From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Furniss Date: Wed, 04 May 2005 18:54:49 +0000 Subject: Re: [LARTC] Unshapeable traffic Message-Id: <42791A79.3040805@dsl.pipex.com> List-Id: References: <1294422007.20050503233431@wp.pl> In-Reply-To: <1294422007.20050503233431@wp.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Tomasz Wrona wrote: > AF> Do you know roughly how many active connections you have? > > Up to 30K. I think this could be the problem - If 30k connections all tried to send through 4mbit then a quick prod at xcalc tells me that each would get to send 1 1500 byte packet every 90 seconds. > > However I just found propably reason of issue... > > As p2p is both direction transfer most of it sends large ACK packets. > After short investigation there are some facts: > > 1) 40% of p2p ACK packets have payload larger than 1KB, other are regular > ACKs > > 2) 15% of all other traffic ACKs are longer than 1KB, 85% are regular > ACKs. Maybe - depends how you are testing, remember that all tcp packets have ack set after the initial handshake. I know p2p like bittorrent does use a single connection in full duplex , but I never noticed it hurting upstream shaping - it does make downstream more bursty as the empty acks can get sent ahead of the piggybacked ones stuck in the queue and ack a large chunk of data. > > I have priority class only for regular short ACKs, so other goes to > custom p2p class. > Cause ACKs have to be send after receiving some data propably that's why I can't > slow down traffic to defined value. Every time customer receive p2p data, > sends LARGE ACK. Outcome is that shaping p2p upload have impact on > p2p download and vice versa or in other words, to shape upload, shape > download also. > Giving extra prio for large ACKs would be suicide. I suppose the only > way to shape p2p is to dominate it by hard limits [up/down]. > > Please correct me if it's fake [and give an advise ;)]. > Maybe limiting the number of connections per user would be best - if you can. Andy. _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc