On 11/4/26 16:32, David Vrabel wrote: > When a VM has been assigned a number of PCIe devices behind a common > PCIe switch and the VM intends to use peer-to-peer (P2P) transfers > between the devices, it is useful to be able to more report the > apparent PCIe bandwidth so it reflects the real handwidth of the > underlying hardware. This allows software in the VM (such as NCCL[1]) > to make better decisions about whether to use P2P or not. > > The future QEMU 11.2[1] will support new upstream and downstream port > models that have configurable speed and width properties and extend > the existing root port model to support the same options. > > If supported by QEMU, prefer the new upstream and downstream port > models, and support new attributes to set the speed and width. > > Patch 1 (tests: Update QEMU 11.2.0 x86_64 caps for generic PCIe switch > ports qemu: add capabilities for generic PCIe switch port devices) > should be replaced with a more comprehensive refresh of the QEMU > capabilities, and is only included here so tests continue to pass. > > David > > [1] See QEMU commits 432b3f707a3c (hw/pci-bridge: Make speed and width for > PCIe ports non-experimental) and 73962cc5f06a (hw/pci-bridge: Add > generic PCIe switch upstream and downstream ports). > > David Vrabel (6): > tests: Update QEMU 11.2.0 x86_64 caps for generic PCIe switch ports > qemu: add capabilities for generic PCIe switch port devices > qemu: support generic PCIe switch port models > qemu: add capabilities for pcie-root-port speed and width properties > qemu: add PCIe link speed and width attributes > NEWS: mention generic PCIe switch ports and link speed/width
You earn bonus points for remembering to add NEWS entries :-) > 46 files changed, 1170 insertions(+), 120 deletions(-) > create mode 100644 tests/qemuxmlconfdata/pci-bridge-speed.x86_64-latest.err > create mode 100644 tests/qemuxmlconfdata/pci-bridge-speed.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-root-port-speed-ioh3420.x86_64-latest.err > create mode 100644 tests/qemuxmlconfdata/pcie-root-port-speed-ioh3420.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-root-port-speed-width.x86_64-11.0.0.err > create mode 100644 > tests/qemuxmlconfdata/pcie-root-port-speed-width.x86_64-latest.args > create mode 100644 > tests/qemuxmlconfdata/pcie-root-port-speed-width.x86_64-latest.xml > create mode 100644 tests/qemuxmlconfdata/pcie-root-port-speed-width.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-model-generic.x86_64-11.1.0.err > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-model-generic.x86_64-latest.args > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-model-generic.x86_64-latest.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-model-generic.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-width-xio3130.x86_64-latest.err > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port-width-xio3130.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port.x86_64-11.1.0.args > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-downstream-port.x86_64-11.1.0.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port-model-generic.x86_64-11.1.0.err > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port-model-generic.x86_64-latest.args > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port-model-generic.x86_64-latest.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port-model-generic.xml > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port.x86_64-11.1.0.args > create mode 100644 > tests/qemuxmlconfdata/pcie-switch-upstream-port.x86_64-11.1.0.xml > Reviewed-by: Michal Privoznik <[email protected]> and will merge after Peter refreshes caps. Michal
