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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:18:53 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:18:53 +0000 |
commit | a0e0018c9a7ef5ce7f6d2c3ae16aecbbd16a8f67 (patch) | |
tree | 8feaf1a1932871b139b3b30be4c09c66489918be /man/man8/tc-drr.8 | |
parent | Initial commit. (diff) | |
download | iproute2-upstream/6.1.0.tar.xz iproute2-upstream/6.1.0.zip |
Adding upstream version 6.1.0.upstream/6.1.0upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | man/man8/tc-drr.8 | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/man/man8/tc-drr.8 b/man/man8/tc-drr.8 new file mode 100644 index 0000000..2fea4ee --- /dev/null +++ b/man/man8/tc-drr.8 @@ -0,0 +1,94 @@ +.TH TC 8 "January 2010" "iproute2" "Linux" +.SH NAME +drr \- deficit round robin scheduler +.SH SYNOPSIS +.B tc qdisc ... add drr +.B [ quantum +bytes +.B ] + +.SH DESCRIPTION + +The Deficit Round Robin Scheduler is a classful queuing discipline as +a more flexible replacement for Stochastic Fairness Queuing. + +Unlike SFQ, there are no built-in queues \-\- you need to add classes +and then set up filters to classify packets accordingly. +This can be useful e.g. for using RED qdiscs with different settings for particular +traffic. There is no default class \-\- if a packet cannot be classified, +it is dropped. + +.SH ALGORITHM +Each class is assigned a deficit counter, initialized to +.B quantum. + +DRR maintains an (internal) ''active'' list of classes whose qdiscs are +non-empty. This list is used for dequeuing. A packet is dequeued from +the class at the head of the list if the packet size is smaller or equal +to the deficit counter. If the counter is too small, it is increased by +.B quantum +and the scheduler moves on to the next class in the active list. + + +.SH PARAMETERS +.TP +quantum +Amount of bytes a flow is allowed to dequeue before the scheduler moves to +the next class. Defaults to the MTU of the interface. The minimum value is 1. + +.SH EXAMPLE & USAGE + +To attach to device eth0, using the interface MTU as its quantum: +.P +# tc qdisc add dev eth0 handle 1 root drr +.P +Adding two classes: +.P +# tc class add dev eth0 parent 1: classid 1:1 drr +.br +# tc class add dev eth0 parent 1: classid 1:2 drr +.P +You also need to add at least one filter to classify packets. +.P +# tc filter add dev eth0 protocol .. classid 1:1 +.P + +Like SFQ, DRR is only useful when it owns the queue \-\- it is a pure scheduler and does +not delay packets. Attaching non-work-conserving qdiscs like tbf to it does not make +sense \-\- other qdiscs in the active list will also become inactive until the dequeue +operation succeeds. Embed DRR within another qdisc like HTB or HFSC to ensure it owns the queue. +.P +You can mimic SFQ behavior by assigning packets to the attached classes using the +flow filter: + +.B tc qdisc add dev .. drr + +.B for i in .. 1024;do +.br +.B "\ttc class add dev .. classid $handle:$(print %x $i)" +.br +.B "\ttc qdisc add dev .. fifo limit 16" +.br +.B done + +.B tc filter add .. protocol ip .. $handle flow hash keys src,dst,proto,proto-src,proto-dst divisor 1024 perturb 10 + + +.SH SOURCE +.TP +o +M. Shreedhar and George Varghese "Efficient Fair +Queuing using Deficit Round Robin", Proc. SIGCOMM 95. + +.SH NOTES + +This implementation does not drop packets from the longest queue on overrun, +as limits are handled by the individual child qdiscs. + +.SH SEE ALSO +.BR tc (8), +.BR tc-htb (8), +.BR tc-sfq (8) + +.SH AUTHOR +sched_drr was written by Patrick McHardy. |