Re: [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02.

Am 19.05.2011 um 18:40 schrieb tsuna:

On Thu, May 19, 2011 at 1:02 AM, Hagen Paul Pfeifer [off-list ref] wrote:

quoted

So yes, it CAN be wise to choose other lower/upper bounds. But keep in
mind that we should NOT artificial limit ourself. I can image data center
scenarios where a initial RTO of <1 match perfectly.

Yes that's exactly the point I was trying to make when talking to
Alexander offline.  On today's Internet, RTTs are easily in the
hundreds of ms, and initRTO is 3s, so there's 2 orders of magnitude of
difference.  In my environment,

Exactly. This is the point. It's *your* environment. However, TCP is
general purpose. And for the wider internet 1s is know to be save. See the
measurements in the draft that Mark Allman run.

if my RTT is ~2µs, an initRTO of 200ms
means that there's a gap of 6 orders of magnitude (!).

Currently, initRTO is 3s. So you the gap is even larger. 

And yes,
although I don't work for High Frequency Trading companies in Wall
Street, I'm already buying switches full of line-rate 10Gb ports with
a port-to-port latency of 500ns for L2/L3 forwarding/switching.  I
expect this kind of network gear will quickly become prevalent in
datacenter/backend environments.

-- 
Benoit "tsuna" Sigoure
Software Engineer @ www.StumbleUpon.com

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