Date: Tue, 21 Jun 2005 19:13:44 +0200 From: Pieter de Boer <pieter@thedarkside.nl> To: Luigi Rizzo <rizzo@icir.org> Cc: freebsd-net@freebsd.org Subject: Re: Issues with a Large Fat pipe Network simulation Message-ID: <42B84AC8.7050802@thedarkside.nl> In-Reply-To: <20050621075247.D63359@xorpc.icir.org> References: <42B722EF.2090203@thedarkside.nl> <20050620135044.B35720@xorpc.icir.org> <42B731CD.1040104@thedarkside.nl> <20050621075247.D63359@xorpc.icir.org>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?42B84AC8.7050802>