diff options
| author | Long Li <longli@microsoft.com> | 2026-03-16 14:07:42 -0700 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2026-03-25 17:36:36 +0000 |
| commit | 7b3b1e5a87b2f5e35c52b5386d7c327be869454f (patch) | |
| tree | 5b615f3d71f67c137289c14806aab46a33620ad6 | |
| parent | c0e296f257671ba10249630fe58026f29e4804d9 (diff) | |
PCI: hv: Set default NUMA node to 0 for devices without affinity info
When hv_pci_assign_numa_node() processes a device that does not have
HV_PCI_DEVICE_FLAG_NUMA_AFFINITY set or has an out-of-range
virtual_numa_node, the device NUMA node is left unset. On x86_64,
the uninitialized default happens to be 0, but on ARM64 it is
NUMA_NO_NODE (-1).
Tests show that when no NUMA information is available from the Hyper-V
host, devices perform best when assigned to node 0. With NUMA_NO_NODE
the kernel may spread work across NUMA nodes, which degrades
performance on Hyper-V, particularly for high-throughput devices like
MANA.
Always set the device NUMA node to 0 before the conditional NUMA
affinity check, so that devices get a performant default when the host
provides no NUMA information, and behavior is consistent on both
x86_64 and ARM64.
Fixes: 999dd956d838 ("PCI: hv: Add support for protocol 1.3 and support PCI_BUS_RELATIONS2")
Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
| -rw-r--r-- | drivers/pci/controller/pci-hyperv.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 2c7a406b4ba8..38a790f642a1 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -2485,6 +2485,14 @@ static void hv_pci_assign_numa_node(struct hv_pcibus_device *hbus) if (!hv_dev) continue; + /* + * If the Hyper-V host doesn't provide a NUMA node for the + * device, default to node 0. With NUMA_NO_NODE the kernel + * may spread work across NUMA nodes, which degrades + * performance on Hyper-V. + */ + set_dev_node(&dev->dev, 0); + if (hv_dev->desc.flags & HV_PCI_DEVICE_FLAG_NUMA_AFFINITY && hv_dev->desc.virtual_numa_node < num_possible_nodes()) /* |