From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philippe Date: Thu, 26 Jul 2007 18:11:04 +0000 Subject: Re: [LARTC] Patch accurate packet scheduling for ATM/ADSL Message-Id: <46A8E3B8.3010003@rootsucks.com> List-Id: References: <81c11a560707250614h6d89b614t8c906f8e552248a4@mail.gmail.com> In-Reply-To: <81c11a560707250614h6d89b614t8c906f8e552248a4@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Hi ! (Sorry for my bad english...) > I use the patch > (http://ace-host.stuart.id.au/russell/files/tc/tc-atm/) for accurate > the packet scheduling on ATM/ADSL link and i think I've found a bug. I use it too, this patch is great! :o) But, with TBF, both burst and limit parameters are "affected" by the patch (or I clearly missed something). tc qdisc add dev eth1 root handle 1:0 tbf rate 100kbit \ burst 1514b limit 1514b mpu 64 atm overhead -4 tc qdisc add dev eth1 parent 1:1 handle 10:0 pfifo Before the patch (without "atm overhead -4"), using PPPoA + VC/Mux and MSS set to 1438, TBF was working normally. Just after the patch (with "atm overhead -4"), it stopped working : packets were blocked until I raise up burst and limit to 1696 (32 * 53). In this case Linux sees 1492 bytes packets on eth1 (1438 + 20 IP + 20 TCP + 14 Ethernet) Same effect with a lower MSS : burst and limit must be set to 742b (14 * 53) when MSS = 574. Pretty sure I do not unsterdand something... and wondering why I cannot set set burst/limit to 628b (only for TCP streams). To get mimimal burst/limit values, an extra atm cell is needed : mss = 1150 eth1 packet = 1204b (1150 + 40 + 14) modem packet = 1200b ( 1150 + 40 + 2 PPP + 8 AAL5) Atm cells = 25 (1200 / 48) Add one cell... and... min burst/limit = 1378 ( 26 * 53 ) TBF rate also seems to be affected: I currently have it set to 159kbit on a 128kbits upstream link and it works like a charm! :o) This is not really a problem (if it works, don't touch it) but I would like to understand... Thanks! Philippe _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc