netdev - Re: TCP and BBR: reproducibly low cwnd and bandwidth

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Date:   Fri, 16 Feb 2018 18:00:21 +0100
From:   Oleksandr Natalenko <oleksandr@...alenko.name>
To:     Neal Cardwell <ncardwell@...gle.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        Yuchung Cheng <ycheng@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Jerry Chu <hkchu@...gle.com>
Subject: Re: TCP and BBR: reproducibly low cwnd and bandwidth

Hi!

On pátek 16. února 2018 17:45:56 CET Neal Cardwell wrote:
> Eric raises a good question: bare metal vs VMs.
> 
> Oleksandr, your first email mentioned KVM VMs and virtio NICs. Your
> second e-mail did not seem to mention if those results were for bare
> metal or a VM scenario: can you please clarify the details on your
> second set of tests?

Ugh, so many letters simultaneously… I'll answer them one by one if you don't 
mind :).

Both the first and the second set of tests were performed on 2 KVM VMs, but 
from now I'll test everything using real HW only to exclude potential 
influence of virtualisation. Also, as I've already pointed out, on the real HW 
the difference is even bigger (~10 times).

Now, I'm going to answer other emails of yours, including the actual results 
from the real HW and tcpdump output as requested.

Thanks!

Regards,
  Oleksandr