Re: TCP reaching to maximum throughput after a long time

From	Ben Greear <greearb@candelatech.com>
Newsgroups	linux.kernel
Subject	Re: TCP reaching to maximum throughput after a long time
Date	2016-04-12 23:50 +0200
Message-ID	<rnem6-61z-15@gated-at.bofh.it> (permalink)
References	(3 earlier) <rncki-4di-21@gated-at.bofh.it> <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>
Organization	Candela Technologies

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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

>
> 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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