From: Alex Williamson <alex.williamson@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>,
Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
Zihan Yang <whois.zihan.yang@gmail.com>,
qemu-devel@nongnu.org, Igor Mammedov <imammedo@redhat.com>,
Eric Auger <eauger@redhat.com>, Drew Jones <drjones@redhat.com>,
Wei Huang <wei@redhat.com>
Subject: Re: [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges
Date: Tue, 22 May 2018 15:36:59 -0600 [thread overview]
Message-ID: <20180522153659.2e33fbe0@w520.home> (raw)
In-Reply-To: <20180522234410-mutt-send-email-mst@kernel.org>
On Tue, 22 May 2018 23:58:30 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> It's not hard to think of a use-case where >256 devices
> are helpful, for example a nested virt scenario where
> each device is passed on to a different nested guest.
>
> But I think the main feature this is needed for is numa modeling.
> Guests seem to assume a numa node per PCI root, ergo we need more PCI
> roots.
But even if we have NUMA affinity per PCI host bridge, a PCI host
bridge does not necessarily imply a new PCIe domain. Nearly any Intel
multi-socket system proves this. Don't get me wrong, I'd like to see
PCIe domain support and I'm surprised edk2 is so far from supporting
it, but other than >256 hotpluggable slots, I'm having trouble coming
up with use cases. Maybe hotpluggable PCI root hierarchies are easier
with separate domains? Thanks,
Alex
next prev parent reply other threads:[~2018-05-22 21:37 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-20 7:28 [Qemu-devel] [RFC 0/3] pci_expander_brdige: Put pxb host bridge into separate pci domain Zihan Yang
2018-05-20 7:28 ` [Qemu-devel] [RFC 1/3] pci_expander_bridge: reserve enough mcfg space for pxb host Zihan Yang
2018-05-21 11:03 ` Marcel Apfelbaum
2018-05-22 5:59 ` Zihan Yang
2018-05-22 18:47 ` Marcel Apfelbaum
2018-05-20 7:28 ` [Qemu-devel] [RFC 2/3] pci: Link pci_host_bridges with QTAILQ Zihan Yang
2018-05-21 11:05 ` Marcel Apfelbaum
2018-05-22 5:59 ` Zihan Yang
2018-05-22 18:39 ` Marcel Apfelbaum
2018-05-20 7:28 ` [Qemu-devel] [RFC 3/3] acpi-build: allocate mcfg for multiple host bridges Zihan Yang
2018-05-21 11:53 ` Marcel Apfelbaum
2018-05-22 6:03 ` Zihan Yang
2018-05-22 18:43 ` Marcel Apfelbaum
2018-05-22 9:52 ` Laszlo Ersek
2018-05-22 19:01 ` Marcel Apfelbaum
2018-05-22 19:51 ` Laszlo Ersek
2018-05-22 20:58 ` Michael S. Tsirkin
2018-05-22 21:36 ` Alex Williamson [this message]
2018-05-22 21:44 ` Michael S. Tsirkin
2018-05-22 21:47 ` Alex Williamson
2018-05-22 22:00 ` Laszlo Ersek
2018-05-22 23:38 ` Michael S. Tsirkin
2018-05-23 4:28 ` Alex Williamson
2018-05-23 14:25 ` Michael S. Tsirkin
2018-05-23 14:57 ` Alex Williamson
2018-05-23 15:01 ` Michael S. Tsirkin
2018-05-23 16:50 ` Marcel Apfelbaum
2018-05-22 21:17 ` Alex Williamson
2018-05-22 21:22 ` Michael S. Tsirkin
2018-05-22 21:58 ` Laszlo Ersek
2018-05-22 21:50 ` Laszlo Ersek
2018-05-23 17:00 ` Marcel Apfelbaum
2018-05-22 22:42 ` Laszlo Ersek
2018-05-22 23:40 ` Michael S. Tsirkin
2018-05-23 7:32 ` Laszlo Ersek
2018-05-23 11:11 ` Zihan Yang
2018-05-23 12:28 ` Laszlo Ersek
2018-05-23 17:23 ` Marcel Apfelbaum
2018-05-24 9:57 ` Zihan Yang
2018-05-23 17:33 ` Marcel Apfelbaum
2018-05-24 10:00 ` Zihan Yang
2018-05-23 17:11 ` Marcel Apfelbaum
2018-05-23 17:25 ` Laszlo Ersek
2018-05-28 11:02 ` Laszlo Ersek
2018-05-21 15:23 ` [Qemu-devel] [RFC 0/3] pci_expander_brdige: Put pxb host bridge into separate pci domain Marcel Apfelbaum
2018-05-22 6:04 ` Zihan Yang
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