897c0f57d4
2) Alter packet flow inside dummynet: allow certain packets to bypass
dummynet scheduler. Benefits are:
- lower latency: if packet flow does not exceed pipe bandwidth, packets
will not be (up to tick) delayed (due to dummynet's scheduler granularity).
- lower overhead: if packet avoids dummynet scheduler it shouldn't reenter ip
stack later. Such packets can be fastforwarded.
- recursion (which can lead to kernel stack exhaution) eliminated. This fix
long existed panic, which can be triggered this way:
kldload dummynet
sysctl net.inet.ip.fw.one_pass=0
ipfw pipe 1 config bw 0
for i in `jot 30`; do ipfw add 1 pipe 1 icmp from any to any; done
ping -c 1 localhost
3) Three new sysctl nodes are added:
net.inet.ip.dummynet.io_pkt - packets passed to dummynet
net.inet.ip.dummynet.io_pkt_fast - packets avoided dummynet scheduler
net.inet.ip.dummynet.io_pkt_drop - packets dropped by dummynet
P.S. Above comments are true only for layer 3 packets. Layer 2 packet flow
is not changed yet.
MFC after: 3 month
368 lines
14 KiB
C
368 lines
14 KiB
C
/*-
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* Copyright (c) 1998-2002 Luigi Rizzo, Universita` di Pisa
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* Portions Copyright (c) 2000 Akamba Corp.
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* All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _IP_DUMMYNET_H
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#define _IP_DUMMYNET_H
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/*
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* Definition of dummynet data structures. In the structures, I decided
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* not to use the macros in <sys/queue.h> in the hope of making the code
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* easier to port to other architectures. The type of lists and queue we
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* use here is pretty simple anyways.
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*/
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/*
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* We start with a heap, which is used in the scheduler to decide when
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* to transmit packets etc.
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*
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* The key for the heap is used for two different values:
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*
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* 1. timer ticks- max 10K/second, so 32 bits are enough;
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*
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* 2. virtual times. These increase in steps of len/x, where len is the
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* packet length, and x is either the weight of the flow, or the
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* sum of all weights.
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* If we limit to max 1000 flows and a max weight of 100, then
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* x needs 17 bits. The packet size is 16 bits, so we can easily
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* overflow if we do not allow errors.
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* So we use a key "dn_key" which is 64 bits. Some macros are used to
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* compare key values and handle wraparounds.
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* MAX64 returns the largest of two key values.
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* MY_M is used as a shift count when doing fixed point arithmetic
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* (a better name would be useful...).
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*/
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typedef u_int64_t dn_key ; /* sorting key */
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#define DN_KEY_LT(a,b) ((int64_t)((a)-(b)) < 0)
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#define DN_KEY_LEQ(a,b) ((int64_t)((a)-(b)) <= 0)
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#define DN_KEY_GT(a,b) ((int64_t)((a)-(b)) > 0)
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#define DN_KEY_GEQ(a,b) ((int64_t)((a)-(b)) >= 0)
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#define MAX64(x,y) (( (int64_t) ( (y)-(x) )) > 0 ) ? (y) : (x)
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#define MY_M 16 /* number of left shift to obtain a larger precision */
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/*
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* XXX With this scaling, max 1000 flows, max weight 100, 1Gbit/s, the
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* virtual time wraps every 15 days.
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*/
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/*
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* The maximum hash table size for queues. This value must be a power
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* of 2.
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*/
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#define DN_MAX_HASH_SIZE 65536
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/*
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* A heap entry is made of a key and a pointer to the actual
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* object stored in the heap.
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* The heap is an array of dn_heap_entry entries, dynamically allocated.
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* Current size is "size", with "elements" actually in use.
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* The heap normally supports only ordered insert and extract from the top.
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* If we want to extract an object from the middle of the heap, we
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* have to know where the object itself is located in the heap (or we
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* need to scan the whole array). To this purpose, an object has a
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* field (int) which contains the index of the object itself into the
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* heap. When the object is moved, the field must also be updated.
