Message ID | 1263329126-19756-1-git-send-email-fw@strlen.de |
---|---|
State | Accepted, archived |
Delegated to: | stephen hemminger |
Headers | show |
Florian Westphal wrote: Thanks Florian. A few minor suggestions below. > diff --git a/man/man8/tc-drr.8 b/man/man8/tc-drr.8 > new file mode 100644 > index 0000000..5fcb0eb > --- /dev/null > +++ b/man/man8/tc-drr.8 > @@ -0,0 +1,89 @@ > +.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. next class or next flow? > +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 > +# 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 > +hash filter: flow filter > + > +.B tc qdisc add dev .. drr > +.B for i in .. 1024;do > +.B tc class add dev .. classid $handle:$(print %x $i) > +.B tc qdisc add dev .. fifo limit 16 > +.B done > +.B tc filter add .. protocol ip .. $handle flow hash keys src,dst divisor 1024 perturb 10 To mimic SFQ, the filter needs to use "keys src,dst,proto,proto-src,proto-dst". > + > + > +.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. > + -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Patrick McHardy <kaber@trash.net> wrote:
> Thanks Florian. A few minor suggestions below.
Thanks Patrick, I'll add all of your suggestions
to the man page in the next round of this patch.
I'll wait a few days, maybe someone else has other ideas.
Thanks again for reviewing,
Florian
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diff --git a/man/man8/tc-drr.8 b/man/man8/tc-drr.8 new file mode 100644 index 0000000..5fcb0eb --- /dev/null +++ b/man/man8/tc-drr.8 @@ -0,0 +1,89 @@ +.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. +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 +# 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 +hash filter: + +.B tc qdisc add dev .. drr +.B for i in .. 1024;do +.B tc class add dev .. classid $handle:$(print %x $i) +.B tc qdisc add dev .. fifo limit 16 +.B done +.B tc filter add .. protocol ip .. $handle flow hash keys src,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. + diff --git a/man/man8/tc.8 b/man/man8/tc.8 index 8c0880f..e17ce68 100644 --- a/man/man8/tc.8 +++ b/man/man8/tc.8 @@ -367,6 +367,7 @@ print rates in IEC units (ie. 1K = 1024). was written by Alexey N. Kuznetsov and added in Linux 2.2. .SH SEE ALSO .BR tc-cbq (8), +.BR tc-drr (8), .BR tc-htb (8), .BR tc-sfq (8), .BR tc-red (8),
Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: Florian Westphal <fw@strlen.de> --- man/man8/tc-drr.8 | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++ man/man8/tc.8 | 1 + 2 files changed, 90 insertions(+), 0 deletions(-) create mode 100644 man/man8/tc-drr.8