271 lines
7.0 KiB
C
271 lines
7.0 KiB
C
/*
|
|
* IPVS: Weighted Round-Robin Scheduling module
|
|
*
|
|
* Authors: Wensong Zhang <wensong@linuxvirtualserver.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:
|
|
* Wensong Zhang : changed the ip_vs_wrr_schedule to return dest
|
|
* Wensong Zhang : changed some comestics things for debugging
|
|
* Wensong Zhang : changed for the d-linked destination list
|
|
* Wensong Zhang : added the ip_vs_wrr_update_svc
|
|
* Julian Anastasov : fixed the bug of returning destination
|
|
* with weight 0 when all weights are zero
|
|
*
|
|
*/
|
|
|
|
#define KMSG_COMPONENT "IPVS"
|
|
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/net.h>
|
|
#include <linux/gcd.h>
|
|
|
|
#include <net/ip_vs.h>
|
|
|
|
/* The WRR algorithm depends on some caclulations:
|
|
* - mw: maximum weight
|
|
* - di: weight step, greatest common divisor from all weights
|
|
* - cw: current required weight
|
|
* As result, all weights are in the [di..mw] range with a step=di.
|
|
*
|
|
* First, we start with cw = mw and select dests with weight >= cw.
|
|
* Then cw is reduced with di and all dests are checked again.
|
|
* Last pass should be with cw = di. We have mw/di passes in total:
|
|
*
|
|
* pass 1: cw = max weight
|
|
* pass 2: cw = max weight - di
|
|
* pass 3: cw = max weight - 2 * di
|
|
* ...
|
|
* last pass: cw = di
|
|
*
|
|
* Weights are supposed to be >= di but we run in parallel with
|
|
* weight changes, it is possible some dest weight to be reduced
|
|
* below di, bad if it is the only available dest.
|
|
*
|
|
* So, we modify how mw is calculated, now it is reduced with (di - 1),
|
|
* so that last cw is 1 to catch such dests with weight below di:
|
|
* pass 1: cw = max weight - (di - 1)
|
|
* pass 2: cw = max weight - di - (di - 1)
|
|
* pass 3: cw = max weight - 2 * di - (di - 1)
|
|
* ...
|
|
* last pass: cw = 1
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* current destination pointer for weighted round-robin scheduling
|
|
*/
|
|
struct ip_vs_wrr_mark {
|
|
struct ip_vs_dest *cl; /* current dest or head */
|
|
int cw; /* current weight */
|
|
int mw; /* maximum weight */
|
|
int di; /* decreasing interval */
|
|
struct rcu_head rcu_head;
|
|
};
|
|
|
|
|
|
static int ip_vs_wrr_gcd_weight(struct ip_vs_service *svc)
|
|
{
|
|
struct ip_vs_dest *dest;
|
|
int weight;
|
|
int g = 0;
|
|
|
|
list_for_each_entry(dest, &svc->destinations, n_list) {
|
|
weight = atomic_read(&dest->weight);
|
|
if (weight > 0) {
|
|
if (g > 0)
|
|
g = gcd(weight, g);
|
|
else
|
|
g = weight;
|
|
}
|
|
}
|
|
return g ? g : 1;
|
|
}
|
|
|
|
|
|
/*
|
|
* Get the maximum weight of the service destinations.
