sriovtotalvfs

sriovtotalvfs is a kernel parameter in Linux that controls the maximum number of Virtual Functions (VFs) that can be created for a given SR-IOV (Single Root I/O Virtualization) device. SR-IOV is a hardware technology that allows a single PCI device to appear as multiple separate devices to the operating system or hypervisor. This is achieved by creating Virtual Functions (VFs) which are lightweight instances of the physical device, each with its own set of resources and a unique MAC address.

The sriovtotalvfs parameter is typically used when configuring SR-IOV devices, particularly network interface cards (NICs). By default, a device might be configured to support a certain number of VFs. However, the sriovtotalvfs parameter allows administrators to explicitly set a different maximum number of VFs. This can be useful for optimizing resource allocation, managing the number of virtual machines that can directly access the hardware, or in scenarios where the hardware's default configuration is not ideal for the specific workload.

Setting the sriovtotalvfs parameter is usually done via the sysfs filesystem. For example, to set the maximum number of VFs for a specific device, one might write a value to a file located at /sys/bus/pci/devices/<device_id>/sriov_totalvfs. It is important to note that the actual number of VFs that can be created is also limited by the physical capabilities of the SR-IOV device itself and the underlying hardware architecture. Changing this parameter might require a device reset or re-initialization for the changes to take effect.