How to configure the Linux kernel/net/sched

Howto configure the Linux kernel / net / sched


 * Traffic control configuration.
 * Traffic control configuration.

QoS and/or fair queueing

 * Option: NET_SCHED
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) QoS and/or fair queueing
 * When the kernel has several packets to send out over a network device, it has to decide which ones to send first, which ones to delay, and which ones to drop. This is the job of the queueing disciplines, several different algorithms for how to do this fairly have been proposed.
 * If you say N here, you will get the standard packet scheduler, which is a FIFO (first come, first served). If you say Y here, you will be able to choose from among several alternative algorithms which can then be attached to different network devices. This is useful for example if some of your network devices are real time devices that need a certain minimum data flow rate, or if you need to limit the maximum data flow rate for traffic which matches specified criteria. This code is considered to be experimental.
 * To administer these schedulers, you'll need the user-level utilities from the package iproute2+tc at . That package also contains some documentation; for more, check out .
 * This Quality of Service (QoS) support will enable you to use Differentiated Services (diffserv) and Resource Reservation Protocol (RSVP) on your Linux router if you also say Y to the corresponding classifiers below. Documentation and software is at .
 * If you say Y here and to "/proc file system" below, you will be able to read status information about packet schedulers from the file /proc/net/psched.
 * The available schedulers are listed in the following questions; you can say Y to as many as you like. If unsure, say N now.

NET_SCHED

"Packet scheduler clock source"
 * default NET_SCH_CLK_JIFFIES
 * Packet schedulers need a monotonic clock that increments at a static rate. The kernel provides several suitable interfaces, each with different properties: - high resolution (us or better) - fast to read (minimal locking, no i/o access) - synchronized on all processors - handles cpu clock frequency changes
 * but nothing provides all of the above.


 * Option: NET_SCH_CLK_JIFFIES
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Timer interrupt
 * Say Y here if you want to use the timer interrupt (jiffies) as clock source. This clock source is fast, synchronized on all processors and handles cpu clock frequency changes, but its resolution is too low for accurate shaping except at very low speed.


 * Option: NET_SCH_CLK_GETTIMEOFDAY
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) gettimeofday
 * Say Y here if you want to use gettimeofday as clock source. This clock source has high resolution, is synchronized on all processors and handles cpu clock frequency changes, but it is slow.
 * Choose this if you need a high resolution clock source but can't use the CPU's cycle counter.


 * don't allow on SMP x86 because they can have unsynchronized TSCs.
 * gettimeofday is a good alternative

- Cycle Counter 64- %ticks register 64- Time base 64- Interval Time Counter
 * Option: NET_SCH_CLK_CPU
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) CPU cycle counter
 * depends on ((X86_TSC || X86_64) && !SMP) || ALPHA || SPARC64 || PPC64 || IA64
 * Say Y here if you want to use the CPU's cycle counter as clock source. This is a cheap and high resolution clock source, but on some architectures it is not synchronized on all processors and doesn't handle cpu clock frequency changes.
 * The usable cycle counters are:
 * x86/x86_64- Timestamp Counter
 * Choose this if your CPU's cycle counter is working properly.

"Queueing/Scheduling"


 * Option: NET_SCH_CBQ
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Class Based Queueing (CBQ)
 * Say Y here if you want to use the Class-Based Queueing (CBQ) packet scheduling algorithm. This algorithm classifies the waiting packets into a tree-like hierarchy of classes; the leaves of this tree are in turn scheduled by separate algorithms.
 * See the top of  for more details.
 * CBQ is a commonly used scheduler, so if you're unsure, you should say Y here. Then say Y to all the queueing algorithms below that you want to use as leaf disciplines.
 * To compile this code as a module, choose M here: the module will be called sch_cbq.


 * Option: NET_SCH_HTB
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Hierarchical Token Bucket (HTB)
 * Say Y here if you want to use the Hierarchical Token Buckets (HTB) packet scheduling algorithm. See  for complete manual and in-depth articles.
 * HTB is very similar to CBQ regarding its goals however is has different properties and different algorithm.
 * To compile this code as a module, choose M here: the module will be called sch_htb.