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* The offset of the index in the object is stored in the 'offset'
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* field in the heap descriptor. The assumption is that this offset
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* is non-zero if we want to support extract from the middle.
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*/
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struct dn_heap_entry {
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dn_key key ; /* sorting key. Topmost element is smallest one */
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void *object ; /* object pointer */
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} ;
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struct dn_heap {
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int size ;
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int elements ;
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int offset ; /* XXX if > 0 this is the offset of direct ptr to obj */
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struct dn_heap_entry *p ; /* really an array of "size" entries */
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} ;
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#ifdef _KERNEL
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/*
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* Packets processed by dummynet have an mbuf tag associated with
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* them that carries their dummynet state. This is used within
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* the dummynet code as well as outside when checking for special
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* processing requirements.
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*/
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struct dn_pkt_tag {
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struct ip_fw *rule; /* matching rule */
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int dn_dir; /* action when packet comes out. */
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#define DN_TO_IP_OUT 1
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#define DN_TO_IP_IN 2
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/* Obsolete: #define DN_TO_BDG_FWD 3 */
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#define DN_TO_ETH_DEMUX 4
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#define DN_TO_ETH_OUT 5
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#define DN_TO_IP6_IN 6
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#define DN_TO_IP6_OUT 7
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#define DN_TO_IFB_FWD 8
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dn_key output_time; /* when the pkt is due for delivery */
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struct ifnet *ifp; /* interface, for ip_output */
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struct _ip6dn_args ip6opt; /* XXX ipv6 options */
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};
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#endif /* _KERNEL */
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/*
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* Overall structure of dummynet (with WF2Q+):
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In dummynet, packets are selected with the firewall rules, and passed
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to two different objects: PIPE or QUEUE.
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A QUEUE is just a queue with configurable size and queue management
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policy. It is also associated with a mask (to discriminate among
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different flows), a weight (used to give different shares of the
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bandwidth to different flows) and a "pipe", which essentially
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supplies the transmit clock for all queues associated with that
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pipe.
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A PIPE emulates a fixed-bandwidth link, whose bandwidth is
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configurable. The "clock" for a pipe can come from either an
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internal timer, or from the transmit interrupt of an interface.
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A pipe is also associated with one (or more, if masks are used)
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queue, where all packets for that pipe are stored.
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The bandwidth available on the pipe is shared by the queues
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associated with that pipe (only one in case the packet is sent
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to a PIPE) according to the WF2Q+ scheduling algorithm and the
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configured weights.
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In general, incoming packets are stored in the appropriate queue,
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which is then placed into one of a few heaps managed by a scheduler
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to decide when the packet should be extracted.
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The scheduler (a function called dummynet()) is run at every timer
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tick, and grabs queues from the head of the heaps when they are
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ready for processing.
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There are three data structures definining a pipe and associated queues:
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+ dn_pipe, which contains the main configuration parameters related
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to delay and bandwidth;
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+ dn_flow_set, which contains WF2Q+ configuration, flow
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masks, plr and RED configuration;
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+ dn_flow_queue, which is the per-flow queue (containing the packets)
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Multiple dn_flow_set can be linked to the same pipe, and multiple
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dn_flow_queue can be linked to the same dn_flow_set.
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All data structures are linked in a linear list which is used for
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housekeeping purposes.
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During configuration, we create and initialize the dn_flow_set
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and dn_pipe structures (a dn_pipe also contains a dn_flow_set).
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At runtime: packets are sent to the appropriate dn_flow_set (either
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WFQ ones, or the one embedded in the dn_pipe for fixed-rate flows),
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which in turn dispatches them to the appropriate dn_flow_queue
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(created dynamically according to the masks).
