/usr/src/openvswitch-1.4.0/ofproto/pinsched.c is in openvswitch-datapath-dkms 1.4.0-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "pinsched.h"
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdint.h>
#include <stdlib.h>
#include "hash.h"
#include "hmap.h"
#include "ofpbuf.h"
#include "openflow/openflow.h"
#include "poll-loop.h"
#include "random.h"
#include "rconn.h"
#include "timeval.h"
#include "vconn.h"
struct pinqueue {
struct hmap_node node; /* In struct pinsched's 'queues' hmap. */
uint16_t port_no; /* Port number. */
struct list packets; /* Contains "struct ofpbuf"s. */
int n; /* Number of packets in 'packets'. */
};
struct pinsched {
/* Client-supplied parameters. */
int rate_limit; /* Packets added to bucket per second. */
int burst_limit; /* Maximum token bucket size, in packets. */
/* One queue per physical port. */
struct hmap queues; /* Contains "struct pinqueue"s. */
int n_queued; /* Sum over queues[*].n. */
struct pinqueue *next_txq; /* Next pinqueue check in round-robin. */
/* Token bucket.
*
* It costs 1000 tokens to send a single packet_in message. A single token
* per message would be more straightforward, but this choice lets us avoid
* round-off error in refill_bucket()'s calculation of how many tokens to
* add to the bucket, since no division step is needed. */
long long int last_fill; /* Time at which we last added tokens. */
int tokens; /* Current number of tokens. */
/* Transmission queue. */
int n_txq; /* No. of packets waiting in rconn for tx. */
/* Statistics reporting. */
unsigned long long n_normal; /* # txed w/o rate limit queuing. */
unsigned long long n_limited; /* # queued for rate limiting. */
unsigned long long n_queue_dropped; /* # dropped due to queue overflow. */
};
static void
advance_txq(struct pinsched *ps)
{
struct hmap_node *next;
next = (ps->next_txq
? hmap_next(&ps->queues, &ps->next_txq->node)
: hmap_first(&ps->queues));
ps->next_txq = next ? CONTAINER_OF(next, struct pinqueue, node) : NULL;
}
static struct ofpbuf *
dequeue_packet(struct pinsched *ps, struct pinqueue *q)
{
struct ofpbuf *packet = ofpbuf_from_list(list_pop_front(&q->packets));
q->n--;
ps->n_queued--;
return packet;
}
/* Destroys 'q' and removes it from 'ps''s set of queues.
* (The caller must ensure that 'q' is empty.) */
static void
pinqueue_destroy(struct pinsched *ps, struct pinqueue *q)
{
hmap_remove(&ps->queues, &q->node);
free(q);
}
static struct pinqueue *
pinqueue_get(struct pinsched *ps, uint16_t port_no)
{
uint32_t hash = hash_int(port_no, 0);
struct pinqueue *q;
HMAP_FOR_EACH_IN_BUCKET (q, node, hash, &ps->queues) {
if (port_no == q->port_no) {
return q;
}
}
q = xmalloc(sizeof *q);
hmap_insert(&ps->queues, &q->node, hash);
q->port_no = port_no;
list_init(&q->packets);
q->n = 0;
return q;
}
/* Drop a packet from the longest queue in 'ps'. */
static void
drop_packet(struct pinsched *ps)
{
struct pinqueue *longest; /* Queue currently selected as longest. */
int n_longest = 0; /* # of queues of same length as 'longest'. */
struct pinqueue *q;
ps->n_queue_dropped++;
longest = NULL;
HMAP_FOR_EACH (q, node, &ps->queues) {
if (!longest || longest->n < q->n) {
longest = q;
n_longest = 1;
} else if (longest->n == q->n) {
n_longest++;
/* Randomly select one of the longest queues, with a uniform
* distribution (Knuth algorithm 3.4.2R). */
if (!random_range(n_longest)) {
longest = q;
}
}
}
/* FIXME: do we want to pop the tail instead? */
ofpbuf_delete(dequeue_packet(ps, longest));
if (longest->n == 0) {
pinqueue_destroy(ps, longest);
}
}
/* Remove and return the next packet to transmit (in round-robin order). */
static struct ofpbuf *
get_tx_packet(struct pinsched *ps)
{
