The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_dummynet.h

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    1 /*
    2  * Copyright (c) 1998-2002 Luigi Rizzo, Universita` di Pisa
    3  * Portions Copyright (c) 2000 Akamba Corp.
    4  * All rights reserved
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  * $FreeBSD: releng/5.0/sys/netinet/ip_dummynet.h 104975 2002-10-12 07:45:23Z seanc $
   28  */
   29 
   30 #ifndef _IP_DUMMYNET_H
   31 #define _IP_DUMMYNET_H
   32 
   33 /*
   34  * Definition of dummynet data structures. In the structures, I decided
   35  * not to use the macros in <sys/queue.h> in the hope of making the code
   36  * easier to port to other architectures. The type of lists and queue we
   37  * use here is pretty simple anyways.
   38  */
   39 
   40 /*
   41  * We start with a heap, which is used in the scheduler to decide when
   42  * to transmit packets etc.
   43  *
   44  * The key for the heap is used for two different values:
   45  *
   46  * 1. timer ticks- max 10K/second, so 32 bits are enough;
   47  *
   48  * 2. virtual times. These increase in steps of len/x, where len is the
   49  *    packet length, and x is either the weight of the flow, or the
   50  *    sum of all weights.
   51  *    If we limit to max 1000 flows and a max weight of 100, then
   52  *    x needs 17 bits. The packet size is 16 bits, so we can easily
   53  *    overflow if we do not allow errors.
   54  * So we use a key "dn_key" which is 64 bits. Some macros are used to
   55  * compare key values and handle wraparounds.
   56  * MAX64 returns the largest of two key values.
   57  * MY_M is used as a shift count when doing fixed point arithmetic
   58  * (a better name would be useful...).
   59  */
   60 typedef u_int64_t dn_key ;      /* sorting key */
   61 #define DN_KEY_LT(a,b)     ((int64_t)((a)-(b)) < 0)
   62 #define DN_KEY_LEQ(a,b)    ((int64_t)((a)-(b)) <= 0)
   63 #define DN_KEY_GT(a,b)     ((int64_t)((a)-(b)) > 0)
   64 #define DN_KEY_GEQ(a,b)    ((int64_t)((a)-(b)) >= 0)
   65 #define MAX64(x,y)  (( (int64_t) ( (y)-(x) )) > 0 ) ? (y) : (x)
   66 #define MY_M    16 /* number of left shift to obtain a larger precision */
   67 
   68 /*
   69  * XXX With this scaling, max 1000 flows, max weight 100, 1Gbit/s, the
   70  * virtual time wraps every 15 days.
   71  */
   72 
   73 /*
   74  * The OFFSET_OF macro is used to return the offset of a field within
   75  * a structure. It is used by the heap management routines.
   76  */
   77 #define OFFSET_OF(type, field) ((int)&( ((type *)0)->field) )
   78 
   79 /*
   80  * The maximum hash table size for queues.  This value must be a power
   81  * of 2.
   82  */
   83 #define DN_MAX_HASH_SIZE 65536
   84 
   85 /*
   86  * A heap entry is made of a key and a pointer to the actual
   87  * object stored in the heap.
   88  * The heap is an array of dn_heap_entry entries, dynamically allocated.
   89  * Current size is "size", with "elements" actually in use.
   90  * The heap normally supports only ordered insert and extract from the top.
   91  * If we want to extract an object from the middle of the heap, we
   92  * have to know where the object itself is located in the heap (or we
   93  * need to scan the whole array). To this purpose, an object has a
   94  * field (int) which contains the index of the object itself into the
   95  * heap. When the object is moved, the field must also be updated.
   96  * The offset of the index in the object is stored in the 'offset'
   97  * field in the heap descriptor. The assumption is that this offset
   98  * is non-zero if we want to support extract from the middle.
   99  */
  100 struct dn_heap_entry {
  101     dn_key key ;        /* sorting key. Topmost element is smallest one */
  102     void *object ;      /* object pointer */
  103 } ;
  104 
  105 struct dn_heap {
  106     int size ;
  107     int elements ;
  108     int offset ; /* XXX if > 0 this is the offset of direct ptr to obj */
  109     struct dn_heap_entry *p ;   /* really an array of "size" entries */
  110 } ;
  111 
  112 /*
  113  * struct dn_pkt identifies a packet in the dummynet queue, but
  114  * is also used to tag packets passed back to the various destinations
  115  * (ip_input(), ip_output(), bdg_forward()  and so on).
  116  * As such the first part of the structure must be a struct m_hdr,
  117  * followed by dummynet-specific parameters. The m_hdr must be
  118  * initialized with
  119  *   mh_type    = MT_TAG;
  120  *   mh_flags   = PACKET_TYPE_DUMMYNET;
  121  *   mh_next    = <pointer to the actual mbuf>
  122  *
  123  * mh_nextpkt, mh_data are free for dummynet use (mh_nextpkt is used to
  124  * build a linked list of packets in a dummynet queue).
  125  */
  126 struct dn_pkt {
  127     struct m_hdr hdr ;
  128 #define DN_NEXT(x)      (struct dn_pkt *)(x)->hdr.mh_nextpkt
  129 #define dn_m    hdr.mh_next     /* packet to be forwarded */
  130 
  131     struct ip_fw *rule;         /* matching rule */
  132     int dn_dir;                 /* action when packet comes out. */
  133 #define DN_TO_IP_OUT    1
  134 #define DN_TO_IP_IN     2
  135 #define DN_TO_BDG_FWD   3
  136 #define DN_TO_ETH_DEMUX 4
  137 #define DN_TO_ETH_OUT   5
  138 
  139     dn_key output_time;         /* when the pkt is due for delivery     */
  140     struct ifnet *ifp;          /* interface, for ip_output             */
  141     struct sockaddr_in *dn_dst ;
  142     struct route ro;            /* route, for ip_output. MUST COPY      */
  143     int flags ;                 /* flags, for ip_output (IPv6 ?)        */
  144 };
  145 
  146 /*
  147  * Overall structure of dummynet (with WF2Q+):
  148 
  149 In dummynet, packets are selected with the firewall rules, and passed
  150 to two different objects: PIPE or QUEUE.
  151 
  152 A QUEUE is just a queue with configurable size and queue management
  153 policy. It is also associated with a mask (to discriminate among
  154 different flows), a weight (used to give different shares of the
  155 bandwidth to different flows) and a "pipe", which essentially
  156 supplies the transmit clock for all queues associated with that
  157 pipe.
  158 
  159 A PIPE emulates a fixed-bandwidth link, whose bandwidth is
  160 configurable.  The "clock" for a pipe can come from either an
  161 internal timer, or from the transmit interrupt of an interface.
  162 A pipe is also associated with one (or more, if masks are used)
  163 queue, where all packets for that pipe are stored.
  164 
  165 The bandwidth available on the pipe is shared by the queues
  166 associated with that pipe (only one in case the packet is sent
  167 to a PIPE) according to the WF2Q+ scheduling algorithm and the
  168 configured weights.
  169 
  170 In general, incoming packets are stored in the appropriate queue,
  171 which is then placed into one of a few heaps managed by a scheduler
  172 to decide when the packet should be extracted.
  173 The scheduler (a function called dummynet()) is run at every timer
  174 tick, and grabs queues from the head of the heaps when they are
  175 ready for processing.
  176 
  177 There are three data structures definining a pipe and associated queues:
  178 
  179  + dn_pipe, which contains the main configuration parameters related
  180    to delay and bandwidth;
  181  + dn_flow_set, which contains WF2Q+ configuration, flow
  182    masks, plr and RED configuration;
  183  + dn_flow_queue, which is the per-flow queue (containing the packets)
  184 
  185 Multiple dn_flow_set can be linked to the same pipe, and multiple
  186 dn_flow_queue can be linked to the same dn_flow_set.
  187 All data structures are linked in a linear list which is used for
  188 housekeeping purposes.
  189 
  190 During configuration, we create and initialize the dn_flow_set
  191 and dn_pipe structures (a dn_pipe also contains a dn_flow_set).
  192 
  193 At runtime: packets are sent to the appropriate dn_flow_set (either
  194 WFQ ones, or the one embedded in the dn_pipe for fixed-rate flows),
  195 which in turn dispatches them to the appropriate dn_flow_queue
  196 (created dynamically according to the masks).
  197 
  198 The transmit clock for fixed rate flows (ready_event()) selects the
  199 dn_flow_queue to be used to transmit the next packet. For WF2Q,
  200 wfq_ready_event() extract a pipe which in turn selects the right
  201 flow using a number of heaps defined into the pipe itself.
  202 
  203  *
  204  */
  205 
  206 /*
  207  * per flow queue. This contains the flow identifier, the queue
  208  * of packets, counters, and parameters used to support both RED and
  209  * WF2Q+.
  210  *
  211  * A dn_flow_queue is created and initialized whenever a packet for
  212  * a new flow arrives.
  213  */
  214 struct dn_flow_queue {
  215     struct dn_flow_queue *next ;
  216     struct ipfw_flow_id id ;
  217 
  218     struct dn_pkt *head, *tail ;        /* queue of packets */
  219     u_int len ;
  220     u_int len_bytes ;
  221     long numbytes ;             /* credit for transmission (dynamic queues) */
  222 
  223     u_int64_t tot_pkts ;        /* statistics counters  */
  224     u_int64_t tot_bytes ;
  225     u_int32_t drops ;
  226 
  227     int hash_slot ;             /* debugging/diagnostic */
  228 
  229     /* RED parameters */
  230     int avg ;                   /* average queue length est. (scaled) */
  231     int count ;                 /* arrivals since last RED drop */
  232     int random ;                /* random value (scaled) */
  233     u_int32_t q_time ;          /* start of queue idle time */
  234 
  235     /* WF2Q+ support */
  236     struct dn_flow_set *fs ;    /* parent flow set */
  237     int heap_pos ;              /* position (index) of struct in heap */
  238     dn_key sched_time ;         /* current time when queue enters ready_heap */
  239 
  240     dn_key S,F ;                /* start time, finish time */
  241     /*
  242      * Setting F < S means the timestamp is invalid. We only need
  243      * to test this when the queue is empty.
  244      */
  245 } ;
  246 
  247 /*
  248  * flow_set descriptor. Contains the "template" parameters for the
  249  * queue configuration, and pointers to the hash table of dn_flow_queue's.
  250  *
  251  * The hash table is an array of lists -- we identify the slot by
  252  * hashing the flow-id, then scan the list looking for a match.
  253  * The size of the hash table (buckets) is configurable on a per-queue
  254  * basis.
  255  *
  256  * A dn_flow_set is created whenever a new queue or pipe is created (in the
  257  * latter case, the structure is located inside the struct dn_pipe).
  258  */
  259 struct dn_flow_set {
  260     struct dn_flow_set *next; /* next flow set in all_flow_sets list */
  261 
  262     u_short fs_nr ;             /* flow_set number       */
  263     u_short flags_fs;
  264 #define DN_HAVE_FLOW_MASK       0x0001
  265 #define DN_IS_RED               0x0002
  266 #define DN_IS_GENTLE_RED        0x0004
  267 #define DN_QSIZE_IS_BYTES       0x0008  /* queue size is measured in bytes */
  268 #define DN_NOERROR              0x0010  /* do not report ENOBUFS on drops  */
  269 #define DN_IS_PIPE              0x4000
  270 #define DN_IS_QUEUE             0x8000
  271 
  272     struct dn_pipe *pipe ;      /* pointer to parent pipe */
  273     u_short parent_nr ;         /* parent pipe#, 0 if local to a pipe */
  274 
  275     int weight ;                /* WFQ queue weight */
  276     int qsize ;                 /* queue size in slots or bytes */
  277     int plr ;                   /* pkt loss rate (2^31-1 means 100%) */
  278 
  279     struct ipfw_flow_id flow_mask ;
  280 
  281     /* hash table of queues onto this flow_set */
  282     int rq_size ;               /* number of slots */
  283     int rq_elements ;           /* active elements */
  284     struct dn_flow_queue **rq;  /* array of rq_size entries */
  285 
  286     u_int32_t last_expired ;    /* do not expire too frequently */
