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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Reviewers

kmacy
howard0su_gmail.com
honzhan_microsoft.com
decui_microsoft.com
delphij
royger
adrian

Group Reviewers

network

Commits

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.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Event Timeline

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

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

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?)