[Cake] [RFC PATCH 4/5] q_netem: support delivering packets in delayed time slots
dave.taht at gmail.com
Sat Nov 18 14:02:04 EST 2017
On Sat, Nov 18, 2017 at 5:18 AM, Pete Heist <peteheist at gmail.com> wrote:
> On Nov 17, 2017, at 11:55 PM,dave.taht at gmail.com wrote:
> Slotting is a crude approximation of the behaviors of shared media such
> as cable, wifi, and LTE, which gather up a bunch of packets within a
> varying delay window and deliver them, relative to that, nearly all at
Meh. It really is "crude", and I keeping kicking about ways to somehow
emulate half (or less) duplex, variable rates around a mean, mcast,
it IS very nice to have a rate limiter that actually behaves a bit
more like wifi, and I hope to also add the new ack fitering stuff to
> One of the things I also notice in my LAN tests is latencies for different
> flows staying at more or less fixed (and different) positions relative to
> the mean in flent results. Those positions, and the mean, can change with
> each test run. Do you think this could result from the hashing to different
> hardware queues (four in my case) changing between test runs?
yes if you are using bql probably. Is it sch_mq on top?
> And is it
> worth trying to simulate this effect, or not really?
Dunno. There are a couple ways to turn it off.
> Just for info, in my case (Intel i210) the hashing is documented starting on
> page 254 of the specs:
> (220.127.116.11.1 RSS Hash Function). For TCP/UDP it uses source and destination
> addresses and ports. I suppose this could be smoothed over in testing by
> using a spread of ports for the latency test.
CEO, TekLibre, LLC
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