Re: Issues with a Large Fat pipe Network simulation

From: Pieter de Boer (pieter_at_thedarkside.nl)
Date: 06/21/05

  • Next message: Luigi Rizzo: "Re: Issues with a Large Fat pipe Network simulation" 
    Date: Tue, 21 Jun 2005 19:13:44 +0200
To: Luigi Rizzo <rizzo@icir.org>

    Luigi Rizzo wrote:

    >>However.. when I deleted the pipe rules on 'network', the speed suddenly
    >>went up to around 800mbit/s too! I remade them, and voila, 200mbit/s.
    > network emulation is a tricky job :)
    It sure is, so I'm happy you're trying to help out :)

    > in any case i believe what happens is the following.
    >
    > The pipe has a default size of 50 slots, which at 1500 bytes is
    > little above 64k. If the sender is bursting a large number of packets,
    > it may well overflow the pipe's queue causing a backoff (which
    > may simply be immediate, or delayed, depending on how you configure
    > various things).
    >
    > I believe setting the queue size in the pipe to a value larger than
    > the window should fix things.
    I had the same thought, so I already fiddled with it a bit. Because you
    brought it up I tested the following this evening:
    send/recv spaces at 128KB

    00001: unlimited 0 ms 50 sl. 1 queues (1 buckets) droptail
    00002: unlimited 0 ms 50 sl. 1 queues (1 buckets) droptail

    I'm getting 300-400mbit/s (which is higher than yesterday; it seems the
    speed creeps up a bit after a while).

    00001: unlimited 0 ms 100 sl. 1 queues (1 buckets) droptail
    00002: unlimited 0 ms 100 sl. 1 queues (1 buckets) droptail

    I'm getting 300-400mbit/s.

    There doesn't seem to be a direct relation between the pipe's queuing
    slots and the throughput. Setting the send/recvspaces to 65535 again
    does give me an immediate throughput of >800mbit/s, though.

    Hope you still have some other ideas, since I'm a bit puzzled here.. 

    -- 
Pieter
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  • Next message: Luigi Rizzo: "Re: Issues with a Large Fat pipe Network simulation"