 * Option: NET_SCH_HFSC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Hierarchical Fair Service Curve (HFSC)
 * Say Y here if you want to use the Hierarchical Fair Service Curve (HFSC) packet scheduling algorithm.
 * To compile this code as a module, choose M here: the module will be called sch_hfsc.


 * Option: NET_SCH_ATM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) ATM Virtual Circuits (ATM)
 * depends on ATM
 * Say Y here if you want to use the ATM pseudo-scheduler. This provides a framework for invoking classifiers, which in turn select classes of this queuing discipline.  Each class maps the flow(s) it is handling to a given virtual circuit.
 * See the top of ) for more details.
 * To compile this code as a module, choose M here: the module will be called sch_atm.


 * Option: NET_SCH_PRIO
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Multi Band Priority Queueing (PRIO)
 * Say Y here if you want to use an n-band priority queue packet scheduler.
 * To compile this code as a module, choose M here: the module will be called sch_prio.


 * Option: NET_SCH_RED
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Random Early Detection (RED)
 * Say Y here if you want to use the Random Early Detection (RED) packet scheduling algorithm.
 * See the top of  for more details.
 * To compile this code as a module, choose M here: the module will be called sch_red.


 * Option: NET_SCH_SFQ
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Stochastic Fairness Queueing (SFQ)
 * Say Y here if you want to use the Stochastic Fairness Queueing (SFQ) packet scheduling algorithm.
 * See the top of  for more details.
 * To compile this code as a module, choose M here: the module will be called sch_sfq.


 * Option: NET_SCH_TEQL
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) True Link Equalizer (TEQL)
 * Say Y here if you want to use the True Link Equalizer (TLE) packet scheduling algorithm. This queueing discipline allows the combination of several physical devices into one virtual device.
 * See the top of  for more details.
 * To compile this code as a module, choose M here: the module will be called sch_teql.


 * Option: NET_SCH_TBF
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Token Bucket Filter (TBF)
 * Say Y here if you want to use the Token Bucket Filter (TBF) packet scheduling algorithm.
 * See the top of  for more details.
 * To compile this code as a module, choose M here: the module will be called sch_tbf.


 * Option: NET_SCH_GRED
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Generic Random Early Detection (GRED)
 * Say Y here if you want to use the Generic Random Early Detection (GRED) packet scheduling algorithm for some of your network devices (see the top of  for details and references about the algorithm).
 * To compile this code as a module, choose M here: the module will be called sch_gred.


 * Option: NET_SCH_DSMARK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Differentiated Services marker (DSMARK)
 * Say Y if you want to schedule packets according to the Differentiated Services architecture proposed in RFC 2475. Technical information on this method, with pointers to associated RFCs, is available at .
 * To compile this code as a module, choose M here: the module will be called sch_dsmark.


 * Option: NET_SCH_NETEM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Network emulator (NETEM)
 * Say Y if you want to emulate network delay, loss, and packet re-ordering. This is often useful to simulate networks when testing applications or protocols.
 * To compile this driver as a module, choose M here: the module will be called sch_netem.
 * If unsure, say N.


 * Option: NET_SCH_INGRESS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Ingress Qdisc
 * Say Y here if you want to use classifiers for incoming packets. If unsure, say Y.
 * To compile this code as a module, choose M here: the module will be called sch_ingress.

"Classification"


 * Option: NET_CLS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) ean


 * Option: NET_CLS_BASIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Elementary classification (BASIC)
 * select NET_CLS
 * Say Y here if you want to be able to classify packets using only extended matches and actions.
 * To compile this code as a module, choose M here: the module will be called cls_basic.


 * Option: NET_CLS_TCINDEX
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Traffic-Control Index (TCINDEX)
 * select NET_CLS
 * Say Y here if you want to be able to classify packets based on traffic control indices. You will want this feature if you want to implement Differentiated Services together with DSMARK.
 * To compile this code as a module, choose M here: the module will be called cls_tcindex.


