From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Furniss Date: Mon, 17 Oct 2005 19:20:43 +0000 Subject: Re: [LARTC] The effects of queueing on delay...(TX Ring Buffer the Message-Id: <4353F98B.8020709@dsl.pipex.com> List-Id: References: <1129064647.13493.41.camel@pgala.it.nuigalway.ie> In-Reply-To: <1129064647.13493.41.camel@pgala.it.nuigalway.ie> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Jonathan Lynch wrote: > This was down to the tx buffer size on the network card i was using. It > was an Intel 82547EI gigabit Card using the e1000 driver and operating > at 100mbit. The tx buffer was set to 256 which caused this huge delay. > The minimum the driver lets me reduce the tx buffer size using ethtool > is 80. By reducing the tx ring buffer to 80, the delay when there is > full link utilisation and a maximum queue of 10 packets was reduced from > 30ms to 10ms. > > The 3com 3c59x vortex driver uses a tx buffer of 16. I reduced the tx to > 16 on the e1000 driver, but the max throughput i could achieve on the > interface went down. > > Has anyone experimented with reducing the size of the tx buffer on this > card to get a good balance between delay and throughput ? Strange - I thought that as long as you are under rate for the link then the most htb should burst per tick is the burst size specified. That assumes one bulk class - more will make it worse. Andy. _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc