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Diffstat (limited to 'sys-apps/iproute2/files/iproute2-2.6.29.1-hfsc.patch')
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diff --git a/sys-apps/iproute2/files/iproute2-2.6.29.1-hfsc.patch b/sys-apps/iproute2/files/iproute2-2.6.29.1-hfsc.patch deleted file mode 100644 index 4f39ded905c1..000000000000 --- a/sys-apps/iproute2/files/iproute2-2.6.29.1-hfsc.patch +++ /dev/null @@ -1,885 +0,0 @@ -http://bugs.gentoo.org/291907 - -This patch was merged from two patches extracted from this thread: -http://markmail.org/thread/qkd76gpdgefpjlfn - -Patch #1. -This patch adds detailed documentation for HFSC scheduler. It roughly -follows HFSC paper, but tries to not rely too much on math side of things. -Post-paper/Linux specific subjects (timer resolution, ul service curve, etc.) -are also discussed. - - -I've read it many times over, but it's a lengthy chunk of text - so try -to be understanding in case I made some mistakes. - - -tc-hfsc(7): explains algorithm in detail (very long) -tc-hfsc(8): explains command line options briefly -tc(8): adds references to new man pages -Makefile: adds man7 directory to install target -q_hfsc.c: minimal help text changes, consistency with tc-hfsc(8) - - -Patch #2. -This adds generic explanation about size tables. - - -tc-stab(8): Commandline + details -One thing I'm not sure, is whenever any layer2 data is included in case -of shaping directly on ppp interface (see the bottom of the man page). - - -tc_stab.c: small fixes to commandline help - - -tc_core.c: -As kernel part of things relies on cell align which is always set to -1, -I also added it to userspace computation stage. This way if someone -specified e.g. 2048 and 512 for mtu and tsize respectively, one wouldn't -end with tsize supporting mtu 4096 suddenly, New default mtu is also set -to 2048 (disregarding weirdness of setting mtu to such values). - - -Unless I missed something, this is harmless and feels cleaner, but if it's -not allowed, documentation will have to be changed back to 2047 + extra -explanation as well. - ---- iproute2/Makefile -+++ iproute2-new/Makefile -@@ -56,6 +56,8 @@ - install -m 0644 $(shell find etc/iproute2 -maxdepth 1 -type f) $(DESTDIR)$(CONFDIR) - install -m 0755 -d $(DESTDIR)$(MANDIR)/man8 - install -m 0644 $(shell find man/man8 -maxdepth 1 -type f) $(DESTDIR)$(MANDIR)/man8 -+ install -m 0755 -d $(DESTDIR)$(MANDIR)/man7 -+ install -m 0644 $(shell find man/man7 -maxdepth 1 -type f) $(DESTDIR)$(MANDIR)/man7 - ln -sf tc-bfifo.8 $(DESTDIR)$(MANDIR)/man8/tc-pfifo.8 - ln -sf lnstat.8 $(DESTDIR)$(MANDIR)/man8/rtstat.8 - ln -sf lnstat.8 $(DESTDIR)$(MANDIR)/man8/ctstat.8 ---- iproute2/man/man7/tc-hfsc.7 -+++ iproute2-new/man/man7/tc-hfsc.7 -@@ -0,0 +1,525 @@ -+.TH HFSC 7 "25 February 2009" iproute2 Linux -+.ce 1 -+\fBHIERARCHICAL FAIR SERVICE CURVE\fR -+. -+.SH "HISTORY & INTRODUCTION" -+. -+HFSC \- \fBHierarchical Fair Service Curve\fR was first presented at -+SIGCOMM'97. Developed as a part of ALTQ (ALTernative Queuing) on NetBSD, found -+its way quickly to other BSD systems, and then a few years ago became part of -+the linux kernel. Still, it's not the most popular scheduling algorithm \- -+especially if compared to HTB \- and it's not well documented from enduser's -+perspective. This introduction aims to explain how HFSC works without -+going to deep into math side of things (although some if it will be -+inevitable). -+ -+In short HFSC aims to: -+. -+.RS 4 -+.IP \fB1)\fR 4 -+guarantee precise bandwidth and delay allocation for all leaf classes (realtime -+criterion) -+.IP \fB2)\fR -+allocate excess bandwidth fairly as specified by class hierarchy (linkshare & -+upperlimit criterion) -+.IP \fB3)\fR -+minimize any discrepancy between the service curve and the actual amount of -+service provided during linksharing -+.RE -+.PP -+. -+The main "selling" point of HFSC is feature \fB(1)\fR, which is achieved by -+using nonlinear service curves (more about what it actually is later). This is -+particularly useful in VoIP or games, where not only guarantee of consistent -+bandwidth is important, but initial delay of a data stream as well. Note that -+it matters only for leaf classes (where the actual queues are) \- thus class -+hierarchy is ignored in realtime case. -+ -+Feature \fB(2)\fR is well, obvious \- any algorithm featuring class hierarchy -+(such as HTB or CBQ) strives to achieve that. HFSC does that well, although -+you might end with unusual situations, if you define service curves carelessly -+\- see section CORNER CASES for examples. -+ -+Feature \fB(3)\fR is mentioned due to the nature of the problem. There may be -+situations where