Yuxue Liu 4d685629b7 vp_vdpa: don't allocate unused msix vectors ... When there is a ctlq and it doesn't require interrupt callbacks,the original method of calculating vectors wastes hardware msi or msix resources as well as system IRQ resources. When conducting performance testing using testpmd in the guest os, it was found that the performance was lower compared to directly using vfio-pci to passthrough the device In scenarios where the virtio device in the guest os does not utilize interrupts, the vdpa driver still configures the hardware's msix vector. Therefore, the hardware still sends interrupts to the host os. Because of this unnecessary action by the hardware, hardware performance decreases, and it also affects the performance of the host os. Before modification:(interrupt mode) 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 33: 0 0 0 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-2 35: 0 0 0 0 PCI-MSI 32771-edge vp-vdpa[0000:00:02.0]-config After modification:(interrupt mode) 32: 0 0 1 7 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 33: 36 0 3 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-config Before modification:(virtio pmd mode for guest os) 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-0 33: 0 0 0 0 PCI-MSI 32769-edge vp-vdpa[0000:00:02.0]-1 34: 0 0 0 0 PCI-MSI 32770-edge vp-vdpa[0000:00:02.0]-2 35: 0 0 0 0 PCI-MSI 32771-edge vp-vdpa[0000:00:02.0]-config After modification:(virtio pmd mode for guest os) 32: 0 0 0 0 PCI-MSI 32768-edge vp-vdpa[0000:00:02.0]-config To verify the use of the virtio PMD mode in the guest operating system, the following patch needs to be applied to QEMU: https://lore.kernel.org/all/20240408073311.2049-1-yuxue.liu@jaguarmicro.com Signed-off-by: Yuxue Liu <yuxue.liu@jaguarmicro.com> Acked-by: Jason Wang <jasowang@redhat.com> Reviewed-by: Heng Qi <hengqi@linux.alibaba.com> Message-Id: <20240410033020.1310-1-yuxue.liu@jaguarmicro.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>		2024-05-22 08:31:18 -04:00
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Makefile
vp_vdpa.c	vp_vdpa: don't allocate unused msix vectors	2024-05-22 08:31:18 -04:00