Date: Mon, 10 Oct 2016 18:17:54 -0700 From: Lohith Bellad <lohithbsd@gmail.com> To: freebsd-net@freebsd.org, bryanv@FreeBSD.org Subject: Problem with Virtio using JUMBO frame config. Message-ID: <F90A6D7D-D013-4936-A7FB-39B5C98CC739@gmail.com>
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Hi All,
I want to use Virtio with JUMBO frame support without TSOv4, TSOv6 and =
GSO.
Looks like without TSOv4, TSOv6 and GSO. The max number of segments =
allowed for scatter gather operations is 4.=20
But, if TSOv4, TSOv6 or GSO feature is enabled, max segments for scatter =
gather is set to 64.
sys/dev/virtio/network/if_vtnet.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D
if (virtio_with_feature(dev, VIRTIO_NET_F_GSO) ||
virtio_with_feature(dev, VIRTIO_NET_F_HOST_TSO4) ||
virtio_with_feature(dev, VIRTIO_NET_F_HOST_TSO6))
sc->vtnet_tx_nsegs =3D VTNET_MAX_TX_SEGS; <=3D=3D 64
else
sc->vtnet_tx_nsegs =3D VTNET_MIN_TX_SEGS; <=3D=3D 4
In my case since I don=E2=80=99t have TSOv4, TSOv6 or GSO enabled, so =
max segments is 4.
And if I try to send PING echo with size 18000 or more (results into 3 =
frames), driver is failing to send it. PING with size less than 15000 =
works always.
Using dtrace and vtnet sysctls found that, in my case scatter gather =
segments are more than 4 and thats why EFBIG error is returned by =
sglist_append_mbuf().
Also, vtnet defrag failed stats are increasing,
dev.vtnet.4.tx_defragged: 111443
dev.vtnet.4.tx_defrag_failed: 7917
These changes were done in following commit
https://svnweb.freebsd.org/base?view=3Drevision&revision=3D261394
So, is JUMBO frame support allowed only with TSO support or am I missing =
something.
Any help is appreciated.
Thanks,
Lohith
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