it's either not possible to guarantee service of all curves at -+the same time, and/or it's impossible to do so fairly. Both will be explained -+later. Note that this is mainly related to interior (aka aggregate) classes, as -+the leafs are already handled by \fB(1)\fR. Still \- it's perfectly possible to -+create a leaf class w/o realtime service, and in such case \- the caveats will -+naturally extend to leaf classes as well. -+ -+.SH ABBREVIATIONS -+For the remaining part of the document, we'll use following shortcuts: -+.nf -+.RS 4 -+ -+RT \- realtime -+LS \- linkshare -+UL \- upperlimit -+SC \- service curve -+.fi -+. -+.SH "BASICS OF HFSC" -+. -+To understand how HFSC works, we must first introduce a service curve. -+Overall, it's a nondecreasing function of some time unit, returning amount of -+service (allowed or allocated amount of bandwidth) by some specific point in -+time. The purpose of it should be subconsciously obvious \- if a class was -+allowed to transfer not less than the amount specified by its service curve \- -+then service curve is not violated. -+ -+Still \- we need more elaborate criterion than just the above (although in -+most generic case it can be reduced to it). The criterion has to take two -+things into account: -+. -+.RS 4 -+.IP \(bu 4 -+idling periods -+.IP \(bu -+ability to "look back", so if during current active period service curve is violated, maybe it -+isn't if we count excess bandwidth received during earlier active period(s) -+.RE -+.PP -+Let's define the criterion as follows: -+.RS 4 -+.nf -+.IP "\fB(1)\fR" 4 -+For each t1, there must exist t0 in set B, so S(t1\-t0)\~<=\~w(t0,t1) -+.fi -+.RE -+. -+.PP -+Here 'w' denotes the amount of service received during some time period between t0 -+and t1. B is a set of all times, where a session becomes active after idling -+period (further denoted as 'becoming backlogged'). For a clearer picture, -+imagine two situations: -+. -+.RS 4 -+.IP \fBa)\fR 4 -+our session was active during two periods, with a small time gap between them -+.IP \fBb)\fR -+as in (a), but with a larger gap -+.RE -+. -+.PP -+Consider \fB(a)\fR \- if the service received during both periods meets -+\fB(1)\fR, then all is good. But what if it doesn't do so during the 2nd -+period ? If the amount of service received during the 1st period is bigger -+than the service curve, then it might compensate for smaller service during -+the 2nd period \fIand\fR the gap \- if the gap is small enough. -+ -+If the gap is larger \fB(b)\fR \- then it's less likely to happen (unless the -+excess bandwidth allocated during the 1st part was really large). Still, the -+larger the gap \- the less interesting is what happened in the past (e.g. 10 -+minutes ago) \- what matters is the current traffic that just started. -+ -+From HFSC's perspective, more interesting is answering the following question: -+when should we start transferring packets, so a service curve of a class is not -+violated. Or rephrasing it: How much X() amount of service should a session -+receive by time t, so the service curve is not violated. Function X() defined -+as below is the basic building block of HFSC, used in: eligible, deadline, -+virtual\-time and fit\-time curves. Of course, X() is based on equation -+\fB(1)\fR and is defined recursively: -+ -+.RS 4 -+.IP \(bu 4 -+At the 1st backlogged period beginning function X is initialized to generic -+service curve assigned to a class -+.IP \(bu -+At any subsequent backlogged period, X() is: -+.nf -+\fBmin(X() from previous period ; w(t0)+S(t\-t0) for t>=t0),\fR -+.fi -+\&... where t0 denotes the beginning of the current backlogged period. -+.RE -+. -+.PP -+HFSC uses either linear, or two\-piece linear service curves. In case of -+linear or two\-piece linear convex functions (first slope < second slope), -+min() in X's definition reduces to the 2nd argument. But in case of two\-piece -+concave functions, the 1st argument might quickly become lesser for some -+t>=t0. Note, that for some backlogged period, X() is defined only from that -+period's beginning. We also define X^(\-1)(w) as smallest t>=t0, for which -+X(t)\~=\~w. We have to define it this way, as X() is usually not an injection. -+ -+The above generic X() can be one of the following: -+. -+.RS 4 -+.IP "E()" 4 -+In realtime criterion, selects packets eligible for sending. If none are -+eligible, HFSC will use linkshare criterion. Eligible time \&'et' is calculated -+with reference to packets' heads ( et\~=\~E^(\-1)(w) ). It's based on RT -+service curve, \fIbut in case of a convex curve, uses its 2nd slope only.