NGINx async SSL handshake

Alexey Ivanov savetherbtz at
Sat Nov 19 08:29:54 UTC 2016

+Brian Will from Intel, to correct me if I'm wrong.

My two cents here(Intel Quick Assist specific, based on conversations during Nginx.Conf):
1) Even without hardware offload async handshake helps in cases where you have high TLS connection rates, because right now handshake is basically a 2ms+ blocking operation(specific timing depend on AVX/AVX2 support[0]) inside the event loop. Therefore after some TLS connection rate nginx performance falls off the cliff.
2) Hardware offload numbers look very impressive[1](TL;DR: 5x improvement for RSA 2048, for ECDSA, imho, it is neither impressive, nor needed). Also they prove asymmetric part of the accelerator to be future proof, so that it is possible to add new handshake types(e.g. Ed25519). Disclaimer: we did not test that hardware yet.

As for patches, you can check for:
a) nginx openssl async:
b) zlib[2]:
(Full list of docs: )

Question for Brian/Maxim: are you planning on integrating it into mainline nginx? 1000+ line diffs are usually rather hard to integrate.

[0] FWIW, speaking about OpenSSL performance: using OpenSSL 1.0.2 + Intel Xeon v2 processors with AVX2 gives 2x performance boost(over OpenSSL 1.0.1 and v1).
[2] There are also cloudflare and intel patches for zlib for faster deflation (i.e. compression only)
> On Nov 18, 2016, at 8:12 PM, Vakul Garg <vakul.garg at> wrote:
> Hi
> I am a newbie to nginx.
> I am integrating a public key hardware accelerator in OpenSSL using engine interface.
> The engine is async capable.
> Recently openssl-1.1.0 has added support for ASYNC_JOB.
> IIUC, nginx would also require changes in order to do SSL handshake in async way.
> Any pointers where can I get the nginx code changes done for async openssl
> Regards
> Vakul
> _______________________________________________
> nginx-devel mailing list
> nginx-devel at

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