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path: root/internal/cryptocore/randprefetch.go
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2017-06-11cryptocore: prefetch nonces in the backgroundJakob Unterwurzacher
Spawn a worker goroutine that reads the next 512-byte block while the current one is being drained. This should help reduce waiting times when /dev/urandom is very slow (like on Linux 3.16 kernels).
2017-06-09cryptocore: prefetch nonces in 512-byte blocksJakob Unterwurzacher
On my machine, reading 512-byte blocks from /dev/urandom (same via getentropy syscall) is a lot faster in terms of throughput: Blocksize Throughput 16 28.18 MB/s 512 83.75 MB/s For a single-threaded streaming write, this drops the CPU usage of nonceGenerator.Get to almost 1/3: flat flat% sum% cum cum% Before 0 0% 95.08% 0.35s 2.92% github.com/rfjakob/gocryptfs/internal/cryptocore.(*nonceGenerator).Get After 0.01s 0.092% 92.34% 0.13s 1.20% github.com/rfjakob/gocryptfs/internal/cryptocore.(*nonceGenerator).Get This change makes the nonce reading single-threaded, which may hurt massively-parallel writes.