\fR -+.IP "D()" -+In realtime criterion, selects the most suitable packet from the ones chosen -+by E(). Deadline time \&'dt' corresponds to packets' tails -+(dt\~=\~D^(\-1)(w+l), where \&'l' is packet's length). Based on RT service -+curve. -+.IP "V()" -+In linkshare criterion, arbitrates which packet to send next. Note that V() is -+function of a virtual time \- see \fBLINKSHARE CRITERION\fR section for -+details. Virtual time \&'vt' corresponds to packets' heads -+(vt\~=\~V^(\-1)(w)). Based on LS service curve. -+.IP "F()" -+An extension to linkshare criterion, used to limit at which speed linkshare -+criterion is allowed to dequeue. Fit\-time 'ft' corresponds to packets' heads -+as well (ft\~=\~F^(\-1)(w)). Based on UL service curve. -+.RE -+ -+Be sure to make clean distinction between session's RT, LS and UL service -+curves and the above "utility" functions. -+. -+.SH "REALTIME CRITERION" -+. -+RT criterion \fIignores class hierarchy\fR and guarantees precise bandwidth and -+delay allocation. We say that packet is eligible for sending, when current real -+time is bigger than eligible time. From all packets eligible, the one most -+suited for sending, is the one with the smallest deadline time. Sounds simply, -+but consider following example: -+ -+Interface 10mbit, two classes, both with two\-piece linear service curves: -+.RS 4 -+.IP \(bu 4 -+1st class \- 2mbit for 100ms, then 7mbit (convex \- 1st slope < 2nd slope) -+.IP \(bu -+2nd class \- 7mbit for 100ms, then 2mbit (concave \- 1st slope > 2nd slope) -+.RE -+.PP -+Assume for a moment, that we only use D() for both finding eligible packets, -+and choosing the most fitting one, thus eligible time would be computed as -+D^(\-1)(w) and deadline time would be computed as D^(\-1)(w+l). If the 2nd -+class starts sending packets 1 second after the 1st class, it's of course -+impossible to guarantee 14mbit, as the interface capability is only 10mbit. -+The only workaround in this scenario is to allow the 1st class to send the -+packets earlier that would normally be allowed. That's where separate E() comes -+to help. Putting all the math aside (see HFSC paper for details), E() for RT -+concave service curve is just like D(), but for the RT convex service curve \- -+it's constructed using \fIonly\fR RT service curve's 2nd slope (in our example -+\- 7mbit). -+ -+The effect of such E() \- packets will be sent earlier, and at the same time -+D() \fIwill\fR be updated \- so current deadline time calculated from it will -+be bigger. Thus, when the 2nd class starts sending packets later, both the 1st -+and the 2nd class will be eligible, but the 2nd session's deadline time will be -+smaller and its packets will be sent first. When the 1st class becomes idle at -+some later point, the 2nd class will be able to "buffer" up again for later -+active period of the 1st class. -+ -+A short remark \- in a situation, where the total amount of bandwidth -+available on the interface is bigger than the allocated total realtime parts -+(imagine interface 10 mbit, but 1mbit/2mbit and 2mbit/1mbit classes), the sole -+speed of the interface could suffice to guarantee the times. -+ -+Important part of RT criterion is that apart from updating its D() and E(), -+also V() used by LS criterion is updated. Generally the RT criterion is -+secondary to LS one, and used \fIonly\fR if there's a risk of violating precise -+realtime requirements. Still, the "participation" in bandwidth distributed by -+LS criterion is there, so V() has to be updated along the way. LS criterion can -+than properly compensate for non\-ideal fair sharing situation, caused by RT -+scheduling. If you use UL service curve its F() will be updated as well (UL -+service curve is an extension to LS one \- see \fBUPPERLIMIT CRITERION\fR -+section). -+ -+Anyway \- careless specification of LS and RT service curves can lead to -+potentially undesired situations (see CORNER CASES for examples). This wasn't -+the case in HFSC paper where LS and RT service curves couldn't be specified -+separately. -+ -+.SH "LINKSHARING CRITERION" -+. -+LS criterion's task is to distribute bandwidth according to specified class -+hierarchy. Contrary to RT criterion, there're no comparisons between current -+real time and virtual time \- the decision is based solely on direct comparison -+of virtual times of all active subclasses \- the one with the smallest vt wins -+and gets scheduled. One immediate conclusion from this fact is that absolute -+values don't matter \- only ratios between them (so for example, two children -+classes with simple linear 1mbit service curves will get the same treatment -+from LS criterion's perspective, as if they were 5mbit). The other conclusion -+is, that in perfectly fluid system with linear