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Differential D20242

Depessimize arc4rand
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Authored by mjg on May 12 2019, 1:52 AM.
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cem
jmg
markm
delphij
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secteam
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rS347500: random(4): depessimize arc4random
Summary

The function starts with atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED), which at least on x86 always dirties the cacheline. I.e. there is perfectly avoidable line bouncing. While here do minor cleanups.

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rS FreeBSD src repository - subversion
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Event Timeline

mjg created this revision.May 12 2019, 1:52 AM
Herald added a reviewer: jmg. · View Herald TranscriptMay 12 2019, 1:52 AM
Herald added a subscriber: imp. · View Herald Transcript
Harbormaster completed remote builds in B24208: Diff 57326.May 12 2019, 1:52 AM
cem accepted this revision.May 12 2019, 2:24 AM
cem added a reviewer: markm.
This revision is now accepted and ready to land.May 12 2019, 2:24 AM
delphij accepted this revision.May 12 2019, 4:09 AM
delphij added a subscriber: delphij.

Looks reasonable to me.

Closed by commit rS347500: random(4): depessimize arc4random (authored by mjg). · Explain WhyMay 12 2019, 6:33 AM
This revision was automatically updated to reflect the committed changes.

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PathSize
head/
sys/
libkern/
8 lines

Diff 57331

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head/sys/libkern/arc4random.c

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