From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Soheil Hassas Yeganeh <soheil@google.com>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>, Van Jacobson <vanj@google.com>,
Jerry Chu <hkchu@google.com>
Subject: Re: TCP and BBR: reproducibly low cwnd and bandwidth
Date: Fri, 16 Feb 2018 18:37:08 +0100 [thread overview]
Message-ID: <18081951.d6t0IUddpn@natalenko.name> (raw)
In-Reply-To: <CANn89iKqSkh=3D5-arubZkYdVTbb6C=OR5vK0sMDoO6S3A0GeQ@mail.gmail.com>
Hi.
On pátek 16. února 2018 17:25:58 CET Eric Dumazet wrote:
> The way TCP pacing works, it defaults to internal pacing using a hint
> stored in the socket.
>
> If you change the qdisc while flow is alive, result could be unexpected.
I don't change a qdisc while flow is alive. Either the VM is completely
restarted, or iperf3 is restarted on both sides.
> (TCP socket remembers that one FQ was supposed to handle the pacing)
>
> What results do you have if you use standard pfifo_fast ?
Almost the same as with fq_codel (see my previous email with numbers).
> I am asking because TCP pacing relies on High resolution timers, and
> that might be weak on your VM.
Also, I've switched to measuring things on a real HW only (also see previous
email with numbers).
Thanks.
Regards,
Oleksandr
next prev parent reply other threads:[~2018-02-16 17:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 20:42 TCP and BBR: reproducibly low cwnd and bandwidth Oleksandr Natalenko
2018-02-16 15:15 ` Oleksandr Natalenko
2018-02-16 16:25 ` Eric Dumazet
2018-02-16 17:37 ` Oleksandr Natalenko [this message]
2018-02-16 16:26 ` Holger Hoffstätte
2018-02-16 16:56 ` Neal Cardwell
2018-02-16 17:13 ` Holger Hoffstätte
2018-02-16 17:35 ` Oleksandr Natalenko
2018-02-16 16:21 ` Eric Dumazet
[not found] ` <CADVnQymiswHBp32dcMvWd1WfYLpFqY4QTas8yABFQE7KKKc5ag@mail.gmail.com>
2018-02-16 16:43 ` Eric Dumazet
2018-02-16 16:45 ` Neal Cardwell
2018-02-16 17:00 ` Oleksandr Natalenko
2018-02-16 17:25 ` Oleksandr Natalenko
2018-02-16 17:56 ` Holger Hoffstätte
2018-02-16 19:54 ` Oleksandr Natalenko
2018-02-16 20:54 ` Eric Dumazet
2018-02-16 22:50 ` Eric Dumazet
2018-02-16 23:06 ` Oleksandr Natalenko
2018-02-16 22:50 ` Oleksandr Natalenko
2018-02-16 22:59 ` Eric Dumazet
2018-02-17 10:01 ` Oleksandr Natalenko
2018-02-17 18:52 ` Eric Dumazet
2018-02-18 21:04 ` Eric Dumazet
2018-02-18 21:06 ` Eric Dumazet
2018-02-18 21:49 ` Oleksandr Natalenko
2018-02-18 22:24 ` Eric Dumazet
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