ktls: Avoid wakeups and locking for synchronous callbacks
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Authored by markj on Jan 16 2021, 6:59 PM.

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jmg
jhb
gallatin

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rGdb6b56441e3a: ktls: Avoid wakeups and locking for synchronous callbacks

Summary

The KTLS crypto callback always locks the session to deliver a wakeup.
But if we're handling the operation synchronously this is wasted effort.
On an Ampere server this results in a large amount of sleepqueue lock
contention. Use CRYPTO_SESS_SYNC() to determine whether the operation
will be completed asynchronously or not, and select a callback
appropriately.

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rG FreeBSD src repository

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Event Timeline

markj created this revision.Jan 16 2021, 6:59 PM

Herald added a reviewer: jmg. · View Herald TranscriptJan 16 2021, 6:59 PM

Herald added a subscriber: imp. · View Herald Transcript

Harbormaster completed remote builds in B36274: Diff 82379.Jan 16 2021, 6:59 PM

markj requested review of this revision.Jan 16 2021, 6:59 PM

markj added a parent revision: D28194: opencrypto: Introduce crypto_dispatch_async().

markj edited the summary of this revision. (Show Details)Jan 16 2021, 7:00 PM

markj added reviewers: jhb, gallatin.

jhb accepted this revision.Jan 19 2021, 7:48 PM

jhb added inline comments.

sys/opencrypto/ktls_ocf.c
141	These two statements can be moved up out of the loop.

This revision is now accepted and ready to land.Jan 19 2021, 7:48 PM

markj added inline comments.Jan 19 2021, 7:52 PM

sys/opencrypto/ktls_ocf.c
141	I had written it that way originally, but I noticed that we handle EAGAIN (i.e., the crypto driver changed) by looping, in which case we should re-evaluate the flag. Does that not make sense for some reason?

jhb added inline comments.Jan 21 2021, 6:24 PM

sys/opencrypto/ktls_ocf.c
141	Oh, humm, ok. I think long term I want crypto_dispatch() to return `EINPROGRESS` when it doesn't complete the request synchronously, but this is fine for now.