Jason Wang
2023-Sep-25 02:29 UTC
[PATCH net 5/6] virtio-net: fix the vq coalescing setting for vq resize
On Fri, Sep 22, 2023 at 3:58?PM Heng Qi <hengqi at linux.alibaba.com> wrote:> > > > ? 2023/9/22 ??3:32, Jason Wang ??: > > On Fri, Sep 22, 2023 at 1:02?PM Heng Qi <hengqi at linux.alibaba.com> wrote: > >> > >> > >> ? 2023/9/22 ??12:29, Jason Wang ??: > >>> On Tue, Sep 19, 2023 at 3:49?PM Heng Qi <hengqi at linux.alibaba.com> wrote: > >>>> According to the definition of virtqueue coalescing spec[1]: > >>>> > >>>> Upon disabling and re-enabling a transmit virtqueue, the device MUST set > >>>> the coalescing parameters of the virtqueue to those configured through the > >>>> VIRTIO_NET_CTRL_NOTF_COAL_TX_SET command, or, if the driver did not set > >>>> any TX coalescing parameters, to 0. > >>>> > >>>> Upon disabling and re-enabling a receive virtqueue, the device MUST set > >>>> the coalescing parameters of the virtqueue to those configured through the > >>>> VIRTIO_NET_CTRL_NOTF_COAL_RX_SET command, or, if the driver did not set > >>>> any RX coalescing parameters, to 0. > >>>> > >>>> We need to add this setting for vq resize (ethtool -G) where vq_reset happens. > >>>> > >>>> [1] https://lists.oasis-open.org/archives/virtio-dev/202303/msg00415.html > >>>> > >>>> Fixes: 394bd87764b6 ("virtio_net: support per queue interrupt coalesce command") > >>> I'm not sure this is a real fix as spec allows it to go zero? > >> The spec says that if the user has configured interrupt coalescing > >> parameters, > >> parameters need to be restored after vq_reset, otherwise set to 0. > >> vi->intr_coal_tx and vi->intr_coal_rx always save the newest global > >> parameters, > >> regardless of whether the command is sent or not. So I think we need > >> this patch > >> it complies with the specification requirements. > > How can we make sure the old coalescing parameters still make sense > > for the new ring size? > > I'm not sure, ringsize has a wider range of changes. Maybe we should > only keep coalescing > parameters in cases where only vq_reset occurs (no ring size change > involved)?Probably but do we actually have a user other than resize now? Thanks> > Thanks! > > > > > Thanks > > > >> Thanks! > >> > >>> Thanks >