From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when
 available
Date: Tue, 19 Dec 2017 09:55:48 -0800
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Cc: "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        alexander.duyck@gmail.com,
        "Brandeburg, Jesse" <jesse.brandeburg@intel.com>
To: "Samudrala, Sridhar" <sridhar.samudrala@intel.com>
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On Tue, 19 Dec 2017 09:41:39 -0800
"Samudrala, Sridhar" <sridhar.samudrala@intel.com> wrote:

> On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:
> > I'll need to look at this more, in particular the feature
> > bit is missing here. For now one question:
> >
> > On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote: =20
> >> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
> >>    */
> >>   DECLARE_EWMA(pkt_len, 0, 64)
> >>  =20
> >> +#define VF_TAKEOVER_INT	(HZ / 10)
> >> +
> >>   #define VIRTNET_DRIVER_VERSION "1.0.0"
> >>  =20
> >>   static const unsigned long guest_offloads[] =3D { =20
> > Why is this delay necessary? And why by 100ms? =20
>=20
> This is based on netvsc implementation and here is the commit that
> added this delay.=C2=A0 Not sure if this needs to be 100ms.
>=20
> commit 6123c66854c174e4982f98195100c1d990f9e5e6
> Author: stephen hemminger <stephen@networkplumber.org>
> Date:=C2=A0=C2=A0 Wed Aug 9 17:46:03 2017 -0700
>=20
>  =C2=A0=C2=A0=C2=A0 netvsc: delay setup of VF device
>=20
>  =C2=A0=C2=A0=C2=A0 When VF device is discovered, delay bring it automati=
cally up in
>  =C2=A0=C2=A0=C2=A0 order to allow userspace to some simple changes (like=
 renaming).
>=20
>=20
>=20

could be 10ms, just enough to let udev do its renaming