Re: [Qemu-devel] [PATCH 1/5] virtio-net: Make tx_timer timeout configurable

[Chris Wright <chrisw@sous-sol.org>]

* Alex Williamson (alex.williamson@redhat.com) wrote:
> On Tue, 2010-08-31 at 11:00 -0700, Chris Wright wrote:
> > * Alex Williamson (alex.williamson@redhat.com) wrote:
> > > diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> > > index 075f72d..9ef29f0 100644
> > > --- a/hw/virtio-net.c
> > > +++ b/hw/virtio-net.c
> > > @@ -36,6 +36,7 @@ typedef struct VirtIONet
> > >      VirtQueue *ctrl_vq;
> > >      NICState *nic;
> > >      QEMUTimer *tx_timer;
> > > +    uint32_t tx_timeout;
> > >      int tx_timer_active;
> > >      uint32_t has_vnet_hdr;
> > >      uint8_t has_ufo;
> > > @@ -702,7 +703,7 @@ static void virtio_net_handle_tx(VirtIODevice *vdev, VirtQueue *vq)
> > >          virtio_net_flush_tx(n, vq);
> > >      } else {
> > >          qemu_mod_timer(n->tx_timer,
> > > -                       qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
> > > +                       qemu_get_clock(vm_clock) + n->tx_timeout);
> > >          n->tx_timer_active = 1;
> > >          virtio_queue_set_notification(vq, 0);
> > >      }
> > > @@ -842,7 +843,7 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
> > >  
> > >      if (n->tx_timer_active) {
> > >          qemu_mod_timer(n->tx_timer,
> > > -                       qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
> > > +                       qemu_get_clock(vm_clock) + n->tx_timeout);
> > 
> > I think I'm missing where this is stored?  Looks like migration
> > would revert a changed tx_timeout back to 150us.
> 
> It's not stored, it can be instantiated on the migration target any way
> you please and we can migrate between different values or even different
> TX mitigation strategies.  If a non-default value is used on the source
> and you want to maintain the same behavior, the target needs to be
> started the same way.

heh, IOW, I did miss how it's stored...on cmdline ;)

thanks,
-chris