[tor-relays] Worse throughput with 0.4.8.x, on a slow CPU

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1

Hello,

Ater upgrading from Tor 0.4.7.13 to 0.4.8.9, I get a much worse bandwidth
numbers.

The CPU is Atom C2338 with two cores at 1.75 Ghz. Multiple Tor instances are
running to take advantage of both cores.

On the older version it gets about 80+80 Mbit total in+out. On the new one the
average is at most 45+45 Mbit. There are frequent periods where the bandwidth
drops to 5-10 Mbit for 3-5 seconds, while all Tor processes continue to use
100% of both CPUs, then gradually climbs back up.

Does anyone notice anything similar?

Here's how it looks for a few days on 0.4.8 then a roll-back:

···

------------------------+-------------+-------------+---------------
    today 461.94 GiB | 470.84 GiB | 932.78 GiB | 153.98 Mbit/s ########################################
12/12/23 462.81 GiB | 475.67 GiB | 938.48 GiB | 91.12 Mbit/s #######################
12/11/23 434.72 GiB | 443.08 GiB | 877.80 GiB | 85.23 Mbit/s ######################
12/10/23 446.13 GiB | 459.56 GiB | 905.70 GiB | 87.93 Mbit/s #######################
12/09/23 464.79 GiB | 473.17 GiB | 937.96 GiB | 91.07 Mbit/s #######################
12/08/23 454.67 GiB | 463.48 GiB | 918.16 GiB | 89.14 Mbit/s #######################
12/07/23 463.82 GiB | 472.84 GiB | 936.65 GiB | 90.94 Mbit/s #######################
12/06/23 670.01 GiB | 680.55 GiB | 1.32 TiB | 131.13 Mbit/s ##################################
12/05/23 808.50 GiB | 817.32 GiB | 1.59 TiB | 157.85 Mbit/s #########################################
12/04/23 854.09 GiB | 866.43 GiB | 1.68 TiB | 167.05 Mbit/s ###########################################
12/03/23 782.20 GiB | 799.00 GiB | 1.54 TiB | 153.52 Mbit/s ########################################
12/02/23 805.18 GiB | 817.91 GiB | 1.59 TiB | 157.59 Mbit/s #########################################
12/01/23 733.80 GiB | 745.35 GiB | 1.44 TiB | 143.61 Mbit/s #####################################
11/30/23 742.48 GiB | 756.56 GiB | 1.46 TiB | 145.54 Mbit/s #####################################
11/29/23 657.90 GiB | 673.66 GiB | 1.30 TiB | 129.28 Mbit/s #################################

In general, are there any tweaks to reduce relay CPU usage on a slow processor?
I did seemingly most of what is possible, ethtool, iptables, sysctl, etc.

How long before the Rust-based Tor will be ready for use on relays?

--
With respect,
Roman
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3

Hi Roman,

Yes, I am seeing something similar on 0.4.8.9 (and potentially earlier versions as well, not 100% sure when it started). I upgraded to 0.4.8.10 today hoping it would go away, but I’m seeing it again. Watching in nyx (screenshot of bandwidth graph attached), reliably every ~30 seconds, I see the bandwidth briefly plummet and the tor process CPU spike. Guard relay running in docker under ubuntu server on a Ryzen 3600 machine with 32GB RAM. Note that when the relay restarted after the upgrade today, it didn’t do this for a while (maybe an hour or so? wasn’t watching it the whole time), but then started glitching every 30s. Once it starts it does this every ~30 seconds forever. Relay has been running like this for weeks, maybe months.

best,

-jeff

1067×152 6.11 KB

···

On 12/13/23 06:15, Roman Mamedov wrote:

On the older version it gets about 80+80 Mbit total in+out. On the new one the
average is at most 45+45 Mbit. There are frequent periods where the bandwidth
drops to 5-10 Mbit for 3-5 seconds, while all Tor processes continue to use
100% of both CPUs, then gradually climbs back up.

Does anyone notice anything similar?

4

Yeah, on a more powerful host it crashes from 650 Mbit to 400 Mbit for a
couple of seconds, on a clockwork-like regular schedule like you described.
Hard to imagine devs would not have any idea what could cause specifically
this.

I am retiring my relays as soon as 0.4.7 is banned (due to a number of other
reasons as well, though).

···

On Tue, 2 Jan 2024 22:55:50 -0500 Jeff Blum <jeff@mulb.us> wrote:

Yes, I am seeing something similar on 0.4.8.9 (and potentially earlier
versions as well, not 100% sure when it started). I upgraded to 0.4.8.10
today hoping it would go away, but I'm seeing it again. Watching in nyx
(screenshot of bandwidth graph attached), reliably every ~30 seconds, I
see the bandwidth briefly plummet and the tor process CPU spike. Guard
relay running in docker under ubuntu server on a Ryzen 3600 machine with
32GB RAM. Note that when the relay restarted after the upgrade today, it
didn't do this for a while (maybe an hour or so? wasn't watching it the
whole time), but then started glitching every 30s. Once it starts it
does this every ~30 seconds forever. Relay has been running like this
for weeks, maybe months.

--
With respect,
Roman
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tor-relays mailing list
tor-relays@lists.torproject.org
https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays

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