Linux-2.6.33.2/net/netfilter/ipvs/ip_vs_lblcr.c
/*
* IPVS: Locality-Based Least-Connection with Replication scheduler
*
* Authors: Wensong Zhang <wensong@gnuchina.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Changes:
* Julian Anastasov : Added the missing (dest->weight>0)
* condition in the ip_vs_dest_set_max.
*
*/
/*
* The lblc/r algorithm is as follows (pseudo code):
*
* if serverSet[dest_ip] is null then
* n, serverSet[dest_ip] <- {weighted least-conn node};
* else
* n <- {least-conn (alive) node in serverSet[dest_ip]};
* if (n is null) OR
* (n.conns>n.weight AND
* there is a node m with m.conns<m.weight/2) then
* n <- {weighted least-conn node};
* add n to serverSet[dest_ip];
* if |serverSet[dest_ip]| > 1 AND
* now - serverSet[dest_ip].lastMod > T then
* m <- {most conn node in serverSet[dest_ip]};
* remove m from serverSet[dest_ip];
* if serverSet[dest_ip] changed then
* serverSet[dest_ip].lastMod <- now;
*
* return n;
*
*/
#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/jiffies.h>
/* for sysctl */
#include <linux/fs.h>
#include <linux/sysctl.h>
#include <net/net_namespace.h>
#include <net/ip_vs.h>
/*
* It is for garbage collection of stale IPVS lblcr entries,
* when the table is full.
*/
#define CHECK_EXPIRE_INTERVAL (60*HZ)
#define ENTRY_TIMEOUT (6*60*HZ)
/*
* It is for full expiration check.
* When there is no partial expiration check (garbage collection)
* in a half hour, do a full expiration check to collect stale
* entries that haven't been touched for a day.
*/
#define COUNT_FOR_FULL_EXPIRATION 30
static int sysctl_ip_vs_lblcr_expiration = 24*60*60*HZ;
/*
* for IPVS lblcr entry hash table
*/
#ifndef CONFIG_IP_VS_LBLCR_TAB_BITS
#define CONFIG_IP_VS_LBLCR_TAB_BITS 10
#endif
#define IP_VS_LBLCR_TAB_BITS CONFIG_IP_VS_LBLCR_TAB_BITS
#define IP_VS_LBLCR_TAB_SIZE (1 << IP_VS_LBLCR_TAB_BITS)
#define IP_VS_LBLCR_TAB_MASK (IP_VS_LBLCR_TAB_SIZE - 1)
/*
* IPVS destination set structure and operations
*/
struct ip_vs_dest_list {
struct ip_vs_dest_list *next; /* list link */
struct ip_vs_dest *dest; /* destination server */
};
struct ip_vs_dest_set {
atomic_t size; /* set size */
unsigned long lastmod; /* last modified time */
struct ip_vs_dest_list *list; /* destination list */
rwlock_t lock; /* lock for this list */
};
static struct ip_vs_dest_list *
ip_vs_dest_set_insert(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
{
struct ip_vs_dest_list *e;
for (e=set->list; e!=NULL; e=e->next) {
if (e->dest == dest)
/* already existed */
return NULL;
}
e = kmalloc(sizeof(*e), GFP_ATOMIC);
if (e == NULL) {
pr_err("%s(): no memory\n", __func__);
return NULL;
}
atomic_inc(&dest->refcnt);
e->dest = dest;
/* link it to the list */
e->next = set->list;
set->list = e;
atomic_inc(&set->size);
set->lastmod = jiffies;
return e;
}
static void
ip_vs_dest_set_erase(struct ip_vs_dest_set *set, struct ip_vs_dest *dest)
{
struct ip_vs_dest_list *e, **ep;
for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
if (e->dest == dest) {
/* HIT */
*ep = e->next;
atomic_dec(&set->size);
set->lastmod = jiffies;
atomic_dec(&e->dest->refcnt);
kfree(e);
break;
}
ep = &e->next;
}
}
static void ip_vs_dest_set_eraseall(struct ip_vs_dest_set *set)
{
struct ip_vs_dest_list *e, **ep;
write_lock(&set->lock);
for (ep=&set->list, e=*ep; e!=NULL; e=*ep) {
*ep = e->next;
/*
* We don't kfree dest because it is refered either
* by its service or by the trash dest list.
