/Win10-demo.raw,format=raw \
> -rtc base=localtime,clock=host -spice port=5924,disable-ticketing=on \
> -vga qxl -usb -device usb-tablet -net nic -net tap,ifname=tap0,script=no
>
> my cpu usage in Windows10 *allways* reports 100% cpu usage. On the host system
> its always 190%+ ie it is really taking two cores completely.
>
> Using our NVMM accelerator makes it run a whole lot faster, as good as native
> speed, but it always takes up the whole two processors too! Windows10 also
> *allways* reports 100% cpu usage. Its not a startup thing for even when
> letting it run for quite some time never reduces the cpu time.
>
> In contrast, running NetBSD in the VM takes no CPU time at all when idle.
>
> When Googling about this, I saw this come by quite often. Is there something
> Qemu can do about this? What makes it spin like this and why is it Windows10
> specific? This is a specific VM aware version too if I may believe it saying
> so. I already replaced drivers to virtio etc but to no avail. Always 100% CPU
> time for all CPUs.
>
> Could this also be an ACPI thing?
IIRC, "-usb" still adds a USB-1 controller and that's known to be bad
for causing high load in Windows guests in particular. So before
debugging anything else, I'd suggest configuring a USB-3 controller
instead - see docs/usb2.txt XHCI info.
Regards,
Daniel
--
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next prev parent reply other threads:[~2021-03-17 16:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 16:11 Win10 always takes 100% cpu power even when idle Reinoud Zandijk
2021-03-17 16:18 ` Daniel P. Berrangé [this message]
2021-03-17 17:00 ` Reinoud Zandijk
2021-03-17 17:05 ` Daniel P. Berrangé
2021-03-17 21:29 ` Reinoud Zandijk
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