[tor-dev] Some information about Tor relays

grarpamp grarpamp at gmail.com
Fri Aug 26 06:15:23 UTC 2016

> On Fri, Aug 26, 2016 at 01:42:38AM +0000, Liu, Zhuotao wrote:
>> We hope to have an estimate about computation capacity of Tor relays. For
>> instance, how many circuits a relay can maintain when its CPU is driven to
>> about 100%? On average, how many circuits are maintained by a busy guard
>> and
>> what the CPU utilization is. These kinds of information would be really
>> helpful.

I used to report CPU exhaustion when pushing 15-25 high circuit
flux application streams in parallel through a client and thus its guards.
To gather and characterize current limitations in an operational context
you might want to deploy a guard at your university and run some
clients through it, instrumenting various things, until something saturates.

I'd be interested in seeing estimates of what the net change in
network usable CPU headroom [1] is when adding relays using certain
fixed ratios of their own cpu/circuits and or cpu/clients and or
cpu/bandwidth capacities.

Perhaps in other words... we roughly know how a clients stream
over 3 or 6 hops might consume an additional 1Gbps added to
the network. But what does adding its CPU to the network
get us... and effect of clients/net on that. And with each box
added, are we adding the right ratio of CPU and bandwidth,
do we need a knob there to ensure optimum balanced benefit
to the net, or is it better to leave it float.

[1] Left over for network meta purposes like circuit construction,
directory services, consensus, parametric pathing computation, etc.

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