Date: Sat, 16 May 1998 17:26:00 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: dennis@etinc.com (Dennis) Cc: julian@whistle.com, mike@smith.net.au, andre@pipeline.ch, manar@ivision.co.uk, isp@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: Bandwidth limiter available Message-ID: <199805161526.RAA04372@labinfo.iet.unipi.it> In-Reply-To: <199805161554.LAA19755@etinc.com> from "Dennis" at May 16, 98 11:52:47 am
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> Very fancy. Not what most isps are looking for, but useful. > > One question: why were the hooks put in the drivers rather than at a > higher , more generic level. The process does not have to be as intrusive > as ALTQ seems to be. Sounds like an ongoing maintenence nightmare. i guess you refer to ALTQ. The answer is, to do CBQ/WFQ you want to select the next packet to be sent at the time the interface asks for one. The current implementation of IF_DEQUEUE and friends instead implements a queue in front of the interface, and this can disturb the bandwidth allocation. If you just want a bandwidth limiter you can work at a higher level since each flow is scheduled independently of the others, so you don't care about what is downstream. One way to solve the mainteinance problem could be to make IF_DEQUEUE an upcall to a higher level queue-handling function, so that it can be modified independently of the device driver, and can work with binary-only drivers. But this still requires an upgrade of the driver once the transition is made. i don't know how many drivers are supplied in binary-only format. cheers luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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