The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  * $FreeBSD$
   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 #ifdef _KERNEL
  113 /*
  114  * Packets processed by dummynet have an mbuf tag associated with
  115  * them that carries their dummynet state.  This is used within
  116  * the dummynet code as well as outside when checking for special
  117  * processing requirements.
  118  */
  119 struct dn_pkt_tag {
  120     struct ip_fw *rule;         /* matching rule */
  121     int dn_dir;                 /* action when packet comes out. */
  122 #define DN_TO_IP_OUT    1
  123 #define DN_TO_IP_IN     2
  124 #define DN_TO_BDG_FWD   3
  125 #define DN_TO_ETH_DEMUX 4
  126 #define DN_TO_ETH_OUT   5
  127 /* Reserved for DN_TO_IP6_IN, DN_TO_IP6_OUT */
  128 #define DN_TO_IFB_FWD   8
  129 
  130     dn_key output_time;         /* when the pkt is due for delivery     */
  131     struct ifnet *ifp;          /* interface, for ip_output             */
  132 };
  133 #endif /* _KERNEL */
  134 
  135 /*
  136  * Overall structure of dummynet (with WF2Q+):
  137 
  138 In dummynet, packets are selected with the firewall rules, and passed
  139 to two different objects: PIPE or QUEUE.
  140 
  141 A QUEUE is just a queue with configurable size and queue management
  142 policy. It is also associated with a mask (to discriminate among
  143 different flows), a weight (used to give different shares of the
  144 bandwidth to different flows) and a "pipe", which essentially
  145 supplies the transmit clock for all queues associated with that
  146 pipe.
  147 
  148 A PIPE emulates a fixed-bandwidth link, whose bandwidth is
  149 configurable.  The "clock" for a pipe can come from either an
  150 internal timer, or from the transmit interrupt of an interface.
  151 A pipe is also associated with one (or more, if masks are used)
  152 queue, where all packets for that pipe are stored.
  153 
  154 The bandwidth available on the pipe is shared by the queues
  155 associated with that pipe (only one in case the packet is sent
  156 to a PIPE) according to the WF2Q+ scheduling algorithm and the
  157 configured weights.
  158 
  159 In general, incoming packets are stored in the appropriate queue,
  160 which is then placed into one of a few heaps managed by a scheduler
  161 to decide when the packet should be extracted.
  162 The scheduler (a function called dummynet()) is run at every timer
  163 tick, and grabs queues from the head of the heaps when they are
  164 ready for processing.
  165 
  166 There are three data structures definining a pipe and associated queues:
  167 
  168  + dn_pipe, which contains the main configuration parameters related
  169    to delay and bandwidth;
  170  + dn_flow_set, which contains WF2Q+ configuration, flow
  171    masks, plr and RED configuration;
  172  + dn_flow_queue, which is the per-flow queue (containing the packets)
  173 
  174 Multiple dn_flow_set can be linked to the same pipe, and multiple
  175 dn_flow_queue can be linked to the same dn_flow_set.
  176 All data structures are linked in a linear list which is used for
  177 housekeeping purposes.
  178 
  179 During configuration, we create and initialize the dn_flow_set
  180 and dn_pipe structures (a dn_pipe also contains a dn_flow_set).
  181 
  182 At runtime: packets are sent to the appropriate dn_flow_set (either
  183 WFQ ones, or the one embedded in the dn_pipe for fixed-rate flows),
  184 which in turn dispatches them to the appropriate dn_flow_queue
  185 (created dynamically according to the masks).
  186 
  187 The transmit clock for fixed rate flows (ready_event()) selects the
  188 dn_flow_queue to be used to transmit the next packet. For WF2Q,
  189 wfq_ready_event() extract a pipe which in turn selects the right
  190 flow using a number of heaps defined into the pipe itself.
  191 
  192  *
  193  */
  194 
  195 /*
  196  * per flow queue. This contains the flow identifier, the queue
  197  * of packets, counters, and parameters used to support both RED and
  198  * WF2Q+.
  199  *
  200  * A dn_flow_queue is created and initialized whenever a packet for
  201  * a new flow arrives.
