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From: Dave Taht <dave.taht@gmail.com>
To: Adrian Kennard <a@k.gg>
Cc: bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] Bloat goes away, but with ~25% speed loss?
Date: Fri, 5 Jun 2015 12:44:38 -0700	[thread overview]
Message-ID: <CAA93jw5g9ah4_O-vtXpL43hu9PNGDVgw8B+1HinTcL7XdFmVpw@mail.gmail.com> (raw)
In-Reply-To: <5571E36E.2050607@k.gg>

On Fri, Jun 5, 2015 at 10:59 AM, Adrian Kennard <a@k.gg> wrote:
> On 05/06/2015 18:57, Kevin Darbyshire-Bryant wrote:
>> It was the uplink side and the recent adoption of Zyxel kit which
>> made me wonder out loud to AA-Andrew earlier today regarding A&A
>> bufferbloat experiences/testing on that side of things with the new
>> modems.  You're an ISP that would have some clue in that regard and
>> hence hopefully a bit of clout with the OEM to do things right (see
>> baby jumbo frames support)  It's me being curious again...sorry!
>
> We can try... Working hard to fix some showstoppers like MTU on bridging
> and the like, first.

I found dslreports.com's summary stats page:
http://www.dslreports.com/speedtest/results/isp/AS20712

not enough samples, but pretty good results. Comparisons were
interesting also. I love a competitive marketplace! (And am admiring
all the tools for continuous link monitoring AA does)

On the downlink, I am relatively uninformed until today. A lot of ISPs
have mentioned HFSC+SFQ without much details.

There are several things, conflated together, that are hurting dsl
performance on the uplink nowadays.

1) A lot of DSL modem firmware used to some form of fq buried deep in
the driver. FT used to mandate SQF, for example.

2) a lot of modems would exert ethernet hardware flow control at very
minimal packet depths. (hardware flow control is so correct for a
cable, fiber, or dsl "modem" - but as manufacturers started embedding
switches into the modem, this feature has been getting lost)

3) connecting routers used to have a default packet depth of 100 (or
less!) and thus responded to flow control more sanely than the current
linux default of 1000. I would be surprised if firebrick had a packet
depth that high.

as for 2 and 3, I know a LOT of people that passionately hold onto
their old dsl modems because they are "better" than anything newer
they've tried. I know one guy that treasures his circa-1998 one...

however, as fq_codel and pie (any latency sensitive aqm) work GREAT
with hardware flow control, this would work better than any fixed
packet limit. A metric ton of people have reported results like ipfire
did in this case:

http://planet.ipfire.org/post/ipfire-2-13-tech-preview-fighting-bufferbloat

(And I keep hoping the DCB people in DCs are taking notice.)

4) In order to get higher reliability (for things like multicast udp
tv), a lot of DSL providers use "interleaving", which incurs quite a
bit of added latency on the link.

5? anyone?

--
What will it take to vastly improve wifi for everyone?
https://plus.google.com/u/0/explore/makewififast

  reply	other threads:[~2015-06-05 19:44 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-03 21:18 Rich Brown
2015-06-04 20:01 ` Jonathan Morton
2015-06-05 14:33   ` Kevin Darbyshire-Bryant
2015-06-05 16:19     ` Dave Taht
2015-06-05 17:20       ` Kevin Darbyshire-Bryant
2015-06-05 17:23         ` Dave Taht
2015-06-05 17:25           ` Adrian Kennard
2015-06-05 17:27           ` Adrian Kennard
2015-06-05 17:44             ` Kevin Darbyshire-Bryant
2015-06-05 17:48             ` Dave Taht
2015-06-05 17:51               ` Adrian Kennard
2015-06-05 17:57                 ` Kevin Darbyshire-Bryant
2015-06-05 17:59                   ` Adrian Kennard
2015-06-05 19:44                     ` Dave Taht [this message]
2015-06-05 20:06                       ` Dave Taht
2015-06-05 22:45                         ` jb
2015-06-05 22:52                           ` Dave Taht
     [not found]                           ` <55722786.7090904@hp.com>
2015-06-06  0:32                             ` jb
2015-06-06  0:40                               ` Rick Jones
2015-06-06  3:54                         ` Aaron Wood
2015-06-06  4:13                           ` jb
2015-06-06  8:45                         ` Kevin Darbyshire-Bryant
2015-06-06  9:30                           ` jb
2015-06-06 10:04                             ` Kevin Darbyshire-Bryant
2015-06-06 10:22                               ` jb
2015-06-04 23:32 ` Aaron Wood
2015-06-04 23:38 ` Rick Jones

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