kernel-ark/net/ipv4/ipvs/ip_vs_lblc.c
Arnaldo Carvalho de Melo 14c850212e [INET_SOCK]: Move struct inet_sock & helper functions to net/inet_sock.h
To help in reducing the number of include dependencies, several files were
touched as they were getting needed headers indirectly for stuff they use.

Thanks also to Alan Menegotto for pointing out that net/dccp/proto.c had
linux/dccp.h include twice.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-03 13:11:21 -08:00

600 lines
14 KiB
C

/*
* IPVS: Locality-Based Least-Connection scheduling module
*
* Version: $Id: ip_vs_lblc.c,v 1.10 2002/09/15 08:14:08 wensong Exp $
*
* 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:
* Martin Hamilton : fixed the terrible locking bugs
* *lock(tbl->lock) ==> *lock(&tbl->lock)
* Wensong Zhang : fixed the uninitilized tbl->lock bug
* Wensong Zhang : added doing full expiration check to
* collect stale entries of 24+ hours when
* no partial expire check in a half hour
* Julian Anastasov : replaced del_timer call with del_timer_sync
* to avoid the possible race between timer
* handler and del_timer thread in SMP
*
*/
/*
* The lblc algorithm is as follows (pseudo code):
*
* if cachenode[dest_ip] is null then
* n, cachenode[dest_ip] <- {weighted least-conn node};
* else
* n <- cachenode[dest_ip];
* if (n is dead) OR
* (n.conns>n.weight AND
* there is a node m with m.conns<m.weight/2) then
* n, cachenode[dest_ip] <- {weighted least-conn node};
*
* return n;
*
* Thanks must go to Wenzhuo Zhang for talking WCCP to me and pushing
* me to write this module.
*/
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
/* for sysctl */
#include <linux/fs.h>
#include <linux/sysctl.h>
#include <net/ip_vs.h>
/*
* It is for garbage collection of stale IPVS lblc 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_lblc_expiration = 24*60*60*HZ;
/*
* for IPVS lblc entry hash table
*/
#ifndef CONFIG_IP_VS_LBLC_TAB_BITS
#define CONFIG_IP_VS_LBLC_TAB_BITS 10
#endif
#define IP_VS_LBLC_TAB_BITS CONFIG_IP_VS_LBLC_TAB_BITS
#define IP_VS_LBLC_TAB_SIZE (1 << IP_VS_LBLC_TAB_BITS)
#define IP_VS_LBLC_TAB_MASK (IP_VS_LBLC_TAB_SIZE - 1)
/*
* IPVS lblc entry represents an association between destination
* IP address and its destination server
*/
struct ip_vs_lblc_entry {
struct list_head list;
__u32 addr; /* destination IP address */
struct ip_vs_dest *dest; /* real server (cache) */
unsigned long lastuse; /* last used time */
};
/*
* IPVS lblc hash table
*/
struct ip_vs_lblc_table {
rwlock_t lock; /* lock for this table */
struct list_head bucket[IP_VS_LBLC_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 LBLC sysctl table
*/
static ctl_table vs_vars_table[] = {
{
.ctl_name = NET_IPV4_VS_LBLC_EXPIRE,
.procname = "lblc_expiration",
.data = &sysctl_ip_vs_lblc_expiration,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_jiffies,
},
{ .ctl_name = 0 }
};
static ctl_table vs_table[] = {
{
.ctl_name = NET_IPV4_VS,
.procname = "vs",
.mode = 0555,
.child = vs_vars_table
},
{ .ctl_name = 0 }
};
static ctl_table ipvs_ipv4_table[] = {
{
.ctl_name = NET_IPV4,
.procname = "ipv4",
.mode = 0555,
.child = vs_table
},
{ .ctl_name = 0 }
};
static ctl_table lblc_root_table[] = {
{
.ctl_name = CTL_NET,
.procname = "net",
.mode = 0555,
.child = ipvs_ipv4_table
},
{ .ctl_name = 0 }
};
static struct ctl_table_header * sysctl_header;
/*
* new/free a ip_vs_lblc_entry, which is a mapping of a destionation
* IP address to a server.
*/
static inline struct ip_vs_lblc_entry *
ip_vs_lblc_new(__u32 daddr, struct ip_vs_dest *dest)
{
struct ip_vs_lblc_entry *en;
en = kmalloc(sizeof(struct ip_vs_lblc_entry), GFP_ATOMIC);
if (en == NULL) {
IP_VS_ERR("ip_vs_lblc_new(): no memory\n");
return NULL;
}
INIT_LIST_HEAD(&en->list);
en->addr = daddr;
atomic_inc(&dest->refcnt);
en->dest = dest;
return en;
}
static inline void ip_vs_lblc_free(struct ip_vs_lblc_entry *en)
{
list_del(&en->list);
/*
* We don't kfree dest because it is refered either by its service
* or the trash dest list.