  202  */
  203 struct dn_flow_queue {
  204     struct dn_flow_queue *next ;
  205     struct ipfw_flow_id id ;
  206 
  207     struct mbuf *head, *tail ;  /* queue of packets */
  208     u_int len ;
  209     u_int len_bytes ;
  210     u_long numbytes ;           /* credit for transmission (dynamic queues) */
  211 
  212     u_int64_t tot_pkts ;        /* statistics counters  */
  213     u_int64_t tot_bytes ;
  214     u_int32_t drops ;
  215 
  216     int hash_slot ;             /* debugging/diagnostic */
  217 
  218     /* RED parameters */
  219     int avg ;                   /* average queue length est. (scaled) */
  220     int count ;                 /* arrivals since last RED drop */
  221     int random ;                /* random value (scaled) */
  222     u_int32_t q_time ;          /* start of queue idle time */
  223 
  224     /* WF2Q+ support */
  225     struct dn_flow_set *fs ;    /* parent flow set */
  226     int heap_pos ;              /* position (index) of struct in heap */
  227     dn_key sched_time ;         /* current time when queue enters ready_heap */
  228 
  229     dn_key S,F ;                /* start time, finish time */
  230     /*
  231      * Setting F < S means the timestamp is invalid. We only need
  232      * to test this when the queue is empty.
  233      */
  234 } ;
  235 
  236 /*
  237  * flow_set descriptor. Contains the "template" parameters for the
  238  * queue configuration, and pointers to the hash table of dn_flow_queue's.
  239  *
  240  * The hash table is an array of lists -- we identify the slot by
  241  * hashing the flow-id, then scan the list looking for a match.
  242  * The size of the hash table (buckets) is configurable on a per-queue
  243  * basis.
  244  *
  245  * A dn_flow_set is created whenever a new queue or pipe is created (in the
  246  * latter case, the structure is located inside the struct dn_pipe).
  247  */
  248 struct dn_flow_set {
  249     struct dn_flow_set *next; /* next flow set in all_flow_sets list */
  250 
  251     u_short fs_nr ;             /* flow_set number       */
  252     u_short flags_fs;
  253 #define DN_HAVE_FLOW_MASK       0x0001
  254 #define DN_IS_RED               0x0002
  255 #define DN_IS_GENTLE_RED        0x0004
  256 #define DN_QSIZE_IS_BYTES       0x0008  /* queue size is measured in bytes */
  257 #define DN_NOERROR              0x0010  /* do not report ENOBUFS on drops  */
  258 #define DN_IS_PIPE              0x4000
  259 #define DN_IS_QUEUE             0x8000
  260 
  261     struct dn_pipe *pipe ;      /* pointer to parent pipe */
  262     u_short parent_nr ;         /* parent pipe#, 0 if local to a pipe */
  263 
  264     int weight ;                /* WFQ queue weight */
  265     int qsize ;                 /* queue size in slots or bytes */
  266     int plr ;                   /* pkt loss rate (2^31-1 means 100%) */
  267 
  268     struct ipfw_flow_id flow_mask ;
  269 
  270     /* hash table of queues onto this flow_set */
  271     int rq_size ;               /* number of slots */
  272     int rq_elements ;           /* active elements */
  273     struct dn_flow_queue **rq;  /* array of rq_size entries */
  274 
  275     u_int32_t last_expired ;    /* do not expire too frequently */
  276     int backlogged ;            /* #active queues for this flowset */
  277 
  278         /* RED parameters */
  279 #define SCALE_RED               16
  280 #define SCALE(x)                ( (x) << SCALE_RED )
  281 #define SCALE_VAL(x)            ( (x) >> SCALE_RED )
  282 #define SCALE_MUL(x,y)          ( ( (x) * (y) ) >> SCALE_RED )
  283     int w_q ;                   /* queue weight (scaled) */
  284     int max_th ;                /* maximum threshold for queue (scaled) */
  285     int min_th ;                /* minimum threshold for queue (scaled) */
  286     int max_p ;                 /* maximum value for p_b (scaled) */
  287     u_int c_1 ;                 /* max_p/(max_th-min_th) (scaled) */
  288     u_int c_2 ;                 /* max_p*min_th/(max_th-min_th) (scaled) */
  289     u_int c_3 ;                 /* for GRED, (1-max_p)/max_th (scaled) */
  290     u_int c_4 ;                 /* for GRED, 1 - 2*max_p (scaled) */
  291     u_int * w_q_lookup ;        /* lookup table for computing (1-w_q)^t */
  292     u_int lookup_depth ;        /* depth of lookup table */
  293     int lookup_step ;           /* granularity inside the lookup table */
  294     int lookup_weight ;         /* equal to (1-w_q)^t / (1-w_q)^(t+1) */
  295     int avg_pkt_size ;          /* medium packet size */
  296     int max_pkt_size ;          /* max packet size */
  297 } ;
  298 
  299 /*
  300  * Pipe descriptor. Contains global parameters, delay-line queue,
  301  * and the flow_set used for fixed-rate queues.
