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Mon, 23 Jun 2008

POHMELFS client got initial part of multithreaded crypto/checksum processing.

So far it only includes encryption and hash calculation for outgoing transactions. System has (mount option) number of threads per superblock, which are responsible for encryption/hashing (each thread has own crypto structure, so there are no additional allocations in the fast path, although I think they would not harm performance since should be small enough fraction on top of crypto processing overhead) and subsequent data sending, so original caller (like writeback/readahead code) will not block if there are ready threads, otherwise it will wait until some thread finishes its current crypto work.

I decided to implement kind of continuation for such transactions, when network sending code (which is supposed to be started after crypto processing) will be invoked from those threads, which performed crypto operations, and not returning back to originall caller context. For massively multiqueue NICs that should be a benefit, but so far I did not test its performance.
Next step is receiving crypto support and userspace changes.

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