 * Option: NET_CLS_ROUTE4
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Routing decision (ROUTE)
 * select NET_CLS_ROUTE
 * select NET_CLS
 * If you say Y here, you will be able to classify packets according to the route table entry they matched.
 * To compile this code as a module, choose M here: the module will be called cls_route.


 * Option: NET_CLS_ROUTE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)


 * Option: NET_CLS_FW
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Netfilter mark (FW)
 * select NET_CLS
 * If you say Y here, you will be able to classify packets according to netfilter/firewall marks.
 * To compile this code as a module, choose M here: the module will be called cls_fw.


 * Option: NET_CLS_U32
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Universal 32bit comparisons w/ hashing (U32)
 * select NET_CLS
 * Say Y here to be able to classify packetes using a universal 32bit pieces based comparison scheme.
 * To compile this code as a module, choose M here: the module will be called cls_u32.


 * Option: CLS_U32_PERF
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Performance counters support
 * depends on NET_CLS_U32
 * Say Y here to make u32 gather additional statistics useful for fine tuning u32 classifiers.


 * Option: CLS_U32_MARK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Netfilter marks support
 * depends on NET_CLS_U32 && NETFILTER
 * Say Y here to be able to use netfilter marks as u32 key.


 * Option: NET_CLS_RSVP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) IPv4 Resource Reservation Protocol (RSVP)
 * select NET_CLS
 * select NET_ESTIMATOR
 * The Resource Reservation Protocol (RSVP) permits end systems to request a minimum and maximum data flow rate for a connection; this is important for real time data such as streaming sound or video.
 * Say Y here if you want to be able to classify outgoing packets based on their RSVP requests.
 * To compile this code as a module, choose M here: the module will be called cls_rsvp.


 * Option: NET_CLS_RSVP6
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) IPv6 Resource Reservation Protocol (RSVP6)
 * select NET_CLS
 * select NET_ESTIMATOR
 * The Resource Reservation Protocol (RSVP) permits end systems to request a minimum and maximum data flow rate for a connection; this is important for real time data such as streaming sound or video.
 * Say Y here if you want to be able to classify outgoing packets based on their RSVP requests and you are using the IPv6.
 * To compile this code as a module, choose M here: the module will be called cls_rsvp6.


 * Option: NET_EMATCH
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Extended Matches
 * select NET_CLS
 * Say Y here if you want to use extended matches on top of classifiers and select the extended matches below.
 * Extended matches are small classification helpers not worth writing a separate classifier for.
 * A recent version of the iproute2 package is required to use extended matches.

"Stack size"
 * Option: NET_EMATCH_STACK
 * Kernel Versions: 2.6.15.6 ...
 * depends on NET_EMATCH
 * default "32"
 * Size of the local stack variable used while evaluating the tree of ematches. Limits the depth of the tree, i.e. the number of encapsulated precedences. Every level requires 4 bytes of additional stack space.


 * Option: NET_EMATCH_CMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Simple packet data comparison
 * depends on NET_EMATCH
 * Say Y here if you want to be able to classify packets based on simple packet data comparisons for 8, 16, and 32bit values.
 * To compile this code as a module, choose M here: the module will be called em_cmp.


 * Option: NET_EMATCH_NBYTE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Multi byte comparison
 * depends on NET_EMATCH
 * Say Y here if you want to be able to classify packets based on multiple byte comparisons mainly useful for IPv6 address comparisons.
 * To compile this code as a module, choose M here: the module will be called em_nbyte.


 * Option: NET_EMATCH_U32
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) U32 key
 * depends on NET_EMATCH
 * Say Y here if you want to be able to classify packets using the famous u32 key in combination with logic relations.
 * To compile this code as a module, choose M here: the module will be called em_u32.