  287     int backlogged ;            /* #active queues for this flowset */
  288 
  289         /* RED parameters */
  290 #define SCALE_RED               16
  291 #define SCALE(x)                ( (x) << SCALE_RED )
  292 #define SCALE_VAL(x)            ( (x) >> SCALE_RED )
  293 #define SCALE_MUL(x,y)          ( ( (x) * (y) ) >> SCALE_RED )
  294     int w_q ;                   /* queue weight (scaled) */
  295     int max_th ;                /* maximum threshold for queue (scaled) */
  296     int min_th ;                /* minimum threshold for queue (scaled) */
  297     int max_p ;                 /* maximum value for p_b (scaled) */
  298     u_int c_1 ;                 /* max_p/(max_th-min_th) (scaled) */
  299     u_int c_2 ;                 /* max_p*min_th/(max_th-min_th) (scaled) */
  300     u_int c_3 ;                 /* for GRED, (1-max_p)/max_th (scaled) */
  301     u_int c_4 ;                 /* for GRED, 1 - 2*max_p (scaled) */
  302     u_int * w_q_lookup ;        /* lookup table for computing (1-w_q)^t */
  303     u_int lookup_depth ;        /* depth of lookup table */
  304     int lookup_step ;           /* granularity inside the lookup table */
  305     int lookup_weight ;         /* equal to (1-w_q)^t / (1-w_q)^(t+1) */
  306     int avg_pkt_size ;          /* medium packet size */
  307     int max_pkt_size ;          /* max packet size */
  308 } ;
  309 
  310 /*
  311  * Pipe descriptor. Contains global parameters, delay-line queue,
  312  * and the flow_set used for fixed-rate queues.
  313  * 
  314  * For WF2Q+ support it also has 3 heaps holding dn_flow_queue:
  315  *   not_eligible_heap, for queues whose start time is higher
  316  *      than the virtual time. Sorted by start time.
  317  *   scheduler_heap, for queues eligible for scheduling. Sorted by
  318  *      finish time.
  319  *   idle_heap, all flows that are idle and can be removed. We
  320  *      do that on each tick so we do not slow down too much
  321  *      operations during forwarding.
  322  * 
  323  */
  324 struct dn_pipe {                /* a pipe */
  325     struct dn_pipe *next ;
  326 
  327     int pipe_nr ;               /* number       */
  328     int bandwidth;              /* really, bytes/tick.  */
  329     int delay ;                 /* really, ticks        */
  330 
  331     struct      dn_pkt *head, *tail ;   /* packets in delay line */
  332 
  333     /* WF2Q+ */
  334     struct dn_heap scheduler_heap ; /* top extract - key Finish time*/
  335     struct dn_heap not_eligible_heap; /* top extract- key Start time */
  336     struct dn_heap idle_heap ; /* random extract - key Start=Finish time */
  337 
  338     dn_key V ;                  /* virtual time */
  339     int sum;                    /* sum of weights of all active sessions */
  340     int numbytes;               /* bits I can transmit (more or less). */
  341 
  342     dn_key sched_time ;         /* time pipe was scheduled in ready_heap */
  343 
  344     /*
  345      * When the tx clock come from an interface (if_name[0] != '\0'), its name
  346      * is stored below, whereas the ifp is filled when the rule is configured.
  347      */
  348     char if_name[16];
  349     struct ifnet *ifp ;
  350     int ready ; /* set if ifp != NULL and we got a signal from it */
  351 
  352     struct dn_flow_set fs ; /* used with fixed-rate flows */
  353 };
  354 
  355 #ifdef _KERNEL
  356 typedef int ip_dn_ctl_t(struct sockopt *); /* raw_ip.c */
  357 typedef void ip_dn_ruledel_t(void *); /* ip_fw.c */
  358 typedef int ip_dn_io_t(struct mbuf *m, int pipe_nr, int dir,
  359         struct ip_fw_args *fwa);
  360 extern  ip_dn_ctl_t *ip_dn_ctl_ptr;
  361 extern  ip_dn_ruledel_t *ip_dn_ruledel_ptr;
  362 extern  ip_dn_io_t *ip_dn_io_ptr;
  363 #define DUMMYNET_LOADED (ip_dn_io_ptr != NULL)
  364 #endif
  365 
  366 #endif /* _IP_DUMMYNET_H */

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