I think that there are no qdiscs that permit to drop the oldest frame of a queue when this queue is full, but I would like to be wrong: bfifo drops arriving frames when the max queue length is reached. red also drops arriving frames in a more elaborate fashion, with a drop probability that increases above a limit and becomes a drop certitude when the max queue length is reached. sfq drops "fairly", it piles frames with same (ip source, ip dest, port source and port dest) and drops a frame from the biggest pile to favour the smaller flows. But I cannot find the qdisc that reacts like a bfifo or red qdisc but drops the oldest message of the queue when a drop is needed. Even better: a qdisc with an autodestruct algorithm for each frame in the queue that would garantee the "freshness" of each frame coming out. If you know of such qdiscs, please share. _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
vincent perrier wrote:> I think that there are no qdiscs that permit to drop the oldest > frame of a queue when this queue is full, but I would like to > be wrong: > > bfifo drops arriving frames when the max queue length is reached. > > red also drops arriving frames in a more elaborate fashion, with > a drop probability that increases above a limit and becomes > a drop certitude when the max queue length is reached. > > sfq drops "fairly", it piles frames with same (ip source, ip dest, > port source and port dest) and drops a frame from the > biggest pile to favour the smaller flows. > > But I cannot find the qdisc that reacts like a bfifo or red qdisc > but drops the oldest message of the queue when a drop is needed. > > Even better: a qdisc with an autodestruct algorithm for each > frame in the queue that would garantee the "freshness" of > each frame coming out. > > If you know of such qdiscs, please share. >What sort of thing do you want this for? I made a version of esfq head drop for use in specific circumstances. The only other thing I thought head drop generally could be usefull for is a game server, but then maybe a policer would be better than a queue WRT latency. Andy. _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> vincent perrier wrote: > > I think that there are no qdiscs that permit to drop the oldest > > frame of a queue when this queue is full ...> What sort of thing do you want this for? > ... > Andy. >Very low rate (satellite links for example) and strict priority can lead to messages waiting for a chance to be transmitted and getting old in low prio queues as higher priority messages take all the bandwidth. Vincent.> _______________________________________________ > LARTC mailing list / LARTC@mailman.ds9a.nl > http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/ >_______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
vincent perrier wrote:>>vincent perrier wrote: >> >>>I think that there are no qdiscs that permit to drop the oldest >>>frame of a queue when this queue is full ... > > >>What sort of thing do you want this for? >>... >>Andy. >> > > > Very low rate (satellite links for example) and strict priority can > lead to messages waiting for a chance to be transmitted and getting > old in low prio queues as higher priority messages take all the > bandwidth. > Vincent.Ahh - if the messages established tcp then I don''t think it will make any difference. If the messages are udp then I suppose it could help a bit - depends what you mean by messages. Andy. _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/