curves, all virtual times across -+whole class hierarchy would be equal. -+ -+Why is VC defined in term of virtual time (and what is it) ? -+ -+Imagine an example: class A with two children \- A1 and A2, both with let's say -+10mbit SCs. If A2 is idle, A1 receives all the bandwidth of A (and update its -+V() in the process). When A2 becomes active, A1's virtual time is already -+\fIfar\fR bigger than A2's one. Considering the type of decision made by LS -+criterion, A1 would become idle for a lot of time. We can workaround this -+situation by adjusting virtual time of the class becoming active \- we do that -+by getting such time "up to date". HFSC uses a mean of the smallest and the -+biggest virtual time of currently active children fit for sending. As it's not -+real time anymore (excluding trivial case of situation where all classes become -+active at the same time, and never become idle), it's called virtual time. -+ -+Such approach has its price though. The problem is analogous to what was -+presented in previous section and is caused by non\-linearity of service -+curves: -+.IP 1) 4 -+either it's impossible to guarantee both service curves and satisfy fairness -+during certain time periods: -+ -+.RS 4 -+Recall the example from RT section, slightly modified (with 3mbit slopes -+instead of 2mbit ones): -+ -+.IP \(bu 4 -+1st class \- 3mbit for 100ms, then 7mbit (convex \- 1st slope < 2nd slope) -+.IP \(bu -+2nd class \- 7mbit for 100ms, then 3mbit (concave \- 1st slope > 2nd slope) -+ -+.PP -+They sum up nicely to 10mbit \- interface's capacity. But if we wanted to only -+use LS for guarantees and fairness \- it simply won't work. In LS context, -+only V() is used for making decision which class to schedule. If the 2nd class -+becomes active when the 1st one is in its second slope, the fairness will be -+preserved \- ratio will be 1:1 (7mbit:7mbit), but LS itself is of course -+unable to guarantee the absolute values themselves \- as it would have to go -+beyond of what the interface is capable of. -+.RE -+ -+.IP 2) 4 -+and/or it's impossible to guarantee service curves of all classes at all -+ -+.RS 4 -+Even if we didn't use virtual time and allowed a session to be "punished", -+there's a possibility that service curves of all classes couldn't be -+guaranteed for a brief period. Consider following, a bit more complicated -+example: -+ -+Root interface, classes A and B with concave and convex curve (summing up to -+root), A1 & A2 (children of A), \fIboth\fR with concave curves summing up to A, -+B1 & B2 (children of B), \fIboth\fR with convex curves summing up to B. -+ -+Assume that A2, B1 and B2 are constantly backlogged, and at some later point -+A1 becomes backlogged. We can easily choose slopes, so that even if we -+"punish" A2 for earlier excess bandwidth received, A1 will have no chance of -+getting bandwidth corresponding to its first slope. Following from the above -+example: -+ -+.nf -+A \- 7mbit, then 3mbit -+A1 \- 5mbit, then 2mbit -+A2 \- 2mbit, then 1mbit -+ -+B \- 3mbit, then 7mbit -+B1 \- 2mbit, then 5mbit -+B2 \- 1mbit, then 2mbit -+.fi -+ -+At the point when A1 starts sending, it should get 5mbit to not violate its -+service curve. A2 gets punished and doesn't send at all, B1 and B2 both keep -+sending at their 5mbit and 2mbit. But as you can see, we already are beyond -+interface's capacity \- at 12mbit. A1 could get 3mbit at most. If we used -+virtual times and kept fairness property, A1 and A2 would send at 3mbit -+together with 5:2 ratio (so respectively at ~2.14mbit and ~0.86mbit). -+.RE -+. -+.SH "UPPERLIMIT CRITERION" -+. -+UL criterion is an extensions to LS one, that permits sending packets only -+if current real time is bigger than fit\-time ('ft'). So the modified LS -+criterion becomes: choose the smallest virtual time from all active children, -+such that fit\-time < current real time also holds. Fit\-time is calculated -+from F(), which is based on UL service curve. As you can see, it's role is -+kinda similar to E() used in RT criterion. Also, for obvious reasons \- you -+can't specify UL service curve without LS one. -+ -+Main purpose of UL service curve is to limit HFSC to bandwidth available on the -+upstream router (think adsl home modem/router, and linux server as -+nat/firewall/etc. with 100mbit+ connection to mentioned modem/router). -+Typically, it's used to create a single class directly under root, setting -+linear UL service curve to available bandwidth \- and then creating your class -+structure from that class downwards. Of course, you're free to add UL service -+(linear or not) curve to any class with LS criterion. -+ -+Important part about UL service curve