Re: TCP reaching to maximum throughput after a long time

From	Yuchung Cheng <ycheng@google.com>
Newsgroups	linux.kernel
Subject	Re: TCP reaching to maximum throughput after a long time
Date	2016-04-13 05:10 +0200
Message-ID	<rnjlL-29L-1@gated-at.bofh.it> (permalink)
References	(4 earlier) <rncWZ-4S9-3@gated-at.bofh.it> <rncX0-4S9-19@gated-at.bofh.it> <rnd6G-4Yr-15@gated-at.bofh.it> <rndgm-52b-7@gated-at.bofh.it> <rnem6-61z-15@gated-at.bofh.it>
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On Tue, Apr 12, 2016 at 2:40 PM, Ben Greear <greearb@candelatech.com> wrote:
> On 04/12/2016 01:29 PM, Eric Dumazet wrote:
>>
>> On Tue, 2016-04-12 at 13:23 -0700, Ben Greear wrote:
>>
>>> It worked well enough for years that I didn't even know other algorithms
>>> were
>>> available.  It was broken around 4.0 time, and I reported it to the list,
>>> and no one seemed to really care enough to do anything about it.  I
>>> changed
>>> to reno and ignored the problem as well.
>>>
>>> It is trivially easy to see the regression when using ath10k NIC, and
>>> from this email
>>> thread, I guess other NICs have similar issues.
>>
>>
>> Since it is so trivial, why don't you start a bisection ?
>
>
> I vaguely remember doing a bisect, but I can't find any email about
> that, so maybe I didn't.  At any rate, it is somewhere between 3.17 and 4.0.
> From memory, it was between 3.19 and 4.0, but I am not certain of that.
>
> Neil's suggestion, from the thread below, is that it was likely:  "605ad7f
> tcp: refine TSO autosizing"
>
> Here is previous email thread:
>
> https://www.mail-archive.com/netdev@vger.kernel.org/msg80803.html
>
> This one has a link to a pcap I made at the time:
>
> https://www.mail-archive.com/netdev@vger.kernel.org/msg80890.html
based on the prev thread I propose we disable hystart ack-train. It is
brittle under various circumstances. We've disabled that at Google for
years.

>
>>
>> I asked a capture, I did not say ' switch to Reno or whatever ', right ?
>>
>> Guessing is nice, but investigating and fixing is better.
>>
>> Do not assume that nothing can be done, please ?
>
>
> Thanks,
> Ben
>
> --
> Ben Greear <greearb@candelatech.com>
> Candela Technologies Inc  http://www.candelatech.com
>

Thread

TCP reaching to maximum throughput after a long time "Machani, Yaniv" <yanivma@ti.com> - 2016-04-12 14:20 +0200
  Re: TCP reaching to maximum throughput after a long time Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-12 17:00 +0200
    Re: TCP reaching to maximum throughput after a long time Ben Greear <greearb@candelatech.com> - 2016-04-12 17:10 +0200
      RE: TCP reaching to maximum throughput after a long time "Machani, Yaniv" <yanivma@ti.com> - 2016-04-12 21:40 +0200
        Re: TCP reaching to maximum throughput after a long time Ben Greear <greearb@candelatech.com> - 2016-04-12 22:20 +0200
          Re: TCP reaching to maximum throughput after a long time Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-12 22:20 +0200
            Re: TCP reaching to maximum throughput after a long time Ben Greear <greearb@candelatech.com> - 2016-04-12 22:30 +0200
              Re: TCP reaching to maximum throughput after a long time Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-12 22:40 +0200
                Re: TCP reaching to maximum throughput after a long time Ben Greear <greearb@candelatech.com> - 2016-04-12 23:50 +0200
                Re: TCP reaching to maximum throughput after a long time Yuchung Cheng <ycheng@google.com> - 2016-04-13 05:10 +0200
                Re: TCP reaching to maximum throughput after a long time Eric Dumazet <eric.dumazet@gmail.com> - 2016-04-13 05:40 +0200
                RE: TCP reaching to maximum throughput after a long time "Machani, Yaniv" <yanivma@ti.com> - 2016-04-13 22:30 +0200
    Re: TCP reaching to maximum throughput after a long time Yuchung Cheng <ycheng@google.com> - 2016-04-12 19:10 +0200

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