From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, daniel@iogearbox.net, fw@strlen.de,
glenn.judd@morganstanley.com, nanditad@google.com,
ncardwell@google.com, ycheng@google.com
Subject: Re: [PATCH net-next] codel: add ce_threshold attribute
Date: Sun, 10 May 2015 19:50:57 -0400 (EDT) [thread overview]
Message-ID: <20150510.195057.467500128068846566.davem@davemloft.net> (raw)
In-Reply-To: <1431122712.22756.43.camel@edumazet-glaptop2.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 08 May 2015 15:05:12 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> For DCTCP or similar ECN based deployments on fabrics with shallow
> buffers, hosts are responsible for a good part of the buffering.
>
> This patch adds an optional ce_threshold to codel & fq_codel qdiscs,
> so that DCTCP can have feedback from queuing in the host.
>
> A DCTCP enabled egress port simply have a queue occupancy threshold
> above which ECT packets get CE mark.
>
> In codel language this translates to a sojourn time, so that one doesn't
> have to worry about bytes or bandwidth but delays.
>
> This makes the host an active participant in the health of the whole
> network.
>
> This also helps experimenting DCTCP in a setup without DCTCP compliant
> fabric.
>
> On following example, ce_threshold is set to 1ms, and we can see from
> 'ldelay xxx us' that TCP is not trying to go around the 5ms codel
> target.
>
> Queue has more capacity to absorb inelastic bursts (say from UDP
> traffic), as queues are maintained to an optimal level.
...
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied, thanks a lot Eric.
prev parent reply other threads:[~2015-05-10 23:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-08 22:05 [PATCH net-next] codel: add ce_threshold attribute Eric Dumazet
2015-05-09 21:21 ` Daniel Borkmann
2015-05-10 0:23 ` Neal Cardwell
2015-05-10 23:50 ` David Miller [this message]
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