  302  *
  303  * For WF2Q+ support it also has 3 heaps holding dn_flow_queue:
  304  *   not_eligible_heap, for queues whose start time is higher
  305  *      than the virtual time. Sorted by start time.
  306  *   scheduler_heap, for queues eligible for scheduling. Sorted by
  307  *      finish time.
  308  *   idle_heap, all flows that are idle and can be removed. We
  309  *      do that on each tick so we do not slow down too much
  310  *      operations during forwarding.
  311  *
  312  */
  313 struct dn_pipe {                /* a pipe */
  314     struct dn_pipe *next ;
  315 
  316     int pipe_nr ;               /* number       */
  317     int bandwidth;              /* really, bytes/tick.  */
  318     int delay ;                 /* really, ticks        */
  319 
  320     struct      mbuf *head, *tail ;     /* packets in delay line */
  321 
  322     /* WF2Q+ */
  323     struct dn_heap scheduler_heap ; /* top extract - key Finish time*/
  324     struct dn_heap not_eligible_heap; /* top extract- key Start time */
  325     struct dn_heap idle_heap ; /* random extract - key Start=Finish time */
  326 
  327     dn_key V ;                  /* virtual time */
  328     int sum;                    /* sum of weights of all active sessions */
  329     int numbytes;               /* bits I can transmit (more or less). */
  330 
  331     dn_key sched_time ;         /* time pipe was scheduled in ready_heap */
  332 
  333     /*
  334      * When the tx clock come from an interface (if_name[0] != '\0'), its name
  335      * is stored below, whereas the ifp is filled when the rule is configured.
  336      */
  337     char if_name[IFNAMSIZ];
  338     struct ifnet *ifp ;
  339     int ready ; /* set if ifp != NULL and we got a signal from it */
  340 
  341     struct dn_flow_set fs ; /* used with fixed-rate flows */
  342 };
  343 
  344 #ifdef _KERNEL
  345 typedef int ip_dn_ctl_t(struct sockopt *); /* raw_ip.c */
  346 typedef void ip_dn_ruledel_t(void *); /* ip_fw.c */
  347 typedef int ip_dn_io_t(struct mbuf *m, int pipe_nr, int dir,
  348         struct ip_fw_args *fwa);
  349 extern  ip_dn_ctl_t *ip_dn_ctl_ptr;
  350 extern  ip_dn_ruledel_t *ip_dn_ruledel_ptr;
  351 extern  ip_dn_io_t *ip_dn_io_ptr;
  352 #define DUMMYNET_LOADED (ip_dn_io_ptr != NULL)
  353 
  354 /*
  355  * Return the IPFW rule associated with the dummynet tag; if any.
  356  * Make sure that the dummynet tag is not reused by lower layers.
  357  */
  358 static __inline struct ip_fw *
  359 ip_dn_claim_rule(struct mbuf *m)
  360 {
  361         struct m_tag *mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
  362         if (mtag != NULL) {
  363                 mtag->m_tag_id = PACKET_TAG_NONE;
  364                 return (((struct dn_pkt_tag *)(mtag+1))->rule);
  365         } else
  366                 return (NULL);
  367 }
  368 #endif
  369 #endif /* _IP_DUMMYNET_H */

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