It depends on what you mean by "more". More for Linux? Certainly. HTB3 seems to be a popular mechanism, and you can use IMQ to set up an intermediate device to allow shaping of both inbound and outbound traffic, using one (or more!) scheduling mechanisms in series. (In fact, there are several versions of IMQ out there. I've given links to both the projects that seem to be alive, but there may be more.) There's also ESFQ, but there doesn't seem to be much active work on that. There are forward ports to recent Linux kernels, though. QLinux has a version of H-SFQ for Linux, but again it seems to be getting long in the tooth. Unfortunately, I can't find any forward ports of that. http://luxik.cdi.cz/~devik/qos/htb/ http://www.linuximq.net/ http://pupa.da.ru/imq/ http://www.digriz.org.uk/jdg-qos-script/#qos-2.6 http://kem.p.lodz.pl/~peter/qnet/ http://lass.cs.umass.edu/software/qlinux/ There are a great many systems that I can't find a Linux version of. Cisco routers support something called "Class-Based Weighted Fair Queueing" (CBWFQ) which seems to be a hybrid of classful and classless scheduling. Cisco also has two versions of ECN, for forwards and backwards propogation. I've listed below a number of papers detailing various QoS schemes. Some of these have been implemented in other OS' (the BSDs tend to get a lot of this stuff implemented quickly for them as part of ALTQ) and some I've never seen an implementation at all. However, the papers should all give enough information to write a version for Linux. Note: ALTQ can be found at: http://www.csl.sony.co.jp/person/kjc/kjc/software.html Please note that this list is not exhaustive. Rather, I got exhausted after trying to find what was out there and what state it was currently in. QoS is a big field, if the number of papers is anything to go by. Linux only touches the fringes of it. If anyone feels particularly bored, or in need of a good ego boost, it would be cool to see if a reasonable selection of these could be introduced into Linux over the 2.7 cycle. EDF (Earliest Deadline First) http://citeseer.ist.psu.edu/13919.html BLUE (an alternative to RED) http://citeseer.ist.psu.edu/feng99blue.html AF PHB (Assured Forwarding Per-Hop Behaviour) http://citeseer.ist.psu.edu/552302.html SFB (Stochastic Fair Blue) http://citeseer.ist.psu.edu/551253.html GREEN (a pro-active variant on the theme of RED) http://citeseer.ist.psu.edu/feng02green.html SMART (Scalable Multipath Aggregated RouTing) http://citeseer.ist.psu.edu/vutukury00smart.html CSFQ (Core Stateless Fair Queueing) http://citeseer.ist.psu.edu/391.html StFQ (Start-Time Fair Queueing) http://citeseer.ist.psu.edu/goyal96starttime.html RFQ (Rainbow Fair Queueing) http://citeseer.ist.psu.edu/cao00rainbow.html PrFQ (Probabalistic Fair Queueing) http://citeseer.ist.psu.edu/anker00prfq.html ERR (Elastic Round Robin) http://citeseer.ist.psu.edu/kanhere02fair.html GFQ (Greedy Fair Queueing) http://citeseer.ist.psu.edu/690207.html PERR (Prioritized Elastic Round Robin) http://citeseer.ist.psu.edu/681127.html AOQ (Anchored Opportunity Queueing) http://citeseer.ist.psu.edu/701742.html BSFQ (Bin Sort Fair Queueing) http://citeseer.ist.psu.edu/622188.html As for the final question on what happens between enqueue and dequeue, there are various diagrams out there which show different aspects of how packets traverse the system. I've included a few links to those I could find: http://open-source.arkoon.net/kernel/kernel_net.png http://ebtables.sourceforge.net/br_fw_ia/PacketFlow.png http://ebtables.sourceforge.net/br_fw_ia/br_fw_ia.html http://www.docum.org/docum.org/kptd/ The last of these is the infamous Kernel Packet Travelling Diagram. Most links to this that I've been able to find are broken. It should be noted that the diagrams all refer to the Linux 2.4 kernel. Linux 2.6 has quite a few QoS changes to it, but I'm unclear as to whether they significantly alter any of the flows. I hope this is of some use. Or, at the very least, is an effective remedy to insomnia. :) Jonathan --- Zhenyu Wu <y030729@xxxxxxxxxxxx> wrote: > Hello, > > Normally, in addition to such qdisc scheduler > mechanisms as FIFO, PQ, WRR, WFQ, > are there any more? Then, there is a confusion on > scheduler in Linux enviroment: > Assume there is a qdisc, such as RED as a leaf qdisc > in a router, we know, if > there is packet which want to enqueue the packet, > the Function red_enqueue is > called, but when the packet leave the queue(when the > Function red_dequeue is > called)? I think it is meaningless when the pack > leaves the queue just it enterred > it. Is there anything need to be done betweent the > packet's enqueue and dequeue? > > Best, > > > _______________________________________________ > LARTC mailing list / LARTC@xxxxxxxxxxxxxxx > http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: > http://lartc.org/ > __________________________________ Do you Yahoo!? Jazz up your holiday email with celebrity designs. Learn more. http://celebrity.mail.yahoo.com _______________________________________________ LARTC mailing list / LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
