Hi, Thanks for your reply Alex! That mailing list thread is great and contains quite some relevant pointers.
Some of my current Tor hardware (Intel C3958) is actually QAT compatible (it's the one mentioned even) so based on the information in the thread I activated to experiment: - Kernel TLS - Kernel TLS for AES-CBC - QAT kernel module - QAT itself - HardwareAccel 1 in torrc I'll monitor the differences, although I doubt it will be this simple. I also have to look in to how I can even verify that QAT and/or kTLS are being used. It's a new territory for me :). Looks like there are stats available for kTLS at least in sysctl. In between the previous mailing list thread and this one, support for OpenSSL 3.0 has been greatly improved it seems by the way. Also about RSA-1024: Intel documentation says it's "Opt-in" [1]. Any idea how one can opt-in? I can't find any sysctl parameters for this in FreeBSD. Cheers and thanks again, tornth [1] https://www.intel.com/content/www/us/en/support/articles/000093843/technologies/intel-quickassist-technology-intel-qat.html Jun 24, 2024, 21:53 by tor-relays@lists.torproject.org: > Excerpts from mail--- via tor-relays's message of June 22, 2024 5:14 pm: > >> Hi o/, >> >> During the Tor Operator Meetup I asked about Quick Assist Technology (QAT) >> support and was asked to bring it to the tor-relays mailing list so the >> network team can take a look at the question. >> >> In 2025 we're going to build one or more new servers and we're looking in to >> optimizing the performance per watt ratio since some of our current servers >> are rather power hungry ;-). >> >> I'm wondering whether QAT works for Tor to offload compression, hashing and >> encryption. In theory, looking at the nature of Tor (a lot encryption), this >> could result in a huge performance boost of 100-300% (based on other >> hashing, cryptographic and compression offload benchmarks). Support for QAT >> also has improved considerably over the years so many programs/workloads >> already work nicely with it, but I'm not sure about Tor. >> >> It looks like Tor uses [1] RSA-1024, AES-CBC, AES-CTR, Curve25519, Ed25519, >> SHA1, AES256, AES3-256. Most (no Curve- and Ed25519) should in theory also >> work with QAT [2] (although I guess only a few would impact performance >> significantly when offloaded). But the question is: does it really work? If >> not, what would be needed to make it work? Are there Tor operators who >> already utilize QAT? Does the Network Team have some insight in to this? :) >> >> Some of the potential advantages when comparing a similar amount of traffic: >> - Lower power consumption (much cheaper to run in expensive European >> countries). >> - Less CPU cycles required (= cheaper CPUs). >> - Less heat/cooling required (easier to put in distribution boxes and other >> small places). >> - Smaller physical footprint (easier to put in distribution boxes and other >> small places). >> - Alleviates some of the issues and challenges caused by Tor's single >> threaded architecture by effectively increasing bandwidth per CPU core >> considerably. >> >> With regards, >> >> tornth >> >> [1] >> https://spec.torproject.org/tor-spec/preliminaries.html?highlight=cipher#ciphers >> [2] >> https://www.intel.com/content/www/us/en/support/articles/000093843/technologies/intel-quickassist-technology-intel-qat.html >> >> _______________________________________________ >> tor-relays mailing list >> tor-relays@lists.torproject.org >> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays >> > > I previously answered this at > https://lists.torproject.org/pipermail/tor-relays/2022-April/020495.html. > In principle, it should work if you set HardwareAccel 1. However, based > on my profiling, the actual AES encryption doesn't use that much CPU > when using regular AES instructions. I couldn't find any independent QAT > benchmarks from an internet search, but > https://calomel.org/aesni_ssl_performance.html says AES-NI can reach > over 1 GB/s per core, which is far more than Tor can use. > > Cheers, > Alex. > _______________________________________________ > tor-relays mailing list > tor-relays@lists.torproject.org > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays >
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