On Mon, Jun 10, 2024 at 10:27:37PM +0200, Paul Menzel wrote:
> Am 10.06.24 um 21:42 schrieb Bjorn Helgaas:
> > On Sun, Jun 09, 2024 at 10:31:05AM +0200, Paul Menzel wrote:
> > > On the servers below Linux warns:
> > >
> > > Unknown NUMA node; performance will be reduced
> >
> > This warning was added by ad5086108b9f ("PCI: Warn if no host bridge
> > NUMA node info"), which appeared in v5.5, so I assume this isn't new.
> >
> > That commit log says:
> >
> > In pci_call_probe(), we try to run driver probe functions on the node where
> > the device is attached. If we don't know which node the device is attached
> > to, the driver will likely run on the wrong node. This will still work,
> > but performance will not be as good as it could be.
> >
> > On NUMA systems, warn if we don't know which node a PCI host bridge is
> > attached to. This is likely an indication that ACPI didn't supply a _PXM
> > method or the DT didn't supply a "numa-node-id" property.
> >
> > I assume these are all ACPI systems, so likely missing _PXM. An
> > acpidump could confirm this.
>
> I created an issue in the Linux Kernel Bugzilla [1] and attached the output
> of `acpidump` on a Dell PowerEdge T630 there. The DSDT contains:
>
> Device (PCI1)
> {
> […]
> Method (_PXM, 0, NotSerialized) // _PXM: Device Proximity
> {
> If ((CLOD == 0x00))
> {
> Return (0x01)
> }
> Else
> {
> Return (0x02)
> }
> }
> […]
> }
This machine (the T630, from your first message) has several PCI host
bridges:
ACPI: PCI Root Bridge [UNC1] (domain 0000 [bus ff])
pci_bus 0000:ff: root bus resource [bus ff]
ACPI: PCI Root Bridge [UNC0] (domain 0000 [bus 7f])
pci_bus 0000:7f: root bus resource [bus 7f]
ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-7e])
pci_bus 0000:00: root bus resource [io 0x0000-0x03bb window]
pci_bus 0000:00: root bus resource [io 0x03bc-0x03df window]
pci_bus 0000:00: root bus resource [io 0x03e0-0x0cf7 window]
pci_bus 0000:00: root bus resource [io 0x1000-0x7fff window]
pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window]
pci_bus 0000:00: root bus resource [mem 0x90000000-0xc7ffbfff window]
pci_bus 0000:00: root bus resource [mem 0x38000000000-0x3bfffffffff window]
pci_bus 0000:00: root bus resource [bus 00-7e]
ACPI: PCI Root Bridge [PCI1] (domain 0000 [bus 80-fe])
pci_bus 0000:80: root bus resource [io 0x8000-0xffff window]
pci_bus 0000:80: root bus resource [mem 0xc8000000-0xfbffbfff window]
pci_bus 0000:80: root bus resource [mem 0x3c000000000-0x3ffffffffff window]
pci_bus 0000:80: root bus resource [bus 80-fe]
PCI0 and PCI1 lead to all your normal PCI devices, they both
implement _PXM, and they have all the usual apertures for PCI I/O and
MMIO space where device BARs live.
UNC0 and UNC1 lead to these special chipset devices, they don't
implement _PXM, and they don't have any resources except the bus
number. The devices on bus 7f and ff can only be used via config
space accesses, and I have no idea what they are used for.
> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=218951
