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

Details

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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R10 FreeBSD src repository
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Event Timeline

markj added reviewers: jhb, gallatin.
jhb added inline comments.
sys/opencrypto/ktls_ocf.c
140

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
sys/opencrypto/ktls_ocf.c
140

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?

sys/opencrypto/ktls_ocf.c
140

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.