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.TH HFSC 8 "31 October 2011" iproute2 Linux
HFSC \- Hierarchical Fair Service Curve's control under linux
tc qdisc add ... hfsc [ \fBdefault\fR CLASSID ]
tc class add ... hfsc [ [ \fBrt\fR SC ] [ \fBls\fR SC ] | [ \fBsc\fR SC ] ] [ \fBul\fR SC ]
\fBrt\fR : realtime service curve
\fBls\fR : linkshare service curve
\fBsc\fR : rt+ls service curve
\fBul\fR : upperlimit service curve
\(bu at least one of \fBrt\fR, \fBls\fR or \fBsc\fR must be specified
\(bu \fBul\fR can only be specified with \fBls\fR or \fBsc\fR
.IP "SC := [ [ \fBm1\fR BPS ] \fBd\fR SEC ] \fBm2\fR BPS"
\fBm1\fR : slope of the first segment
\fBd\fR : x\-coordinate of intersection
\fBm2\fR : slope of the second segment
.IP "SC := [ [ \fBumax\fR BYTE ] \fBdmax\fR SEC ] \fBrate\fR BPS"
\fBumax\fR : maximum unit of work
\fBdmax\fR : maximum delay
\fBrate\fR : rate
For description of BYTE, BPS and SEC \- please see \fBUNITS\fR
section of \fBtc\fR(8).
HFSC qdisc has only one optional parameter \- \fBdefault\fR. CLASSID specifies
the minor part of the default classid, where packets not classified by other
means (e.g. u32 filter, CLASSIFY target of iptables) will be enqueued. If
\fBdefault\fR is not specified, unclassified packets will be dropped.
HFSC class is used to create a class hierarchy for HFSC scheduler. For
explanation of the algorithm, and the meaning behind \fBrt\fR, \fBls\fR,
\fBsc\fR and \fBul\fR service curves \- please refer to \fBtc\-hfsc\fR(7).
As you can see in \fBSYNOPSIS\fR, service curve (SC) can be specified in two
ways. Either as maximum delay for certain amount of work, or as a bandwidth
assigned for certain amount of time. Obviously, \fBm1\fR is simply
Both \fBm2\fR and \fBrate\fR are mandatory. If you omit other
parameters, you will specify linear service curve.
\fBtc\fR(8), \fBtc\-hfsc\fR(7), \fBtc\-stab\fR(8)
Please direct bugreports and patches to: <>
Manpage created by Michal Soltys (