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Differential D4853

hyperv/hn: Avoid mbuf cluster allocation on reception path, if the packet is small
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Authored by sepherosa_gmail.com on Jan 11 2016, 5:38 AM.
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kmacy
howard0su_gmail.com
honzhan_microsoft.com
decui_microsoft.com
delphij
royger
adrian
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network
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rS293721: hyperv/hn: Avoid mbuf cluster allocation, if the packet is small.
Summary

This gives me ~200Mbps improvement, when running iperf3 sending test w/ 16 connections.

While I'm here, nuke the unnecessary pkthdr.csum_flags zeroing out.

Sponsored by: Microsoft OSTC

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rS FreeBSD src repository - subversion
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sepherosa_gmail.com updated this revision to Diff 12102.Jan 11 2016, 5:38 AM
sepherosa_gmail.com retitled this revision from to hyperv/hn: Avoid mbuf cluster allocation on reception path, if the packet is small.
sepherosa_gmail.com updated this object.
sepherosa_gmail.com edited the test plan for this revision. (Show Details)
sepherosa_gmail.com added reviewers: network, kmacy, adrian, delphij, royger, decui_microsoft.com, honzhan_microsoft.com, howard0su_gmail.com.
sepherosa_gmail.com added a subscriber: freebsd-net-list.

If no objection comes, this will be committed this week.

adrian accepted this revision.Jan 11 2016, 6:48 AM
adrian edited edge metadata.

You should explain more why the change improves performance more dramatically when you commit. other than that, it's fine!

This revision is now accepted and ready to land.Jan 11 2016, 6:48 AM
sepherosa_gmail.com added a comment.Jan 11 2016, 6:49 AM
In D4853#103167, @adrian wrote:

You should explain more why the change improves performance more dramatically when you commit. other than that, it's fine!

Sure, thanks.

jtl added a subscriber: jtl.Jan 12 2016, 1:50 AM
jtl added inline comments.
sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c
475 ↗(On Diff #12102)

Is there a reason this is read/write?

1036 ↗(On Diff #12102)

Do you need an atomic operation here to guarantee accurate statistics? (And, even if you do, is it that important?)

Closed by commit rS293721: hyperv/hn: Avoid mbuf cluster allocation, if the packet is small. (authored by sephe). · Explain WhyJan 12 2016, 1:51 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

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sys/
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head/sys/dev/hyperv/netvsc/hv_net_vsc.h

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head/sys/dev/hyperv/netvsc/hv_netvsc_drv_freebsd.c

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