On Sat, 8 Jul 2017 09:54:20 +1000 teor teor2345@gmail.com wrote:
Tor uses multithreaded crypto already: depending on the speed of your processor, you can get up to 400 Mbps per instance (250 Mbps is typical).
In practice I don't remember seeing much more than 120-130% CPU use per process, and even that, only in brief peaks. Maybe crypto is not actually the bottleneck, but some other non-parallel operation instead.
Speaking of CPU use, is there any roadmap to phase out TAP mode circuits? IIRC those are very CPU-expensive compared to NTor. Even though now TAP counts are only 10-20% compared to NTor, could it be that those are actually responsible for something like 50%+ of total CPU usage.
You can also get a second IPv4 address, and run 2 Tor daemons on that IP address as well.
This is not always feasible and carries additional expense even if it is.
Another idea that I proposed some time ago is raising the relay-per-IP limit from 2 to 4. There are almost no 1 or 2-core CPUs anymore, and 4-core CPUs (for 4 Tor processes) are extremely common. Especially considering the ARM architecture, where it's really common now to see 4-core CPUs, with each core being relatively weak on its own.