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The transmit clock for fixed rate flows (ready_event()) selects the
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dn_flow_queue to be used to transmit the next packet. For WF2Q,
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wfq_ready_event() extract a pipe which in turn selects the right
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flow using a number of heaps defined into the pipe itself.
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*
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*/
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/*
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* per flow queue. This contains the flow identifier, the queue
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* of packets, counters, and parameters used to support both RED and
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* WF2Q+.
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*
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* A dn_flow_queue is created and initialized whenever a packet for
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* a new flow arrives.
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*/
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struct dn_flow_queue {
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struct dn_flow_queue *next ;
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struct ipfw_flow_id id ;
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struct mbuf *head, *tail ; /* queue of packets */
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u_int len ;
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u_int len_bytes ;
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u_long numbytes ; /* credit for transmission (dynamic queues) */
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u_int64_t tot_pkts ; /* statistics counters */
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u_int64_t tot_bytes ;
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u_int32_t drops ;
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int hash_slot ; /* debugging/diagnostic */
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/* RED parameters */
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int avg ; /* average queue length est. (scaled) */
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int count ; /* arrivals since last RED drop */
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int random ; /* random value (scaled) */
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u_int32_t q_time ; /* start of queue idle time */
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/* WF2Q+ support */
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struct dn_flow_set *fs ; /* parent flow set */
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int heap_pos ; /* position (index) of struct in heap */
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dn_key sched_time ; /* current time when queue enters ready_heap */
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dn_key S,F ; /* start time, finish time */
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/*
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* Setting F < S means the timestamp is invalid. We only need
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* to test this when the queue is empty.
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*/
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} ;
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/*
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* flow_set descriptor. Contains the "template" parameters for the
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* queue configuration, and pointers to the hash table of dn_flow_queue's.
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*
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* The hash table is an array of lists -- we identify the slot by
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* hashing the flow-id, then scan the list looking for a match.
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* The size of the hash table (buckets) is configurable on a per-queue
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* basis.
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*
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* A dn_flow_set is created whenever a new queue or pipe is created (in the
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* latter case, the structure is located inside the struct dn_pipe).
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*/
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struct dn_flow_set {
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SLIST_ENTRY(dn_flow_set) next; /* linked list in a hash slot */
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u_short fs_nr ; /* flow_set number */
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u_short flags_fs;
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#define DN_HAVE_FLOW_MASK 0x0001
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#define DN_IS_RED 0x0002
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#define DN_IS_GENTLE_RED 0x0004
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#define DN_QSIZE_IS_BYTES 0x0008 /* queue size is measured in bytes */
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#define DN_NOERROR 0x0010 /* do not report ENOBUFS on drops */
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#define DN_IS_PIPE 0x4000
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#define DN_IS_QUEUE 0x8000
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struct dn_pipe *pipe ; /* pointer to parent pipe */
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u_short parent_nr ; /* parent pipe#, 0 if local to a pipe */
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int weight ; /* WFQ queue weight */
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int qsize ; /* queue size in slots or bytes */
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int plr ; /* pkt loss rate (2^31-1 means 100%) */
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struct ipfw_flow_id flow_mask ;
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/* hash table of queues onto this flow_set */
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int rq_size ; /* number of slots */
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int rq_elements ; /* active elements */
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struct dn_flow_queue **rq; /* array of rq_size entries */
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u_int32_t last_expired ; /* do not expire too frequently */
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int backlogged ; /* #active queues for this flowset */
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/* RED parameters */
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#define SCALE_RED 16
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#define SCALE(x) ( (x) << SCALE_RED )
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#define SCALE_VAL(x) ( (x) >> SCALE_RED )
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#define SCALE_MUL(x,y) ( ( (x) * (y) ) >> SCALE_RED )
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int w_q ; /* queue weight (scaled) */
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int max_th ; /* maximum threshold for queue (scaled) */
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int min_th ; /* minimum threshold for queue (scaled) */
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int max_p ; /* maximum value for p_b (scaled) */
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u_int c_1 ; /* max_p/(max_th-min_th) (scaled) */
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u_int c_2 ; /* max_p*min_th/(max_th-min_th) (scaled) */
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u_int c_3 ; /* for GRED, (1-max_p)/max_th (scaled) */
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u_int c_4 ; /* for GRED, 1 - 2*max_p (scaled) */
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u_int * w_q_lookup ; /* lookup table for computing (1-w_q)^t */
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u_int lookup_depth ; /* depth of lookup table */
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int lookup_step ; /* granularity inside the lookup table */
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int lookup_weight ; /* equal to (1-w_q)^t / (1-w_q)^(t+1) */
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int avg_pkt_size ; /* medium packet size */
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int max_pkt_size ; /* max packet size */
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};
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SLIST_HEAD(dn_flow_set_head, dn_flow_set);
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/*
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* Pipe descriptor. Contains global parameters, delay-line queue,
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* and the flow_set used for fixed-rate queues.