*/
atomic_dec(&en->dest->refcnt);
kfree(en);
}
/*
* Returns hash value for IPVS LBLC entry
*/
static inline unsigned ip_vs_lblc_hashkey(__u32 addr)
{
return (ntohl(addr)*2654435761UL) & IP_VS_LBLC_TAB_MASK;
}
/*
* Hash an entry in the ip_vs_lblc_table.
* returns bool success.
*/
static int
ip_vs_lblc_hash(struct ip_vs_lblc_table *tbl, struct ip_vs_lblc_entry *en)
{
unsigned hash;
if (!list_empty(&en->list)) {
IP_VS_ERR("ip_vs_lblc_hash(): request for already hashed, "
"called from %p\n", __builtin_return_address(0));
return 0;
}
/*
* Hash by destination IP address
*/
hash = ip_vs_lblc_hashkey(en->addr);
write_lock(&tbl->lock);
list_add(&en->list, &tbl->bucket[hash]);
atomic_inc(&tbl->entries);
write_unlock(&tbl->lock);
return 1;
}
/*
* Get ip_vs_lblc_entry associated with supplied parameters.
*/
static inline struct ip_vs_lblc_entry *
ip_vs_lblc_get(struct ip_vs_lblc_table *tbl, __u32 addr)
{
unsigned hash;
struct ip_vs_lblc_entry *en;
hash = ip_vs_lblc_hashkey(addr);
read_lock(&tbl->lock);
list_for_each_entry(en, &tbl->bucket[hash], list) {
if (en->addr == addr) {
/* HIT */
read_unlock(&tbl->lock);
return en;
}
}
read_unlock(&tbl->lock);
return NULL;
}
/*
* Flush all the entries of the specified table.
*/
static void ip_vs_lblc_flush(struct ip_vs_lblc_table *tbl)
{
int i;
struct ip_vs_lblc_entry *en, *nxt;
for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {
write_lock(&tbl->lock);
list_for_each_entry_safe(en, nxt, &tbl->bucket[i], list) {
ip_vs_lblc_free(en);
atomic_dec(&tbl->entries);
}
write_unlock(&tbl->lock);
}
}
static inline void ip_vs_lblc_full_check(struct ip_vs_lblc_table *tbl)
{
unsigned long now = jiffies;
int i, j;
struct ip_vs_lblc_entry *en, *nxt;
for (i=0, j=tbl->rover; i<IP_VS_LBLC_TAB_SIZE; i++) {
j = (j + 1) & IP_VS_LBLC_TAB_MASK;
write_lock(&tbl->lock);
list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
if (time_before(now,
en->lastuse + sysctl_ip_vs_lblc_expiration))
continue;
ip_vs_lblc_free(en);
atomic_dec(&tbl->entries);
}
write_unlock(&tbl->lock);
}
tbl->rover = j;
}
/*
* Periodical timer handler for IPVS lblc 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_lblc_check_expire(unsigned long data)
{
struct ip_vs_lblc_table *tbl;
unsigned long now = jiffies;
int goal;
int i, j;
struct ip_vs_lblc_entry *en, *nxt;
tbl = (struct ip_vs_lblc_table *)data;
if ((tbl->counter % COUNT_FOR_FULL_EXPIRATION) == 0) {
/* do full expiration check */
ip_vs_lblc_full_check(tbl);
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_LBLC_TAB_SIZE; i++) {
j = (j + 1) & IP_VS_LBLC_TAB_MASK;
write_lock(&tbl->lock);
list_for_each_entry_safe(en, nxt, &tbl->bucket[j], list) {
if (time_before(now, en->lastuse + ENTRY_TIMEOUT))
continue;
ip_vs_lblc_free(en);
atomic_dec(&tbl->entries);
goal--;
}
write_unlock(&tbl->lock);
if (goal <= 0)
break;
}
tbl->rover = j;
out:
mod_timer(&tbl->periodic_timer, jiffies+CHECK_EXPIRE_INTERVAL);
}
static int ip_vs_lblc_init_svc(struct ip_vs_service *svc)
{
int i;
struct ip_vs_lblc_table *tbl;
/*
* Allocate the ip_vs_lblc_table for this service
*/
tbl = kmalloc(sizeof(struct ip_vs_lblc_table), GFP_ATOMIC);
if (tbl == NULL) {
IP_VS_ERR("ip_vs_lblc_init_svc(): no memory\n");
return -ENOMEM;
}
svc->sched_data = tbl;
IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) allocated for "
"current service\n",
sizeof(struct ip_vs_lblc_table));
/*
* Initialize the hash buckets
*/
for (i=0; i<IP_VS_LBLC_TAB_SIZE; i++) {
INIT_LIST_HEAD(&tbl->bucket[i]);
}
rwlock_init(&tbl->lock);
tbl->max_size = IP_VS_LBLC_TAB_SIZE*16;
tbl->rover = 0;
tbl->counter = 1;
/*
* Hook periodic timer for garbage collection
*/
init_timer(&tbl->periodic_timer);
tbl->periodic_timer.data = (unsigned long)tbl;
tbl->periodic_timer.function = ip_vs_lblc_check_expire;
tbl->periodic_timer.expires = jiffies+CHECK_EXPIRE_INTERVAL;
add_timer(&tbl->periodic_timer);
return 0;
}
static int ip_vs_lblc_done_svc(struct ip_vs_service *svc)
{
struct ip_vs_lblc_table *tbl = svc->sched_data;
/* remove periodic timer */
del_timer_sync(&tbl->periodic_timer);
/* got to clean up table entries here */
ip_vs_lblc_flush(tbl);
/* release the table itself */
kfree(svc->sched_data);
IP_VS_DBG(6, "LBLC hash table (memory=%Zdbytes) released\n",
sizeof(struct ip_vs_lblc_table));
return 0;
}
static int ip_vs_lblc_update_svc(struct ip_vs_service *svc)
{
return 0;
}
static inline struct ip_vs_dest *
__ip_vs_wlc_schedule(struct ip_vs_service *svc, struct iphdr *iph)
{
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(6, "LBLC: server %d.%d.%d.%d:%d "
"activeconns %d refcnt %d weight %d overhead %d\n",
NIPQUAD(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_lblc_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
struct ip_vs_dest *dest;
struct ip_vs_lblc_table *tbl;
struct ip_vs_lblc_entry *en;
struct iphdr *iph = skb->nh.iph;
IP_VS_DBG(6, "ip_vs_lblc_schedule(): Scheduling...\n");
tbl = (struct ip_vs_lblc_table *)svc->sched_data;
en = ip_vs_lblc_get(tbl, iph->daddr);
if (en == NULL) {
dest = __ip_vs_wlc_schedule(svc, iph);
if (dest == NULL) {
IP_VS_DBG(1, "no destination available\n");
return NULL;
}
en = ip_vs_lblc_new(iph->daddr, dest);
if (en == NULL) {
return NULL;
}
ip_vs_lblc_hash(tbl, en);
} else {
dest = en->dest;
if (!(dest->flags & IP_VS_DEST_F_AVAILABLE)
|| atomic_read(&dest->weight) <= 0
|| is_overloaded(dest, svc)) {
dest = __ip_vs_wlc_schedule(svc, iph);
if (dest == NULL) {
IP_VS_DBG(1, "no destination available\n");
return NULL;
}
atomic_dec(&en->dest->refcnt);
atomic_inc(&dest->refcnt);
en->dest = dest;
}
}
en->lastuse = jiffies;
IP_VS_DBG(6, "LBLC: destination IP address %u.%u.%u.%u "
"--> server %u.%u.%u.%u:%d\n",
NIPQUAD(en->addr),
NIPQUAD(dest->addr),
ntohs(dest->port));
return dest;
}
/*
* IPVS LBLC Scheduler structure
*/
static struct ip_vs_scheduler ip_vs_lblc_scheduler =
{
.name = "lblc",
.refcnt = ATOMIC_INIT(0),
.module = THIS_MODULE,
.init_service = ip_vs_lblc_init_svc,
.done_service = ip_vs_lblc_done_svc,
.update_service = ip_vs_lblc_update_svc,
.schedule = ip_vs_lblc_schedule,
};
static int __init ip_vs_lblc_init(void)
{
INIT_LIST_HEAD(&ip_vs_lblc_scheduler.n_list);
sysctl_header = register_sysctl_table(lblc_root_table, 0);
return register_ip_vs_scheduler(&ip_vs_lblc_scheduler);
}
static void __exit ip_vs_lblc_cleanup(void)
{
unregister_sysctl_table(sysctl_header);
unregister_ip_vs_scheduler(&ip_vs_lblc_scheduler);
}
module_init(ip_vs_lblc_init);
module_exit(ip_vs_lblc_cleanup);
MODULE_LICENSE("GPL");