On Tue, Aug 30, 2022 at 02:04:55PM -0700, Si-Wei Liu wrote: > > > On 8/30/2022 12:58 PM, Michael S. Tsirkin wrote: > > On Tue, Aug 30, 2022 at 06:22:31AM +0000, Eli Cohen wrote: > > > > > > Hi, > > > > > > > > > I have been experimenting with different queue sizes with mlx5_vdpa and noticed > > > that queue size can affect performance. > > > > > > I would like to propose an extension to vdpa tool to allow to specify the queue > > > size. Valid values will conform to the max of 32768 specified by the spec. > > > > > > > > > “vdpa mgmtdev show” will have another line specifying the valid range for a > > > management device which could be narrower than the spec allows. This range will > > > be valid for data queues only (not for control VQ). > > > > > > Another line will display the default queue size > > > > > > > > > Example: > > > > > > $ vdpa mgmtdev show > > > > > > auxiliary/mlx5_core.sf.6: > > > > > > supported_classes net > > > > > > max_supported_vqs 65 > > > > > > dev_features CSUM GUEST_CSUM MTU HOST_TSO4 HOST_TSO6 STATUS CTRL_VQ CTRL_VLAN > > > MQ CTRL_MAC_ADDR VERSION_1 ACCESS_PLATFORM > > > > > > data queue range 256-4096 > > > > > > default queue size 256 > > > > > > > > > When you create the vdpa device you can specify the requested value: > > > > > > $ vdpa dev add name vdpa-a mgmtdev auxiliary/mlx5_core.sf.6 max_vqp 1 mtu 9000 > > > queue_size 1024 > > > > > > > A follow up question: isn't it enough to control the size > > from qemu? do we need ability to control it at the kernel level? > > > Right, I think today we can optionally control the queue size from qemu via > rx_queue_size or tx_queue_size, but it has a limit of 1024 (btw why it has > such limit, which is relatively lower in my opinion). I think what was > missing for QEMU is to query the max number of queue size that the hardware > can support from the backend. > > -Siwei > okay sure. my question is how important is it to control it in the kernel? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
