[Cerowrt-devel] [Bloat] heisenbug: dslreports 16 flow test vs cablemodems

Sebastian Moeller moeller0 at gmx.de
Fri May 15 04:55:32 EDT 2015

Hi Lars,

On May 15, 2015, at 10:18 , Eggert, Lars <lars at netapp.com> wrote:

> On 2015-5-15, at 06:44, Aaron Wood <woody77 at gmail.com> wrote:
>> ICMP prioritization over TCP?
> Probably.

	Interesting so far I often heard ICMP echo requests are bad as they are often rate-limited and/or processed in a slow path in routers...

> Ping in parallel to TCP is a hacky way to measure latencies; not only because of prioritization, but also because you don't measure TCP send/receive buffer latencies (and they can be large, auto-tuning is not so great.)

	I guess the concurrent ICMP echo requests are a better measure for flow separation and sparse-flow-boostiing than inter-flow latency. TCP embedded timestamps would be a jacky way to measure those ;) . 

> You really need to embed timestamps in the TCP bytestream and echo them back. See the recent netperf patch I sent.

	I hope this makes into the main netperf branch…

Best Regards

> Lars
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