is, that whenever at some point in time -+a class doesn't qualify for linksharing due to its fit\-time, the next time it -+does qualify, it will update its virtual time to the smallest virtual time of -+all active children fit for linksharing. This way, one of the main things LS -+criterion tries to achieve \- equality of all virtual times across whole -+hierarchy \- is preserved (in perfectly fluid system with only linear curves, -+all virtual times would be equal). -+ -+Without that, 'vt' would lag behind other virtual times, and could cause -+problems. Consider interface with capacity 10mbit, and following leaf classes -+(just in case you're skipping this text quickly \- this example shows behavior -+that \f(BIdoesn't happen\fR): -+ -+.nf -+A \- ls 5.0mbit -+B \- ls 2.5mbit -+C \- ls 2.5mbit, ul 2.5mbit -+.fi -+ -+If B was idle, while A and C were constantly backlogged, they would normally -+(as far as LS criterion is concerned) divide bandwidth in 2:1 ratio. But due -+to UL service curve in place, C would get at most 2.5mbit, and A would get the -+remaining 7.5mbit. The longer the backlogged period, the more virtual times of -+A and C would drift apart. If B became backlogged at some later point in time, -+its virtual time would be set to (A's\~vt\~+\~C's\~vt)/2, thus blocking A from -+sending any traffic, until B's virtual time catches up with A. -+. -+.SH "SEPARATE LS / RT SCs" -+. -+Another difference from original HFSC paper, is that RT and LS SCs can be -+specified separately. Moreover \- leaf classes are allowed to have only either -+RT SC or LS SC. For interior classes, only LS SCs make sense \- Any RT SC will -+be ignored. -+. -+.SH "CORNER CASES" -+. -+Separate service curves for LS and RT criteria can lead to certain traps, -+that come from "fighting" between ideal linksharing and enforced realtime -+guarantees. Those situations didn't exist in original HFSC paper, where -+specifying separate LS / RT service curves was not discussed. -+ -+Consider interface with capacity 10mbit, with following leaf classes: -+ -+.nf -+A \- ls 5.0mbit, rt 8mbit -+B \- ls 2.5mbit -+C \- ls 2.5mbit -+.fi -+ -+Imagine A and C are constantly backlogged. As B is idle, A and C would divide -+bandwidth in 2:1 ratio, considering LS service curve (so in theory \- 6.66 and -+3.33). Alas RT criterion takes priority, so A will get 8mbit and LS will be -+able to compensate class C for only 2 mbit \- this will cause discrepancy -+between virtual times of A and C. -+ -+Assume this situation lasts for a lot of time with no idle periods, and -+suddenly B becomes active. B's virtual time will be updated to -+(A's\~vt\~+\~C's\~vt)/2, effectively landing in the middle between A's and C's -+virtual time. The effect \- B, having no RT guarantees, will be punished and -+will not be allowed to transfer until C's virtual time catches up. -+ -+If the interface had higher capacity \- for example 100mbit, this example -+would behave perfectly fine though. -+ -+Let's look a bit closer at the above example \- it "cleverly" invalidates one -+of the basic things LS criterion tries to achieve \- equality of all virtual -+times across class hierarchy. Leaf classes without RT service curves are -+literally left to their own fate (governed by messed up virtual times). -+ -+Also - it doesn't make much sense. Class A will always be guaranteed up to -+8mbit, and this is more than any absolute bandwidth that could happen from its -+LS criterion (excluding trivial case of only A being active). If the bandwidth -+taken by A is smaller than absolute value from LS criterion, the unused part -+will be automatically assigned to other active classes (as A has idling periods -+in such case). The only "advantage" is, that even in case of low bandwidth on -+average, bursts would be handled at the speed defined by RT criterion. Still, -+if extra speed is needed (e.g. due to latency), non linear service curves -+should be used in such case. -+ -+In the other words - LS criterion is meaningless in the above example. -+ -+You can quickly "workaround" it by making sure each leaf class has RT service -+curve assigned (thus guaranteeing all of them will get some bandwidth), but it -+doesn't make it any more valid. -+. -+.SH "LINUX AND TIMER RESOLUTION" -+. -+In certain situations, the scheduler can throttle itself and setup so -+called watchdog to wakeup dequeue function at some time later. In case of HFSC -+it happens when for example no packet is eligible for scheduling, and UL -+service curve is used to limit the speed at which LS criterion is allowed to -+dequeue packets. It's called throttling, and accuracy of it is dependent on -+how the kernel is compiled. -+ -+There're 3 important options in modern kernels, as far as timers' resolution -+goes: \&'tickless system', \&'high resolution timer support' and \&'timer -+frequency'. -+ -+If you have \&'tickless system' enabled, then the timer interrupt will trigger -+as slowly as possible, but each time a scheduler throttles itself (or any -+other part of the kernel needs better accuracy), the rate will be increased as -+needed / possible. The ceiling is either \&'timer frequency' if \&'high -+resolution timer support' is not available or not compiled in. Otherwise it's -+hardware dependent and can go \fIfar\fR beyond the highest \&'timer frequency' -+setting available. -+ -+If \&'tickless system' is not enabled, the timer will trigger at a fixed rate -+specified by \&'timer frequency' \- regardless if high resolution timers are -+or aren't available. -+ -+This is important to keep those settings in mind, as in scenario like: no -+tickless, no HR timers, frequency set to 100hz \- throttling accuracy would be -+at 10ms. It doesn't automatically mean you would be limited to ~0.8mbit/s -+(assuming packets at ~1KB) \- as long as your queues are prepared to cover for -+timer inaccuracy. Of course, in case of e.g. locally generated udp traffic \- -+appropriate socket size is needed as well. Short example to make it more -+understandable (assume hardcore anti\-schedule settings \- HZ=100, no HR -+timers, no tickless): -+ -+.nf -+tc qdisc add dev eth0 root handle 1:0 hfsc default 1 -+tc class add dev eth0 parent 1:0 classid 1:1 hfsc rt m2 10mbit -+.fi -+ -+Assuming packet of ~1KB size and HZ=100, that averages to ~0.8mbit \- anything -+beyond it (e.g. the above example with specified rate over 10x bigger) will -+require appropriate queuing and cause bursts every ~10 ms. As you can -+imagine, any HFSC's RT guarantees will be seriously invalidated by that. -+Aforementioned example is mainly important if you deal with old hardware \- as -+it's particularly popular for home server chores. Even then, you can easily -+set HZ=1000 and have very accurate scheduling for typical adsl speeds. -+ -+Anything modern (apic or even hpet msi based timers + \&'tickless system') -+will provide enough accuracy for superb 1gbit scheduling. For example, on one -+of basically cheap dual core AMD boards I have with following settings: -+ -+.nf -+tc qdisc add dev eth0 parent root handle 1:0 hfsc default 1 -+tc class add dev eth0 paretn 1:0 classid 1:1 hfsc rt m2 300mbit -+.fi -+ -+And simple: -+ -+.nf -+nc \-u dst.host.com 54321 </dev/zero -+nc \-l \-p 54321 >/dev/null -+.fi -+ -+\&...will yield following effects over period of ~10 seconds (taken from -+/proc/interrupts): -+ -+.nf -+319: 42124229 0 HPET_MSI\-edge hpet2 (before) -+319: 42436214 0 HPET_MSI\-edge hpet2 (after 10s.) -+.fi -+ -+That's roughly 31000/s. Now compare it with HZ=1000 setting. The obvious -+drawback of it is that cpu load can be rather extensive with servicing that -+many timer interrupts. Example with 300mbit RT service curve on 1gbit link is -+particularly ugly, as it requires a lot of throttling with minuscule delays. -+ -+Also note that it's just an example showing capability of current hardware. -+The above example (essentially 300mbit TBF emulator) is pointless on internal -+interface to begin with \- you will pretty much always want regular LS service -+curve there, and in such scenario HFSC simply doesn't throttle at all. -+ -+300mbit RT service curve (selected columns from mpstat \-P ALL 1): -+ -+.nf -+10:56:43 PM CPU %sys %irq %soft %idle -+10:56:44 PM all 20.10 6.53 34.67 37.19 -+10:56:44 PM 0 35.00 0.00 63.00 0.00 -+10:56:44 PM 1 4.95 12.87 6.93 73.27 -+.fi -+ -+So, in rare case you need those speeds with only RT service curve, or with UL -+service curve \- remember about drawbacks. -+. -+.SH "LAYER2 ADAPTATION" -+. -+Please refer to \fBtc\-stab\fR(8) -+. -+.SH "SEE ALSO" -+. -+\fBtc\fR(8), \fBtc\-hfsc\fR(8), \fBtc\-stab\fR(8) -+ -+Please direct bugreports and patches to: <net...@vger.kernel.org> -+. -+.SH "AUTHOR" -+. -+Manpage created by Michal Soltys (sol...