Don't deref an mbuf ext_pgs pointer in tcp_m_copym() unless we need to
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Authored by gallatin on Mar 7 2020, 10:56 PM.

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melifaro

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rrs
jhb
jtl

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transport

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rS359016: Avoid a cache miss accessing an mbuf ext_pgs pointer when doing SW kTLS.

Summary

Avoid a cache miss accessing an mbuf ext_pgs pointer when not doing hardware TLS.

For a Netflix 90Gb/s 100% TLS software TLS workload, this reduces the CPI of tcp_m_copym() from ~3.5 to ~2.5 as reported by vtune.

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rS FreeBSD src repository - subversion

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Event Timeline

gallatin created this revision.Mar 7 2020, 10:56 PM

Herald added a reviewer: transport. · View Herald TranscriptMar 7 2020, 10:56 PM

Herald added subscribers: melifaro, imp. · View Herald Transcript

Harbormaster completed remote builds in B29843: Diff 69302.Mar 7 2020, 10:57 PM

rrs accepted this revision.Mar 8 2020, 4:14 PM

This revision is now accepted and ready to land.Mar 8 2020, 4:14 PM

jtl accepted this revision.Mar 9 2020, 4:25 PM

Closed by commit rS359016: Avoid a cache miss accessing an mbuf ext_pgs pointer when doing SW kTLS. (authored by gallatin). · Explain WhyMar 16 2020, 2:03 PM

This revision was automatically updated to reflect the committed changes.

gallatin added a commit: rS359016: Avoid a cache miss accessing an mbuf ext_pgs pointer when doing SW kTLS..

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head/

sys/

netinet/

tcp_output.c

2 lines

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head/sys/netinet/tcp_output.c

Don't deref an mbuf ext_pgs pointer in tcp_m_copym() unless we need toClosedPublicActions