[Codel] fq_codel : interval servo

Jim Gettys jg at freedesktop.org
Fri Aug 31 12:40:14 EDT 2012

On 08/31/2012 08:53 AM, Rick Jones wrote:
> On 08/30/2012 11:55 PM, Eric Dumazet wrote:
>> On locally generated TCP traffic (host), we can override the 100 ms
>> interval value using the more accurate RTT estimation maintained by TCP
>> stack (tp->srtt)
>> Datacenter workload benefits using shorter feedback (say if RTT is below
>> 1 ms, we can react 100 times faster to a congestion)
>> Idea from Yuchung Cheng.
> Mileage varies of course, but what are the odds of a datacenter's
> end-system's NIC(s) being the bottleneck point?
Ergo my comment about Ethernet flow control finally being possibly more
help than hurt; clearly if the bottleneck is kept in the sending host
more of the time, it would help.

I certainly don't know how often the end-system's NIC's are the
bottleneck today without flow control; maybe a datacenter type might
have insight into that.
                    - Jim

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