libp2p-noise handshake performance

[twoeths]

Investigate why libp2p-noise handshake takes > 7% of cpu time

0522_contabo_20_subscribe_all_subnets.cpuprofile.zip

[dapplion]

• @tuyennhv see Use faster Ed25519 impl for gossip crypto #3465

[twoeths]

this function takes time

[twoeths]

@dapplion the hot path is at chaCha20Poly1305 encrypt/decrypt, not at x25519.js

[wemeetagain]

looks like nonce and the DataView can be created once in the constructor and overwritten and returned each time.
not sure if its worth it given chachapoly1305 is the hot path.
Take a look at the last comment in #3465 where someone swaps in a native implementation of chachapoly1305 with our noise implementation.

[twoeths]

nonceToBytes() takes > 1% of cpu time, it's all most the time we call as-sha256.digest() or uncompress gossip messages so I think it's worth to improve it if we can

right now we maintain an uint, call nonceToBytes() and increase it every time we encrypt/decrypt. We can instead maintain Uint8Array, no need to call nonceToBytes() and do the increasement manually with Uint8Array. Need to write a performance test to see if it's better

[twoeths]

looks like nonce and the DataView can be created once in the constructor and overwritten and returned each time.
not sure if its worth it given chachapoly1305 is the hot path.

@wemeetagain yeah that's the best way, even better than we increase Uint8Array by 1 manually

Increase nonce from 1e6 to 2e6:

nonceToBytes x 2.20 ops/sec ±1.79% (10 runs sampled)
increaseBytes x 472 ops/sec ±0.49% (89 runs sampled)
maintain same DataView x 679 ops/sec ±0.64% (88 runs sampled)

this is the same optimization @dapplion did for ssz where he maintained both Uint8Array and DataView, in our a case we should represent a Nonce as an uint, Uint8Array and DataView

[dapplion]

nonceToBytes() takes > 1% of cpu time, it's all most the time we call as-sha256.digest() or uncompress gossip messages so I think it's worth to improve it if we can

Agree it's worth improving it as the fix is really simple 👍