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[Qemu-devel] [Bug 1811533] Re: Unstable Win10 guest with qemu 3.1 + huge
From: |
Damir |
Subject: |
[Qemu-devel] [Bug 1811533] Re: Unstable Win10 guest with qemu 3.1 + huge pages + hv_stimer |
Date: |
Wed, 07 Aug 2019 19:13:20 -0000 |
Still broken with Qemu 4.1rc2 /w Kernel 5.2.
This is a huge problem, as it breaks performance, either in networking
(you can't use the virtio net which is the only 100G adapter afaik), or
you have to disable huge pages, which is a blow to any large vm host, or
it breaks stimer, which increases cpu usage, generally breaking
virtualization.
Thank you!
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https://bugs.launchpad.net/bugs/1811533
Title:
Unstable Win10 guest with qemu 3.1 + huge pages + hv_stimer
Status in QEMU:
New
Bug description:
Host:
Gentoo linux x86_64, kernel 4.20.1
Qemu 3.1.0
CPU: Intel i7 6850K
Chipset: X99
Guest:
Windows 10 Pro 64bit (1809)
Machine type: pc-q35_3.1
Hyper-V enlightenments:
hv_stimer,hv_reenlightenment,hv_frequencies,hv_vapic,hv_reset,hv_synic,hv_runtime,hv_vpindex,hv_time,hv_relaxed,hv_spinlocks=0x1fff
Memory: 16GB backed by 2MB huge pages
Issue:
Once guest is started, log gets flooded with:
qemu-system-x86_64: vhost_region_add_section: Overlapping but not
coherent sections at 103000
or
qemu-system-x86_64: vhost_region_add_section:Section rounded to 0
prior to previous 1f000
(line endings change)
and as time goes guest loses network access (virtio-net-pci) and
general performance diminishes to extent of freezing applications.
Observations:
1) problem disappears when hv_stimer is removed
2) problem disappears when memory backing with huge pages is disabled
3) problem disappears when machine type is downgraded to pc-q35_3.0
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- [Qemu-devel] [Bug 1811533] Re: Unstable Win10 guest with qemu 3.1 + huge pages + hv_stimer,
Damir <=