Increasing Virtio driver TX scatter gather segments (VTNET_MIN_TX_SEGS) to support JUMBO MTU frames.
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Authored by lohithbsd_gmail.com on Dec 15 2016, 5:14 AM.

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bryanv
hiren
adrian

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rS321679: vtnet: Support jumbo frames without TSO/GSO

Summary

Currently in Virtio driver without TSO/GSO features enabled, the max scatter gather segments for the TX path can be 4, which limits the support for 9K JUMBO frames. 9K JUMBO frames results in more than 4 scatter gather segments and virtio driver fails to send the frame down to host OS. With TSO/GSO feature enabled max scatter gather segments can be 64, then 9K JUMBO frames are fine, this is making virtio driver to support JUMBO frames only with TSO/GSO. Increasing the VTNET_MIN_TX_SEGS which is the case for non TSO/GSO to 32 to support upto 64K JUMBO frames to Host.

Test Plan

Verified the 64K JUMBO frames transmission between FreeBSD guest OS and Yocto Linux Host OS.

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rS FreeBSD src repository - subversion

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lohithbsd_gmail.com updated this revision to Diff 22940.Dec 15 2016, 5:14 AM

lohithbsd_gmail.com retitled this revision from to Increasing Virtio driver TX scatter gather segments (VTNET_MIN_TX_SEGS) to support JUMBO MTU frames..

lohithbsd_gmail.com updated this object.

lohithbsd_gmail.com edited the test plan for this revision. (Show Details)

lohithbsd_gmail.com added reviewers: bryanv, adrian, hiren.

Herald added a subscriber: imp. · View Herald TranscriptDec 15 2016, 5:14 AM

looks good! do you need this committed?

This revision is now accepted and ready to land.Dec 30 2016, 2:48 PM

In D8803#185745, @adrian wrote:

looks good! do you need this committed?

Hi, I've got a few concerns so please hold off for now. Thanks.

In D8803#185745, @adrian wrote:

looks good! do you need this committed?

Thanks a lot Adrian. I am waiting for Bryan's comments. Yes, need your help in committing.

Cheers,
Lohith

@bryanv do you have time to look at this now?

Closed by commit rS321679: vtnet: Support jumbo frames without TSO/GSO (authored by kp). · Explain WhyJul 29 2017, 9:23 AM

This revision was automatically updated to reflect the committed changes.

Revision Contents
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Path

Size

head/

sys/

dev/

virtio/

network/

if_vtnetvar.h

2 lines

Diff 31331

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head/sys/dev/virtio/network/if_vtnetvar.h

Increasing Virtio driver TX scatter gather segments (VTNET_MIN_TX_SEGS) to support JUMBO MTU frames.ClosedPublicActions