@ziu.info) ---- iproute2/man/man8/tc.8 -+++ iproute2-new/man/man8/tc.8 -@@ -368,12 +368,15 @@ - .SH SEE ALSO - .BR tc-cbq (8), - .BR tc-htb (8), -+.BR tc-hfsc (8), -+.BR tc-hfsc (7), - .BR tc-sfq (8), - .BR tc-red (8), - .BR tc-tbf (8), - .BR tc-pfifo (8), - .BR tc-bfifo (8), - .BR tc-pfifo_fast (8), -+.BR tc-stab (8), - .br - .RB "User documentation at " http://lartc.org/ ", but please direct bugreports and patches to: " <netdev@vger.kernel.org> - ---- iproute2/man/man8/tc-hfsc.8 -+++ iproute2-new/man/man8/tc-hfsc.8 -@@ -0,0 +1,61 @@ -+.TH HFSC 8 "25 February 2009" iproute2 Linux -+. -+.SH NAME -+HFSC \- Hierarchical Fair Service Curve's control under linux -+. -+.SH SYNOPSIS -+.nf -+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 -+.PP -+.IP "SC := [ [ \fBumax\fR BYTE ] \fBdmax\fR SEC ] \fBrate\fR BPS" -+\fBumax\fR : maximum unit of work -+\fBdmax\fR : maximum delay -+\fBrate\fR : rate -+.PP -+.fi -+For description of BYTE, BPS and SEC \- please see \fBUNITS\fR -+section of \fBtc\fR(8). -+. -+.SH DESCRIPTION (qdisc) -+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. -+. -+.SH DESCRIPTION (class) -+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 -+\fBumax\fR/\fBdmax\fR. -+ -+Both \fBm2\fR and \fBrate\fR are mandatory. If you omit other -+parameters, you will specify linear service curve. -+. -+.SH "SEE ALSO" -+. -+\fBtc\fR(8), \fBtc\-hfsc\fR(7), \fBtc\-stab\fR(8) -+ -+Please direct bugreports and patches to: <net...@vger.kernel.org> -+. -+.SH "AUTHOR" -+. -+Manpage created by Michal Soltys (sol...@ziu.info) ---- iproute2/man/man8/tc-stab.8 -+++ iproute2-new/man/man8/tc-stab.8 -@@ -0,0 +1,156 @@ -+.TH STAB 8 "25 February 2009" iproute2 Linux -+. -+.SH NAME -+tc\-stab \- Generic size table manipulations -+. -+.SH SYNOPSIS -+.nf -+tc qdisc add ... stab \\ -+.RS 4 -+[ \fBmtu\fR BYTES ] [ \fBtsize\fR SLOTS ] \\ -+[ \fBmpu\fR BYTES ] [ \fBoverhead\fR BYTES ] [ \fBlinklayer\fR TYPE ] ... -+.RE -+ -+TYPE := adsl | atm | ethernet -+.fi -+ -+For the description of BYTES \- please refer to the \fBUNITS\fR -+section of \fBtc\fR(8). -+ -+.IP \fBmtu\fR 4 -+.br -+maximum packet size we create size table for, assumed 2048 if not specified explicitly -+.IP \fBtsize\fR -+.br -+required table size, assumed 512 if not specified explicitly -+.IP \fBmpu\fR -+.br -+minimum packet size used in computations -+.IP \fBoverhead\fR -+.br -+per\-packet size overhead (can be negative) used in computations -+.IP \fBlinklayer\fR -+.br -+required linklayer adaptation. -+.PP -+. -+.SH DESCRIPTION -+. -+Size tables allow manipulation of packet size, as seen by whole scheduler -+framework (of course, the actual packet size remains the same). Adjusted packet -+size is calculated only once \- when a qdisc enqueues the packet. Initial root -+enqueue initializes it to the real packet's size. -+ -+Each qdisc can use different size table, but the adjusted size is stored in -+area shared by whole qdisc hierarchy attached to the interface (technically, -+it's stored in skb). The effect is, that if you have such setup, the last qdisc -+with a stab in a chain "wins". For example, consider HFSC with simple pfifo -+attached to one of its leaf classes. If that pfifo qdisc has stab defined, it -+will override lengths calculated during HFSC's enqueue, and in turn, whenever -+HFSC tries to dequeue a packet, it will use potentially invalid size in its -+calculations. Normal setups will usually include stab defined only on root -+qdisc, but further overriding gives extra flexibility for less usual setups. -+ -+Initial size table is calculated by \fBtc\fR tool using \fBmtu\fR and -+\fBtsize\fR parameters. The algorithm sets each slot's size to the smallest -+power of 2 value, so the whole \fBmtu\fR is covered by the size table. Neither -+\fBtsize\fR, nor \fBmtu\fR have to be power of 2 value, so the size -+table will usually support more than is required by \fBmtu\fR. -+ -+For example, with \fBmtu\fR\~=\~1500 and \fBtsize\fR\~=\~128, a table with 128 -+slots will be created, where slot 0 will correspond to sizes 0\-16, slot 1 to -+17\~\-\~32, \&..., slot 127 to 2033\~\-\~2048. Note, that the sizes -+are shifted 1 byte (normally you would expect 0\~\-\~15, 16\~\-\~31, \&..., -+2032\~\-\~2047). Sizes assigned to each slot depend on \fBlinklayer\fR parameter. -+ -+Stab calculation is also safe for an unusual case, when a size assigned to a -+slot would be larger than 2^16\-1 (you will lose the accuracy though). -+ -+During kernel part of packet size adjustment, \fBoverhead\fR will be added to -+original size, and after subtracting 1 (to land in the proper slot \- see above -+about shifting by 1 byte) slot will be calculated. If the size would cause -+overflow, more than 1 slot will be used to get the final size. It of course will -+affect accuracy, but it's only a guard against unusual situations. -+ -+Currently there're two methods of creating values stored in the size table \- -+ethernet and atm (adsl): -+ -+.IP ethernet 4 -+.br -+This is basically 1\-1 mapping, so following our example from above -+(disregarding \fBmpu\fR for a moment) slot 0 would have 8, slot 1 would have 16 -+and so on, up to slot 127 with 2048. Note, that \fBmpu\fR\~>\~0 must be -+specified, and slots that would get less than specified by \fBmpu\fR, will get -+\fBmpu\fR