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[tor-bugs] #13414 [Tor]: Increase Authorities' AuthDirMaxServersPerAddr to 4 or 8 to use more processors
#13414: Increase Authorities' AuthDirMaxServersPerAddr to 4 or 8 to use more
processors
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Reporter: teor | Owner:
Type: defect | Status: new
Priority: normal | Milestone:
Component: Tor | Version:
Keywords: tor-authorities tor-router | Actual Points:
Parent ID: | Points:
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Due to the increase in logical processors per machine, a recent
conversation on the tor-dev mailing list suggested increasing the Tor
Authorities' AuthDirMaxServersPerAddr,[0] (Mortiz Bartl) either to
unlimited[1] (isis) or 4 or 8 [2][3] (mikeperry, teor).
I suggest we initially increase the consensus parameter to 8, quadrupling
CPU-bound throughput, and then, if successful, change the default in code
in a major release.
'''Details:'''
The increase in logical and physical processors per machine has
outstripped tor's ability to parallelise its workload, artificially
limiting the network throughput.[4] (AFO-Admin)
* Scarcity of IPv4 addresses, particularly in some regions
* Multiple relays sharing IPv4 addresses due to VPSs and/or NAT - see
#13234
'''Long-term:'''
Long-term work that will resolve this issue:
* Parallelise more of tor's compute workload [5]
* Optimise Cryptography, either through algorithm choice or code
refactoring
* Implement/Test/Deploy/Activate IPv6 ORPorts
'''Potential Concerns:'''
This could make Sybil attacks slightly easier, but we already mitigate
against Syblils on the same IP using the /24 filter. isis wasn't concerned
about extra Sybils from this change.[1]
This change may slightly increase the size of the consensus. However,
there are multiple upcoming plans to reduce consensus size, including:
* Consensus Diffs
* Reducing Consensus Size by Excluding the Slowest Relays
[0]: https://lists.torproject.org/pipermail/tor-
dev/2014-September/007570.html
[1]: https://lists.torproject.org/pipermail/tor-
dev/2014-September/007573.html
[2]: https://lists.torproject.org/pipermail/tor-
dev/2014-September/007574.html
[3]: https://lists.torproject.org/pipermail/tor-
dev/2014-October/007575.html
[4]: https://lists.torproject.org/pipermail/tor-
dev/2014-September/007565.html
[5]: https://lists.torproject.org/pipermail/tor-
dev/2014-September/007558.html
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13414>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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