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*
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* For WF2Q+ support it also has 3 heaps holding dn_flow_queue:
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* not_eligible_heap, for queues whose start time is higher
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* than the virtual time. Sorted by start time.
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* scheduler_heap, for queues eligible for scheduling. Sorted by
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* finish time.
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* idle_heap, all flows that are idle and can be removed. We
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* do that on each tick so we do not slow down too much
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* operations during forwarding.
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*
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*/
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struct dn_pipe { /* a pipe */
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SLIST_ENTRY(dn_pipe) next; /* linked list in a hash slot */
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int pipe_nr ; /* number */
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int bandwidth; /* really, bytes/tick. */
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int delay ; /* really, ticks */
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struct mbuf *head, *tail ; /* packets in delay line */
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/* WF2Q+ */
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struct dn_heap scheduler_heap ; /* top extract - key Finish time*/
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struct dn_heap not_eligible_heap; /* top extract- key Start time */
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struct dn_heap idle_heap ; /* random extract - key Start=Finish time */
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dn_key V ; /* virtual time */
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int sum; /* sum of weights of all active sessions */
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int numbytes; /* bits I can transmit (more or less). */
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dn_key sched_time ; /* time pipe was scheduled in ready_heap */
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/*
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* When the tx clock come from an interface (if_name[0] != '\0'), its name
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* is stored below, whereas the ifp is filled when the rule is configured.
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*/
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char if_name[IFNAMSIZ];
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struct ifnet *ifp ;
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int ready ; /* set if ifp != NULL and we got a signal from it */
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struct dn_flow_set fs ; /* used with fixed-rate flows */
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};
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SLIST_HEAD(dn_pipe_head, dn_pipe);
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#ifdef _KERNEL
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typedef int ip_dn_ctl_t(struct sockopt *); /* raw_ip.c */
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typedef void ip_dn_ruledel_t(void *); /* ip_fw.c */
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typedef int ip_dn_io_t(struct mbuf **m, int dir, struct ip_fw_args *fwa);
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extern ip_dn_ctl_t *ip_dn_ctl_ptr;
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extern ip_dn_ruledel_t *ip_dn_ruledel_ptr;
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extern ip_dn_io_t *ip_dn_io_ptr;
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#define DUMMYNET_LOADED (ip_dn_io_ptr != NULL)
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/*
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* Return the IPFW rule associated with the dummynet tag; if any.
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* Make sure that the dummynet tag is not reused by lower layers.
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*/
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static __inline struct ip_fw *
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ip_dn_claim_rule(struct mbuf *m)
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{
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struct m_tag *mtag = m_tag_find(m, PACKET_TAG_DUMMYNET, NULL);
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if (mtag != NULL) {
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mtag->m_tag_id = PACKET_TAG_NONE;
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return (((struct dn_pkt_tag *)(mtag+1))->rule);
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} else
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return (NULL);
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}
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#endif
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#endif /* _IP_DUMMYNET_H */
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