*/
atomic_dec(&e->dest->refcnt);
kfree(e);
}
write_unlock(&set->lock);
}
/* get weighted least-connection node in the destination set */
static inline struct ip_vs_dest *ip_vs_dest_set_min(struct ip_vs_dest_set *set)
{
register struct ip_vs_dest_list *e;
struct ip_vs_dest *dest, *least;
int loh, doh;
if (set == NULL)
return NULL;
/* select the first destination server, whose weight > 0 */
for (e=set->list; e!=NULL; e=e->next) {
least = e->dest;
if (least->flags & IP_VS_DEST_F_OVERLOAD)
continue;
if ((atomic_read(&least->weight) > 0)
&& (least->flags & IP_VS_DEST_F_AVAILABLE)) {
loh = atomic_read(&least->activeconns) * 50
+ atomic_read(&least->inactconns);
goto nextstage;
}
}
return NULL;
/* find the destination with the weighted least load */
nextstage:
for (e=e->next; e!=NULL; e=e->next) {
dest = e->dest;
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
doh = atomic_read(&dest->activeconns) * 50
+ atomic_read(&dest->inactconns);
if ((loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight))
&& (dest->flags & IP_VS_DEST_F_AVAILABLE)) {
least = dest;
loh = doh;
}
}
IP_VS_DBG_BUF(6, "%s(): server %s:%d "
"activeconns %d refcnt %d weight %d overhead %d\n",
__func__,
IP_VS_DBG_ADDR(least->af, &least->addr),
ntohs(least->port),
atomic_read(&least->activeconns),
atomic_read(&least->refcnt),
atomic_read(&least->weight), loh);
return least;
}
/* get weighted most-connection node in the destination set */
static inline struct ip_vs_dest *ip_vs_dest_set_max(struct ip_vs_dest_set *set)
{
register struct ip_vs_dest_list *e;
struct ip_vs_dest *dest, *most;
int moh, doh;
if (set == NULL)
return NULL;
/* select the first destination server, whose weight > 0 */
for (e=set->list; e!=NULL; e=e->next) {
most = e->dest;
if (atomic_read(&most->weight) > 0) {
moh = atomic_read(&most->activeconns) * 50
+ atomic_read(&most->inactconns);
goto nextstage;
}
}
return NULL;
/* find the destination with the weighted most load */
nextstage:
for (e=e->next; e!=NULL; e=e->next) {
dest = e->dest;
doh = atomic_read(&dest->activeconns) * 50
+ atomic_read(&dest->inactconns);
/* moh/mw < doh/dw ==> moh*dw < doh*mw, where mw,dw>0 */
if ((moh * atomic_read(&dest->weight) <
doh * atomic_read(&most->weight))
&& (atomic_read(&dest->weight) > 0)) {
most = dest;
moh = doh;
}
}
IP_VS_DBG_BUF(6, "%s(): server %s:%d "
"activeconns %d refcnt %d weight %d overhead %d\n",
__func__,
IP_VS_DBG_ADDR(most->af, &most->addr), ntohs(most->port),
atomic_read(&most->activeconns),
atomic_read(&most->refcnt),
atomic_read(&most->weight), moh);
return most;
}
/*
* IPVS lblcr entry represents an association between destination
* IP address and its destination server set
*/
struct ip_vs_lblcr_entry {
struct list_head list;
int af; /* address family */
union nf_inet_addr addr; /* destination IP address */
struct ip_vs_dest_set set; /* destination server set */
unsigned long lastuse; /* last used time */
};
/*
* IPVS lblcr hash table
*/
struct ip_vs_lblcr_table {
struct list_head bucket[IP_VS_LBLCR_TAB_SIZE]; /* hash bucket */
atomic_t entries; /* number of entries */
int max_size; /* maximum size of entries */
struct timer_list periodic_timer; /* collect stale entries */
int rover; /* rover for expire check */
int counter; /* counter for no expire */
};
/*
* IPVS LBLCR sysctl table
*/
static ctl_table vs_vars_table[] = {
{
.procname = "lblcr_expiration",
.data = &sysctl_ip_vs_lblcr_expiration,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
{ }
};
static struct ctl_table_header * sysctl_header;
static inline void ip_vs_lblcr_free(struct ip_vs_lblcr_entry *en)
{
list_del(&en->list);
ip_vs_dest_set_eraseall(&en->set);
kfree(en);
}
/*
* Returns hash value for IPVS LBLCR entry
*/
static inline unsigned
ip_vs_lblcr_hashkey(int af, const union nf_inet_addr *addr)
{
__be32 addr_fold = addr->ip;
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6)
addr_fold = addr->ip6[0]^addr->ip6[1]^
addr->ip6[2]^addr->ip6[3];
#endif
return (ntohl(addr_fold)*2654435761UL) & IP_VS_LBLCR_TAB_MASK;
}
/*
* Hash an entry in the ip_vs_lblcr_table.
