On 2013-09-12 11:06 , Andy Isaacson wrote:
On Wed, Sep 11, 2013 at 05:13:04PM +0200, Jeroen Massar wrote:
Are boxes that are doing these speeds running at a CPU or a network cap? Or maybe better asked, they do run at 100% usage of their cores or do they just use two/three cores to the max?
There are three main sinks of CPU usage in a well-configured large Tor relay:
- doing AES and SHA. This scales with the network bandwidth used.
- doing Montgomery multiplication for circuit creation requests.
- bookkeeping.
(4. kernel TCP overhead etc.)
[..]
Thanks that explains a lot!
Your boxes, with 12 cores and 70 GB of RAM, are quite a bit overpowered for running 500 Mbps of Tor. If you ran a Tor daemon per core, you'd be able to push around 2 Gbps of Tor traffic, easily.
Awesome, that is good to hear, as then it should be able to fill the Gig-E pipe at least theoretically.
As I am trying to avoid using too many IPs (IPv4 is constrainted, IPv6 is not, but the latter won't get much traffic), I'll try if I can get my tcp-balancer idea setup in the run of next week (low on spare cycles at the moment) and then forcing each Tor instance to use a specific core.
At least, incoming should be easy that way; the question more becomes what outgoing traffic will do, especially the bit that sends details to the authorities, I'll see how that works though ;)
Greets, Jeroen