struct ofpbuf *packet;
struct pinqueue *q;
if (!ps->next_txq) {
advance_txq(ps);
}
q = ps->next_txq;
packet = dequeue_packet(ps, q);
advance_txq(ps);
if (q->n == 0) {
pinqueue_destroy(ps, q);
}
return packet;
}
/* Add tokens to the bucket based on elapsed time. */
static void
refill_bucket(struct pinsched *ps)
{
long long int now = time_msec();
long long int tokens = (now - ps->last_fill) * ps->rate_limit + ps->tokens;
if (tokens >= 1000) {
ps->last_fill = now;
ps->tokens = MIN(tokens, ps->burst_limit * 1000);
}
}
/* Attempts to remove enough tokens from 'ps' to transmit a packet. Returns
* true if successful, false otherwise. (In the latter case no tokens are
* removed.) */
static bool
get_token(struct pinsched *ps)
{
if (ps->tokens >= 1000) {
ps->tokens -= 1000;
return true;
} else {
return false;
}
}
void
pinsched_send(struct pinsched *ps, uint16_t port_no,
struct ofpbuf *packet, pinsched_tx_cb *cb, void *aux)
{
if (!ps) {
cb(packet, aux);
} else if (!ps->n_queued && get_token(ps)) {
/* In the common case where we are not constrained by the rate limit,
* let the packet take the normal path. */
ps->n_normal++;
cb(packet, aux);
} else {
/* Otherwise queue it up for the periodic callback to drain out. */
struct pinqueue *q;
/* We might be called with a buffer obtained from dpif_recv() that has
* much more allocated space than actual content most of the time.
* Since we're going to store the packet for some time, free up that
* otherwise wasted space. */
ofpbuf_trim(packet);
if (ps->n_queued >= ps->burst_limit) {
drop_packet(ps);
}
q = pinqueue_get(ps, port_no);
list_push_back(&q->packets, &packet->list_node);
q->n++;
ps->n_queued++;
ps->n_limited++;
}
}
void
pinsched_run(struct pinsched *ps, pinsched_tx_cb *cb, void *aux)
{
if (ps) {
int i;
/* Drain some packets out of the bucket if possible, but limit the
* number of iterations to allow other code to get work done too. */
refill_bucket(ps);
for (i = 0; ps->n_queued && get_token(ps) && i < 50; i++) {
cb(get_tx_packet(ps), aux);
}
}
}
void
pinsched_wait(struct pinsched *ps)
{
if (ps && ps->n_queued) {
if (ps->tokens >= 1000) {
/* We can transmit more packets as soon as we're called again. */
poll_immediate_wake();
} else {
/* We have to wait for the bucket to re-fill. We could calculate
* the exact amount of time here for increased smoothness. */
poll_timer_wait(TIME_UPDATE_INTERVAL / 2);
}
}
}
/* Creates and returns a scheduler for sending packet-in messages. */
struct pinsched *
pinsched_create(int rate_limit, int burst_limit)
{
struct pinsched *ps;
ps = xzalloc(sizeof *ps);
hmap_init(&ps->queues);
ps->n_queued = 0;
ps->next_txq = NULL;
ps->last_fill = time_msec();
ps->tokens = rate_limit * 100;
ps->n_txq = 0;
ps->n_normal = 0;
ps->n_limited = 0;
ps->n_queue_dropped = 0;
pinsched_set_limits(ps, rate_limit, burst_limit);
return ps;
}
void
pinsched_destroy(struct pinsched *ps)
{
if (ps) {
struct pinqueue *q, *next;
HMAP_FOR_EACH_SAFE (q, next, node, &ps->queues) {
hmap_remove(&ps->queues, &q->node);
ofpbuf_list_delete(&q->packets);
free(q);
}
hmap_destroy(&ps->queues);
free(ps);
}
}
void
pinsched_get_limits(const struct pinsched *ps,
int *rate_limit, int *burst_limit)
{
*rate_limit = ps->rate_limit;
*burst_limit = ps->burst_limit;
}
void
pinsched_set_limits(struct pinsched *ps, int rate_limit, int burst_limit)
{
if (rate_limit <= 0) {
rate_limit = 1000;
}
if (burst_limit <= 0) {
burst_limit = rate_limit / 4;
}
burst_limit = MAX(burst_limit, 1);
burst_limit = MIN(burst_limit, INT_MAX / 1000);
ps->rate_limit = rate_limit;
ps->burst_limit = burst_limit;
while (ps->n_queued > burst_limit) {
drop_packet(ps);
}
}
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