* returns bool success.
*/
static void
ip_vs_lblcr_hash(struct ip_vs_lblcr_table *tbl, struct ip_vs_lblcr_entry *en)
{
unsigned hash = ip_vs_lblcr_hashkey(en->af, &en->addr);
list_add(&en->list, &tbl->bucket[hash]);
atomic_inc(&tbl->entries);
}
/*
* Get ip_vs_lblcr_entry associated with supplied parameters. Called under
* read lock.
*/
static inline struct ip_vs_lblcr_entry *
ip_vs_lblcr_get(int af, struct ip_vs_lblcr_table *tbl,
const union nf_inet_addr *addr)
{
unsigned hash = ip_vs_lblcr_hashkey(af, addr);
struct ip_vs_lblcr_entry *en;
list_for_each_entry(en, &tbl->bucket[hash], list)
if (ip_vs_addr_equal(af, &en->addr, addr))
return en;
return NULL;
}
/*
* Create or update an ip_vs_lblcr_entry, which is a mapping of a destination
* IP address to a server. Called under write lock.
*/
static inline struct ip_vs_lblcr_entry *
ip_vs_lblcr_new(struct ip_vs_lblcr_table *tbl, const union nf_inet_addr *daddr,
struct ip_vs_dest *dest)
{
struct ip_vs_lblcr_entry *en;
en = ip_vs_lblcr_get(dest->af, tbl, daddr);
if (!en) {
en = kmalloc(sizeof(*en), GFP_ATOMIC);
if (!en) {
pr_err("%s(): no memory\n", __func__);
return NULL;
}
en->af = dest->af;
ip_vs_addr_copy(dest->af, &en->addr, daddr);
en->lastuse = jiffies;
/* initilize its dest set */
atomic_set(&(en->set.size), 0);
en->set.list = NULL;
rwlock_init(&en->set.lock);
ip_vs_lblcr_hash(tbl, en);
}
write_lock(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest);
write_unlock(&en->set.lock);
return en;
}
/*
* Flush all the entries of the specified table.
*/
static void ip_vs_lblcr_flush(struct ip_vs_lblcr_table *tbl)
{
int i;
struct ip_vs_lblcr_entry *en, *nxt;
/* No locking required, only called during cleanup. */
for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
ip_vs_lblcr_free(en);
}
}
}
static inline void ip_vs_lblcr_full_check(struct ip_vs_service *svc)
{
struct ip_vs_lblcr_table *tbl = svc->sched_data;
unsigned long now = jiffies;
int i, j;
struct ip_vs_lblcr_entry *en, *nxt;
for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
write_lock(&svc->sched_lock);
list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
if (time_after(en->lastuse+sysctl_ip_vs_lblcr_expiration,
now))
continue;
ip_vs_lblcr_free(en);
atomic_dec(&tbl->entries);
}
write_unlock(&svc->sched_lock);
}
tbl->rover = j;
}
/*
* Periodical timer handler for IPVS lblcr table
* It is used to collect stale entries when the number of entries
* exceeds the maximum size of the table.
*
* Fixme: we probably need more complicated algorithm to collect
* entries that have not been used for a long time even
* if the number of entries doesn't exceed the maximum size
* of the table.
* The full expiration check is for this purpose now.