instead. If you don't specify \fBmpu\fR, the size table will not be -+created at all, although any \fBoverhead\fR value will be respected during -+calculations. -+.IP "atm, adsl" -+.br -+ATM linklayer consists of 53 byte cells, where each of them provides 48 bytes -+for payload. Also all the cells must be fully utilized, thus the last one is -+padded if/as necessary. -+ -+When size table is calculated, adjusted size that fits properly into lowest -+amount of cells is assigned to a slot. For example, a 100 byte long packet -+requires three 48\-byte payloads, so the final size would require 3 ATM cells -+\- 159 bytes. -+ -+For ATM size tables, 16\~bytes sized slots are perfectly enough. The default -+values of \fBmtu\fR and \fBtsize\fR create 4\~bytes sized slots. -+.PP -+. -+.SH "TYPICAL OVERHEADS" -+The following values are typical for different adsl scenarios (based on -+\fB[1]\fR and \fB[2]\fR): -+ -+.nf -+LLC based: -+.RS 4 -+PPPoA \- 14 (PPP \- 2, ATM \- 12) -+PPPoE \- 40+ (PPPoE \- 8, ATM \- 18, ethernet 14, possibly FCS \- 4+padding) -+Bridged \- 32 (ATM \- 18, ethernet 14, possibly FCS \- 4+padding) -+IPoA \- 16 (ATM \- 16) -+.RE -+ -+VC Mux based: -+.RS 4 -+PPPoA \- 10 (PPP \- 2, ATM \- 8) -+PPPoE \- 32+ (PPPoE \- 8, ATM \- 10, ethernet 14, possibly FCS \- 4+padding) -+Bridged \- 24+ (ATM \- 10, ethernet 14, possibly FCS \- 4+padding) -+IPoA \- 8 (ATM \- 8) -+.RE -+.fi -+\p There're few important things regarding the above overheads: -+. -+.IP \(bu 4 -+IPoA in LLC case requires SNAP, instead of LLC\-NLPID (see rfc2684) \- this is -+the reason, why it actually takes more space than PPPoA. -+.IP \(bu -+In rare cases, FCS might be preserved on protocols that include ethernet frame -+(Bridged and PPPoE). In such situation, any ethernet specific padding -+guaranteeing 64 bytes long frame size has to be included as well (see rfc2684). -+In the other words, it also guarantees that any packet you send will take -+minimum 2 atm cells. You should set \fBmpu\fR accordingly for that. -+.IP \(bu -+When size table is consulted, and you're shaping traffic for the sake of -+another modem/router, ethernet header (without padding) will already be added -+to initial packet's length. You should compensate for that by subtracting 14 -+from the above overheads in such case. If you're shaping directly on the router -+(for example, with speedtouch usb modem) using ppp daemon, layer2 header will -+not be added yet. -+ -+For more thorough explanations, please see \fB[1]\fR and \fB[2]\fR. -+. -+.SH "SEE ALSO" -+. -+\fBtc\fR(8), \fBtc\-hfsc\fR(7), \fBtc\-hfsc\fR(8), -+.br -+\fB[1]\fR http://ace\-host.stuart.id.au/russell/files/tc/tc\-atm/ -+.br -+\fB[2]\fR http://www.faqs.org/rfcs/rfc2684.html -+ -+Please direct bugreports and patches to: <net...@vger.kernel.org> -+. -+.SH "AUTHOR" -+. -+Manpage created by Michal Soltys (sol...@ziu.info) ---- iproute2/tc/q_hfsc.c -+++ iproute2-new/tc/q_hfsc.c -@@ -43,7 +43,7 @@ - fprintf(stderr, - "Usage: ... hfsc [ [ rt SC ] [ ls SC ] | [ sc SC ] ] [ ul SC ]\n" - "\n" -- "SC := [ [ m1 BPS ] [ d SEC ] m2 BPS\n" -+ "SC := [ [ m1 BPS ] d SEC ] m2 BPS\n" - "\n" - " m1 : slope of first segment\n" - " d : x-coordinate of intersection\n" -@@ -57,6 +57,10 @@ - " dmax : maximum delay\n" - " rate : rate\n" - "\n" -+ "Remarks:\n" -+ " - at least one of 'rt', 'ls' or 'sc' must be specified\n" -+ " - 'ul' can only be specified with 'ls' or 'sc'\n" -+ "\n" - ); - } - ---- iproute2/tc/tc_core.c -+++ iproute2-new/tc/tc_core.c -@@ -155,12 +155,12 @@ - } - - if (s->mtu == 0) -- s->mtu = 2047; -+ s->mtu = 2048; - if (s->tsize == 0) - s->tsize = 512; - - s->cell_log = 0; -- while ((s->mtu >> s->cell_log) > s->tsize - 1) -+ while ((s->mtu - 1 >> s->cell_log) > s->tsize - 1) - s->cell_log++; - - *stab = malloc(s->tsize * sizeof(__u16)); ---- iproute2/tc/tc_stab.c -+++ iproute2-new/tc/tc_stab.c -@@ -32,11 +32,15 @@ - fprintf(stderr, - "Usage: ... stab [ mtu BYTES ] [ tsize SLOTS ] [ mpu BYTES ] \n" - " [ overhead BYTES ] [ linklayer TYPE ] ...\n" -- " mtu : max packet size we create rate map for {2047}\n" -+ "TYPE := adsl | atm | ethernet\n" -+ " mtu : max packet size we create size table for {2048}\n" - " tsize : how many slots should size table have {512}\n" - " mpu : minimum packet size used in rate computations\n" - " overhead : per-packet size overhead used in rate computations\n" - " linklayer : adapting to a linklayer e.g. atm\n" -+ " mpu : minimum packet size used in size table computations\n" -+ " overhead : per-packet size overhead used in size table computations\n" -+ " linklayer : required linklayer adaptation, (adsl and atm are synonyms)\n" - "Example: ... stab overhead 20 linklayer atm\n"); - - return; |