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Differential D60099

arm64: Use only required ordering for coherent dma
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Authored by gallatin on Mon, Sep 28, 5:48 PM.
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F173971938: D60099.diff
Tue, Sep 29, 5:36 PM
F173951812: D60099.id187908.diff
Tue, Sep 29, 2:44 PM
F173950873: D60099.diff
Tue, Sep 29, 2:32 PM
F173858601: D60099.id187908.diff
Mon, Sep 28, 10:53 PM
F173854486: D60099.id187908.diff
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F173854085: D60099.diff
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F173848020: D60099.diff
Mon, Sep 28, 9:16 PM
Subscribers
emaste
imp

Details

Reviewers
andrew
jhb
markj
manu
Summary

Dsb(sy) carries a huge amount of overhead.. This seems like overkill for
coherent DMA. Replace it with dmb(oshld)/dmb(oshst)

This saves about 1.5% CPU on my tiny N1 setup serving 80Gb/s of Netflix traffic.

Note this depends on D60098 to apply.

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Event Timeline

gallatin created this revision.Mon, Sep 28, 5:48 PM
Herald added a reviewer: manu. · View Herald TranscriptMon, Sep 28, 5:48 PM
Herald added subscribers: emaste, imp. · View Herald Transcript
gallatin requested review of this revision.Mon, Sep 28, 5:48 PM
andrew added a comment.Tue, Sep 29, 1:58 PM

I think the dmb instructions are correct even for the non-coherent case

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FreeBSD/
sys/
arm64/
arm64/
11 lines

Diff 187908

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FreeBSD/sys/arm64/arm64/busdma_bounce.c

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