*/
static void ip_vs_lblcr_check_expire(unsigned long data)
{
struct ip_vs_service *svc = (struct ip_vs_service *) data;
struct ip_vs_lblcr_table *tbl = svc->sched_data;
unsigned long now = jiffies;
int goal;
int i, j;
struct ip_vs_lblcr_entry *en, *nxt;
if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
/* do full expiration check */
ip_vs_lblcr_full_check(svc);
tbl->counter = 1;
goto out;
}
if (atomic_read(&tbl->entries) <= tbl->max_size) {
tbl->counter++;
goto out;
}
goal = (atomic_read(&tbl->entries) - tbl->max_size)*4/3;
if (goal > tbl->max_size/2)
goal = tbl->max_size/2;
for (i=0, j=tbl->rover; i<IP_VS_LBLCR_TAB_SIZE; i++) {
j = (j + 1) & IP_VS_LBLCR_TAB_MASK;
write_lock(&svc->sched_lock);
list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
if (time_before(now, en->lastuse+ENTRY_TIMEOUT))
continue;
ip_vs_lblcr_free(en);
atomic_dec(&tbl->entries);
goal--;
}
write_unlock(&svc->sched_lock);
if (goal <= 0)
break;
}
tbl->rover = j;
out:
mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
}
static int ip_vs_lblcr_init_svc(struct ip_vs_service *svc)
{
int i;
struct ip_vs_lblcr_table *tbl;
/*
* Allocate the ip_vs_lblcr_table for this service
*/
tbl = kmalloc(sizeof(*tbl), GFP_ATOMIC);
if (tbl == NULL) {
pr_err("%s(): no memory\n", __func__);
return -ENOMEM;
}
svc->sched_data = tbl;
IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) allocated for "
"current service\n", sizeof(*tbl));
/*
* Initialize the hash buckets
*/
for (i=0; i<IP_VS_LBLCR_TAB_SIZE; i++) {
INIT_LIST_HEAD(&tbl->bucket[i]);
}
tbl->max_size = IP_VS_LBLCR_TAB_SIZE*16;
tbl->rover = 0;
tbl->counter = 1;
/*
* Hook periodic timer for garbage collection
*/
setup_timer(&tbl->periodic_timer, ip_vs_lblcr_check_expire,
(unsigned long)svc);
mod_timer(&tbl->periodic_timer, jiffies + CHECK_EXPIRE_INTERVAL);
return 0;
}
static int ip_vs_lblcr_done_svc(struct ip_vs_service *svc)
{
struct ip_vs_lblcr_table *tbl = svc->sched_data;
/* remove periodic timer */
del_timer_sync(&tbl->periodic_timer);
/* got to clean up table entries here */
ip_vs_lblcr_flush(tbl);
/* release the table itself */
kfree(tbl);
IP_VS_DBG(6, "LBLCR hash table (memory=%Zdbytes) released\n",
sizeof(*tbl));
return 0;
}
static inline struct ip_vs_dest *
__ip_vs_lblcr_schedule(struct ip_vs_service *svc)
{
struct ip_vs_dest *dest, *least;
int loh, doh;
/*
* We think the overhead of processing active connections is fifty
* times higher than that of inactive connections in average. (This
* fifty times might not be accurate, we will change it later.) We
* use the following formula to estimate the overhead:
* dest->activeconns*50 + dest->inactconns
* and the load:
* (dest overhead) / dest->weight
*
* Remember -- no floats in kernel mode!!!
* The comparison of h1*w2 > h2*w1 is equivalent to that of
* h1/w1 > h2/w2
* if every weight is larger than zero.
*
* The server with weight=0 is quiesced and will not receive any
* new connection.
*/
list_for_each_entry(dest, &svc->destinations, n_list) {
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
if (atomic_read(&dest->weight) > 0) {
least = dest;
loh = atomic_read(&least->activeconns) * 50
+ atomic_read(&least->inactconns);
goto nextstage;
}
}
return NULL;
/*
* Find the destination with the least load.
*/
nextstage:
list_for_each_entry_continue(dest, &svc->destinations, n_list) {
if (dest->flags & IP_VS_DEST_F_OVERLOAD)
continue;
doh = atomic_read(&dest->activeconns) * 50
+ atomic_read(&dest->inactconns);
if (loh * atomic_read(&dest->weight) >
doh * atomic_read(&least->weight)) {
least = dest;
loh = doh;
}
}
IP_VS_DBG_BUF(6, "LBLCR: server %s:%d "
"activeconns %d refcnt %d weight %d overhead %d\n",
IP_VS_DBG_ADDR(least->af, &least->addr),
ntohs(least->port),
atomic_read(&least->activeconns),
atomic_read(&least->refcnt),
atomic_read(&least->weight), loh);
return least;
}
/*
* If this destination server is overloaded and there is a less loaded
* server, then return true.
