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pf: add pf_bcmp_state_key
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Authored by mjg on Nov 26 2021, 3:09 PM.

Details

Summary

The comparison size of 40 bytes is known at compilation time but clang refuses to optimize it, thus hand-roll a short variant.

Benchmarked on a kernel with other changes on top of it. Interestingly it fails to provide a speed up, but instead it shifts CPU time elsewhere.

before: https://people.freebsd.org/~mjg/pf_nohashrow.svg
after: https://people.freebsd.org/~mjg/pf_nohashrow_custom_bcmp.svg

You can see time in netisr_dispatch -> ip_input -> ip_tryforward drop from 12.19 to 10.40 of the total.

Diff Detail

Repository
R10 FreeBSD src repository
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Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

mjg requested review of this revision.Nov 26 2021, 3:09 PM
sys/netpfil/pf/pf.c
430

s1ptr (and s2ptr) is not declared anywhere. Do you mean var1 = k1[0]?

432

Can't we do if (k1[0] != k2[0])?

mjg marked 2 inline comments as done.Nov 27 2021, 4:24 PM
mjg added inline comments.
sys/netpfil/pf/pf.c
430

i somehow upload the older version

There's one more in sys/netpfil/pf/pf_lb.c that could also use pf_bcmp_state_key() (in pf_get_translation()).

This revision is now accepted and ready to land.Nov 27 2021, 5:07 PM
This revision was automatically updated to reflect the committed changes.
mjg marked an inline comment as done.