<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<div dir="auto">Hi,<br></div><div dir="auto"><br></div><div dir="auto">Thanks for your reply Alex! That mailing list thread is great and contains quite some relevant pointers.<br></div><div dir="auto"><br></div><div dir="auto">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:<br></div><div dir="auto">- Kernel TLS<br></div><div dir="auto">- Kernel TLS for AES-CBC<br></div><div dir="auto">- QAT kernel module<br></div><div dir="auto">- QAT itself<br></div><div dir="auto">- HardwareAccel 1 in torrc<br></div><div dir="auto"><br></div><div dir="auto">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.<br></div><div dir="auto"><br></div><div dir="auto">In between the previous mailing list thread and this one, support for OpenSSL 3.0 has been greatly improved it seems by the way.<br></div><div dir="auto"><br></div><div dir="auto">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.<br></div><div dir="auto"><br></div><div dir="auto">Cheers and thanks again,<br></div><div dir="auto"><br></div><div dir="auto">tornth<br></div><div dir="auto"><br></div><div dir="auto">[1] <a href="https://www.intel.com/content/www/us/en/support/articles/000093843/technologies/intel-quickassist-technology-intel-qat.html" rel="noopener noreferrer" target="_blank">https://www.intel.com/content/www/us/en/support/articles/000093843/technologies/intel-quickassist-technology-intel-qat.html</a><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto">Jun 24, 2024, 21:53 by tor-relays@lists.torproject.org:<br></div><blockquote class="tutanota_quote" style="border-left: 1px solid #93A3B8; padding-left: 10px; margin-left: 5px;"><div dir="auto">Excerpts from mail--- via tor-relays's message of June 22, 2024 5:14 pm:<br></div><blockquote><div dir="auto">Hi o/,<br></div><div dir="auto"><br></div><div dir="auto">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.<br></div><div dir="auto"><br></div><div dir="auto">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 ;-).<br></div><div dir="auto"><br></div><div dir="auto">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.<br></div><div dir="auto"><br></div><div dir="auto">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? :)<br></div><div dir="auto"><br></div><div dir="auto">Some of the potential advantages when comparing a similar amount of traffic:<br></div><div dir="auto">- Lower power consumption (much cheaper to run in expensive European countries).<br></div><div dir="auto">- Less CPU cycles required (= cheaper CPUs).<br></div><div dir="auto">- Less heat/cooling required (easier to put in distribution boxes and other small places).<br></div><div dir="auto">- Smaller physical footprint (easier to put in distribution boxes and other small places).<br></div><div dir="auto">- Alleviates some of the issues and challenges caused by Tor's single threaded architecture by effectively increasing bandwidth per CPU core considerably.<br></div><div dir="auto"><br></div><div dir="auto">With regards,<br></div><div dir="auto"><br></div><div dir="auto">tornth<br></div><div dir="auto"><br></div><div dir="auto">[1] https://spec.torproject.org/tor-spec/preliminaries.html?highlight=cipher#ciphers<br></div><div dir="auto">[2] https://www.intel.com/content/www/us/en/support/articles/000093843/technologies/intel-quickassist-technology-intel-qat.html<br></div><div dir="auto"><br></div><div dir="auto">_______________________________________________<br></div><div dir="auto">tor-relays mailing list<br></div><div dir="auto">tor-relays@lists.torproject.org<br></div><div dir="auto">https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays<br></div></blockquote><div dir="auto"><br></div><div dir="auto">I previously answered this at <br></div><div dir="auto">https://lists.torproject.org/pipermail/tor-relays/2022-April/020495.html.<br></div><div dir="auto">In principle, it should work if you set HardwareAccel 1. However, based <br></div><div dir="auto">on my profiling, the actual AES encryption doesn't use that much CPU <br></div><div dir="auto">when using regular AES instructions. I couldn't find any independent QAT <br></div><div dir="auto">benchmarks from an internet search, but <br></div><div dir="auto">https://calomel.org/aesni_ssl_performance.html says AES-NI can reach <br></div><div dir="auto">over 1 GB/s per core, which is far more than Tor can use.<br></div><div dir="auto"><br></div><div dir="auto">Cheers,<br></div><div dir="auto">Alex.<br></div><div dir="auto">_______________________________________________<br></div><div dir="auto">tor-relays mailing list<br></div><div dir="auto">tor-relays@lists.torproject.org<br></div><div dir="auto">https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays<br></div></blockquote><div dir="auto"><br></div> </body>
</html>