*/
static inline int
is_overloaded(struct ip_vs_dest *dest, struct ip_vs_service *svc)
{
if (atomic_read(&dest->activeconns) > atomic_read(&dest->weight)) {
struct ip_vs_dest *d;
list_for_each_entry(d, &svc->destinations, n_list) {
if (atomic_read(&d->activeconns)*2
< atomic_read(&d->weight)) {
return 1;
}
}
}
return 0;
}
/*
* Locality-Based (weighted) Least-Connection scheduling
*/
static struct ip_vs_dest *
ip_vs_lblcr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
struct ip_vs_lblcr_table *tbl = svc->sched_data;
struct ip_vs_iphdr iph;
struct ip_vs_dest *dest = NULL;
struct ip_vs_lblcr_entry *en;
ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
/* First look in our cache */
read_lock(&svc->sched_lock);
en = ip_vs_lblcr_get(svc->af, tbl, &iph.daddr);
if (en) {
/* We only hold a read lock, but this is atomic */
en->lastuse = jiffies;
/* Get the least loaded destination */
read_lock(&en->set.lock);
dest = ip_vs_dest_set_min(&en->set);
read_unlock(&en->set.lock);
/* More than one destination + enough time passed by, cleanup */
if (atomic_read(&en->set.size) > 1 &&
time_after(jiffies, en->set.lastmod +
sysctl_ip_vs_lblcr_expiration)) {
struct ip_vs_dest *m;
write_lock(&en->set.lock);
m = ip_vs_dest_set_max(&en->set);
if (m)
ip_vs_dest_set_erase(&en->set, m);
write_unlock(&en->set.lock);
}
/* If the destination is not overloaded, use it */
if (dest && !is_overloaded(dest, svc)) {
read_unlock(&svc->sched_lock);
goto out;
}
/* The cache entry is invalid, time to schedule */
dest = __ip_vs_lblcr_schedule(svc);
if (!dest) {
IP_VS_ERR_RL("LBLCR: no destination available\n");
read_unlock(&svc->sched_lock);
return NULL;
}
/* Update our cache entry */
write_lock(&en->set.lock);
ip_vs_dest_set_insert(&en->set, dest);
write_unlock(&en->set.lock);
}
read_unlock(&svc->sched_lock);
if (dest)
goto out;
/* No cache entry, time to schedule */
dest = __ip_vs_lblcr_schedule(svc);
if (!dest) {
IP_VS_DBG(1, "no destination available\n");
return NULL;
}
/* If we fail to create a cache entry, we'll just use the valid dest */
write_lock(&svc->sched_lock);
ip_vs_lblcr_new(tbl, &iph.daddr, dest);
write_unlock(&svc->sched_lock);
out:
IP_VS_DBG_BUF(6, "LBLCR: destination IP address %s --> server %s:%d\n",
IP_VS_DBG_ADDR(svc->af, &iph.daddr),
IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port));
return dest;
}
/*
* IPVS LBLCR Scheduler structure
*/
static struct ip_vs_scheduler ip_vs_lblcr_scheduler =
{
.name = "lblcr",
.refcnt = ATOMIC_INIT(0),
.module = THIS_MODULE,
.n_list = LIST_HEAD_INIT(ip_vs_lblcr_scheduler.n_list),
.init_service = ip_vs_lblcr_init_svc,
.done_service = ip_vs_lblcr_done_svc,
.schedule = ip_vs_lblcr_schedule,
};
static int __init ip_vs_lblcr_init(void)
{
int ret;
sysctl_header = register_sysctl_paths(net_vs_ctl_path, vs_vars_table);
ret = register_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
if (ret)
unregister_sysctl_table(sysctl_header);
return ret;
}
static void __exit ip_vs_lblcr_cleanup(void)
{
unregister_sysctl_table(sysctl_header);
unregister_ip_vs_scheduler(&ip_vs_lblcr_scheduler);
}
module_init(ip_vs_lblcr_init);
module_exit(ip_vs_lblcr_cleanup);
MODULE_LICENSE("GPL");