 * Option: NET_EMATCH_META
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Metadata
 * depends on NET_EMATCH
 * Say Y here if you want to be ablt to classify packets based on metadata such as load average, netfilter attributes, socket attributes and routing decisions.
 * To compile this code as a module, choose M here: the module will be called em_meta.


 * Option: NET_EMATCH_TEXT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Textsearch
 * depends on NET_EMATCH
 * select TEXTSEARCH
 * select TEXTSEARCH_KMP
 * select TEXTSEARCH_BM
 * select TEXTSEARCH_FSM
 * Say Y here if you want to be able to classify packets based on textsearch comparisons.
 * To compile this code as a module, choose M here: the module will be called em_text.


 * Option: NET_CLS_ACT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Actions
 * depends on EXPERIMENTAL
 * select NET_ESTIMATOR
 * Say Y here if you want to use traffic control actions. Actions get attached to classifiers and are invoked after a successful classification. They are used to overwrite the classification result, instantly drop or redirect packets, etc.
 * A recent version of the iproute2 package is required to use extended matches.


 * Option: NET_ACT_POLICE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) Traffic Policing       depends on NET_CLS_ACT        ---help--- Say Y here if you want to do traffic policing, i.e. strict bandwidth limiting. This action replaces the existing policing module.
 * To compile this code as a module, choose M here: the module will be called police.


 * Option: NET_ACT_GACT
 * Kernel Versions: 2.6.15.6 ...      tristate Generic actions       depends on NET_CLS_ACT       ---help--- Say Y here to take generic actions such as dropping and accepting packets.
 * To compile this code as a module, choose M here: the module will be called gact.


 * Option: GACT_PROB
 * Kernel Versions: 2.6.15.6 ...      bool Probability support       depends on NET_ACT_GACT       ---help--- Say Y here to use the generic action randomly or deterministically.


 * Option: NET_ACT_MIRRED
 * Kernel Versions: 2.6.15.6 ...      tristate Redirecting and Mirroring       depends on NET_CLS_ACT       ---help--- Say Y here to allow packets to be mirrored or redirected to other devices.
 * To compile this code as a module, choose M here: the module will be called mirred.


 * Option: NET_ACT_IPT
 * Kernel Versions: 2.6.15.6 ...      tristate IPtables targets       depends on NET_CLS_ACT && NETFILTER && IP_NF_IPTABLES       ---help--- Say Y here to be able to invoke iptables targets after successful classification.
 * To compile this code as a module, choose M here: the module will be called ipt.


 * Option: NET_ACT_PEDIT
 * Kernel Versions: 2.6.15.6 ...      tristate Packet Editing       depends on NET_CLS_ACT       ---help--- Say Y here if you want to mangle the content of packets.
 * To compile this code as a module, choose M here: the module will be called pedit.


 * Option: NET_ACT_SIMP
 * Kernel Versions: 2.6.15.6 ...      tristate Simple Example (Debug)       depends on NET_CLS_ACT       ---help--- Say Y here to add a simple action for demonstration purposes. It is meant as an example and for debugging purposes. It will print a configured policy string followed by the packet count to the console for every packet that passes by.
 * If unsure, say N.
 * To compile this code as a module, choose M here: the module will be called simple.


 * Option: NET_CLS_POLICE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Traffic Policing (obsolete)
 * depends on NET_CLS_ACT!=y
 * select NET_ESTIMATOR
 * Say Y here if you want to do traffic policing, i.e. strict bandwidth limiting. This option is obsoleted by the traffic policer implemented as action, it stays here for compatibility reasons.


 * Option: NET_CLS_IND
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Incoming device classification
 * depends on NET_CLS_U32 || NET_CLS_FW
 * Say Y here to extend the u32 and fw classifier to support classification based on the incoming device. This option is likely to disappear in favour of the metadata ematch.


 * Option: NET_ESTIMATOR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) Rate estimator
 * Say Y here to allow using rate estimators to estimate the current rate-of-flow for network devices, queues, etc. This module is automatically selected if needed but can be selected manually for statstical purposes.


 * 1) NET_SCHED

Linux Kernel Configuration