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Re: [Qemu-devel] Flatview rendering scalability issue
From: |
Sergio Lopez |
Subject: |
Re: [Qemu-devel] Flatview rendering scalability issue |
Date: |
Mon, 11 Mar 2019 15:35:11 +0100 |
User-agent: |
mu4e 1.0; emacs 26.1 |
Paolo Bonzini writes:
> On 11/03/19 14:48, Sergio Lopez wrote:
>>> The initialization is O(n^2) because the guest initializes one device at
>>> a time, so you rebuild the FlatView first with 0 devices, then 1, then
>>> 2, etc. This is very hard to fix, if at all possible.
>>>
>>> However, each FlatView creation should be O(n) where n is the number of
>>> devices currently configured. Please check with "info mtree -f" that
>>> you only have a fixed number of FlatViews. Old versions had one per device.
>> I'm seeing 9 FVs with 1 PCI, and 119 with 100 PCIs.
>
> With
>
> $ eval qemu-system-x86_64 -M q35 \
> -device\ e1000,id=n{1,2,3,4,5,6,7,8}{1,2,3}
>
> I only see 4 flat views ("system", "io", "memory", "(none)").
>
> Probably you are using intel-iommu? Peter, it should be possible to
> reorganize the VT-d memory regions like this:
You're right, the number of FVs goes down drastically after removing
intel-iommu, and the slowness during Guest PCI initialization disappears
with it.
Thanks,
Sergio.
- [Qemu-devel] Flatview rendering scalability issue, Sergio Lopez, 2019/03/11
- Re: [Qemu-devel] Flatview rendering scalability issue, Paolo Bonzini, 2019/03/11
- Re: [Qemu-devel] Flatview rendering scalability issue, Sergio Lopez, 2019/03/11
- Re: [Qemu-devel] Flatview rendering scalability issue, Paolo Bonzini, 2019/03/11
- Re: [Qemu-devel] Flatview rendering scalability issue,
Sergio Lopez <=
- Re: [Qemu-devel] Flatview rendering scalability issue, Peter Xu, 2019/03/11
- Re: [Qemu-devel] Flatview rendering scalability issue, Paolo Bonzini, 2019/03/12
- Re: [Qemu-devel] Flatview rendering scalability issue, Peter Xu, 2019/03/12
- Re: [Qemu-devel] Flatview rendering scalability issue, Paolo Bonzini, 2019/03/12
- Re: [Qemu-devel] Flatview rendering scalability issue, Peter Xu, 2019/03/12