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[Qemu-devel] >256 Virtio-net-pci hotplug Devices
From: |
Kinsella, Ray |
Subject: |
[Qemu-devel] >256 Virtio-net-pci hotplug Devices |
Date: |
Mon, 17 Jul 2017 21:50:29 +0000 |
Hi folks,
I am trying to create a VM that supports hot-plugging a large number of
virtio-net-pci device,
up to 1000 devices initially.
>From the docs (see below) and from playing with QEMU, it looks like there are
>two options.
Both with limitations.
PCI Express switch
It looks like using a PCI Express switch hierarchy is not an option due to bus
exhaustion.
Each downstream port creates a separate bus and each downstream port only
supports hot-plugging a single device.
So this gives us a max of 256-ish buses/devices pairs.
PCI Root Ports
The other option is use a flatter hierarchy, with a number of multi-function
PCI Root Ports hanging off 'pcie.0'.
However each 'PCI Root Port' can support hot-plugging a single device.
So this method really becomes a function of how many free address we have on
'pci.0'.
If we make room for say 16 multifunction devices, we get 16*8 ... 128
So ultimately, this will approach will give us a similar to number to using a
switch.
Is there another method?
( pxb-pcie doesn't support hotplug for instance, and only a single pcie domain
is supported qemu )
Thanks,
Ray K
Pcie.txt,
( https://github.com/qemu/qemu/blob/master/docs/pcie.txt )
Q35 preso
( http://wiki.qemu.org/images/4/4e/Q35.pdf )
- [Qemu-devel] >256 Virtio-net-pci hotplug Devices,
Kinsella, Ray <=
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Marcel Apfelbaum, 2017/07/18
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Kinsella, Ray, 2017/07/19
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Marcel Apfelbaum, 2017/07/21
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Kinsella, Ray, 2017/07/21
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Marcel Apfelbaum, 2017/07/23
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Kevin O'Connor, 2017/07/23
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Kinsella, Ray, 2017/07/24
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Marcel Apfelbaum, 2017/07/24
- Re: [Qemu-devel] >256 Virtio-net-pci hotplug Devices, Kinsella, Ray, 2017/07/25