[Bloat] tackling torrent on a 10mbit uplink (100mbit down)

[Dave Taht]

sometimes I pick the wrong week to actually try to benchmark a
protocol in the wild.

https://torrentfreak.com/popular-torrents-being-sabotaged-by-ipv6-peer-flood-150619/

On Fri, Jun 19, 2015 at 9:01 AM, Dave Taht <dave.taht at gmail.com> wrote:
> I just downloaded and seeded 4 popular torrents overnight using  the
> latest version of the transmission-gtk client. I have not paid much
> attention to this app or protocol of late (about 2.5 years since last
> I did this), I got a little sparked by wanting to test cdg, but did
> not get that far.
>
> Some egress stats this morning (fq_codel on the uplink)
>
> bytes 32050522339
> packets 3379478
> dropped 702799
> percent 20.80%
> maxpacket 28614
>
> Some notes:
>
> 1) The link stayed remarkably usable:
>
> http://snapon.lab.bufferbloat.net/~d/withtorrent/vs64connectedpeers.png
>
> This graph shows what happened when one of the 4 torrents completed.
>
> The percentage of bandwidth the uplink on this test got was a bit
> larger than I expected.
>
> Subjectively, web browsing was slower but usable, and my other normal
> usages (like ssh and mosh and google music over quic) were seemingly
> unaffected. (latency for small flows stayed pretty flat)
>
> 2) even with 69 peers going at peak, I generally did not get anywhere
> near saturating the 100mbit downlink with torrent alone.
>
> 3) Offloads are a pita. Merely counting "packets" here does not show
> the real truth of what's going on (max "packet" of 28614 bytes!?), so
> linux, benchmarkers, and so on, should also be counting bytes dropped
> these days. (cake does peeling of superpackets but I was not testing
> that, and it too does not return bytes dropped)
>
> 4) *All* the traffic was udp. (uTP) Despite ipv6 being enabled (with
> two source specific ipv6 ips), I did not see any ipv6 peers connect.
> Bug? Death of torrent over ipv6? Blocking? What?
>
> 5) transmission-generated uplink traffic seemed "bursty", but I did
> not tear apart the data or code. I will track queue length next time.
>
> 6) Although transmission seems to support setting the diffserv bytes,
> it did not do so on the udp marked traffic. I think that was a tcp
> only option. Also it is incorrect for ipv6 (not using IPV6_TCLASS). I
> had figured (before starting the test) that this was going to be a
> good test of cake's diffserv support. Sigh. Is there some other client
> I could use?
>
> 7) transmission ate a metric ton of cpu (30% on a i3) at these speeds.
>
> 8) My (cable) link actually is 140mbit down, 11 up. I did not much
> care for asymmetric networks when the ratios were 6x1, so 13x1 is way
> up there....
>
> Anyway, 20% packet loss of the "right" packets was survivable. I will
> subject myself to the same test on other fq or aqms. And, if I can
> force myself to, with no aqm or fq. For SCIENCE!
>
> Attention, DMCA lawyers: Please send takedown notices to
> bufferbloat-research@/dev/null.org . One of the things truly
> astonishing about this is that in 12 hours in one night I downloaded
> more stuff than I could ever watch (mp4) or listen to (even in flac
> format) in several days of dedicated consumption. And it all just got
> rm -rf'd. It occurs to me there is a human upper bound to how much
> data one would ever want to consume, and we cracked that limit at
> 20mbit, with only 4k+ video driving demand any harder. When we started
> bufferbloat.net 20mbit downlinks were the best you could easily get.
>
>
>
> --
> Dave Täht
> worldwide bufferbloat report:
> http://www.dslreports.com/speedtest/results/bufferbloat
> And: What will it take to vastly improve wifi for everyone?
> https://plus.google.com/u/0/explore/makewififast



-- 
Dave Täht
worldwide bufferbloat report:
http://www.dslreports.com/speedtest/results/bufferbloat
And:
What will it take to vastly improve wifi for everyone?
https://plus.google.com/u/0/explore/makewififast