|
|
*/
|
|
static int ip_vs_wrr_max_weight(struct ip_vs_service *svc)
|
|
{
|
|
struct ip_vs_dest *dest;
|
|
int new_weight, weight = 0;
|
|
|
|
list_for_each_entry(dest, &svc->destinations, n_list) {
|
|
new_weight = atomic_read(&dest->weight);
|
|
if (new_weight > weight)
|
|
weight = new_weight;
|
|
}
|
|
|
|
return weight;
|
|
}
|
|
|
|
|
|
static int ip_vs_wrr_init_svc(struct ip_vs_service *svc)
|
|
{
|
|
struct ip_vs_wrr_mark *mark;
|
|
|
|
/*
|
|
* Allocate the mark variable for WRR scheduling
|
|
*/
|
|
mark = kmalloc(sizeof(struct ip_vs_wrr_mark), GFP_KERNEL);
|
|
if (mark == NULL)
|
|
return -ENOMEM;
|
|
|
|
mark->cl = list_entry(&svc->destinations, struct ip_vs_dest, n_list);
|
|
mark->di = ip_vs_wrr_gcd_weight(svc);
|
|
mark->mw = ip_vs_wrr_max_weight(svc) - (mark->di - 1);
|
|
mark->cw = mark->mw;
|
|
svc->sched_data = mark;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static void ip_vs_wrr_done_svc(struct ip_vs_service *svc)
|
|
{
|
|
struct ip_vs_wrr_mark *mark = svc->sched_data;
|
|
|
|
/*
|
|
* Release the mark variable
|
|
*/
|
|
kfree_rcu(mark, rcu_head);
|
|
}
|
|
|
|
|
|
static int ip_vs_wrr_dest_changed(struct ip_vs_service *svc,
|
|
struct ip_vs_dest *dest)
|
|
{
|
|
struct ip_vs_wrr_mark *mark = svc->sched_data;
|
|
|
|
spin_lock_bh(&svc->sched_lock);
|
|
mark->cl = list_entry(&svc->destinations, struct ip_vs_dest, n_list);
|
|
mark->di = ip_vs_wrr_gcd_weight(svc);
|
|
mark->mw = ip_vs_wrr_max_weight(svc) - (mark->di - 1);
|
|
if (mark->cw > mark->mw || !mark->cw)
|
|
mark->cw = mark->mw;
|
|
else if (mark->di > 1)
|
|
mark->cw = (mark->cw / mark->di) * mark->di + 1;
|
|
spin_unlock_bh(&svc->sched_lock);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* Weighted Round-Robin Scheduling
|
|
*/
|
|
static struct ip_vs_dest *
|
|
ip_vs_wrr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
|
|
struct ip_vs_iphdr *iph)
|
|
{
|
|
struct ip_vs_dest *dest, *last, *stop = NULL;
|
|
struct ip_vs_wrr_mark *mark = svc->sched_data;
|
|
bool last_pass = false, restarted = false;
|
|
|
|
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
|
|
|
|
spin_lock_bh(&svc->sched_lock);
|
|
dest = mark->cl;
|
|
/* No available dests? */
|
|
if (mark->mw == 0)
|
|
goto err_noavail;
|
|
last = dest;
|
|
/* Stop only after all dests were checked for weight >= 1 (last pass) */
|
|
while (1) {
|
|
list_for_each_entry_continue_rcu(dest,
|
|
&svc->destinations,
|
|
n_list) {
|
|
if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&
|
|
atomic_read(&dest->weight) >= mark->cw)
|
|
goto found;
|
|
if (dest == stop)
|
|
goto err_over;
|
|
}
|
|
mark->cw -= mark->di;
|
|
if (mark->cw <= 0) {
|
|
mark->cw = mark->mw;
|
|
/* Stop if we tried last pass from first dest:
|
|
* 1. last_pass: we started checks when cw > di but
|
|
* then all dests were checked for w >= 1
|
|
* 2. last was head: the first and only traversal
|
|
* was for weight >= 1, for all dests.
|
|
*/
|
|
if (last_pass ||
|
|
&last->n_list == &svc->destinations)
|
|
goto err_over;
|
|
restarted = true;
|
|
}
|
|
last_pass = mark->cw <= mark->di;
|
|
if (last_pass && restarted &&
|
|
&last->n_list != &svc->destinations) {
|
|
/* First traversal was for w >= 1 but only
|
|
* for dests after 'last', now do the same
|
|
* for all dests up to 'last'.
|
|
*/
|
|
stop = last;
|
|
}
|
|
}
|
|
|
|
found:
|
|
IP_VS_DBG_BUF(6, "WRR: server %s:%u "
|
|
"activeconns %d refcnt %d weight %d\n",
|
|
IP_VS_DBG_ADDR(svc->af, &dest->addr), ntohs(dest->port),
|
|
atomic_read(&dest->activeconns),
|
|
atomic_read(&dest->refcnt),
|
|
atomic_read(&dest->weight));
|
|
mark->cl = dest;
|
|
|
|
out:
|
|
spin_unlock_bh(&svc->sched_lock);
|
|
return dest;
|
|
|
|
err_noavail:
|
|
mark->cl = dest;
|
|
dest = NULL;
|
|
ip_vs_scheduler_err(svc, "no destination available");
|
|
goto out;
|
|
|
|
err_over:
|
|
mark->cl = dest;
|
|
dest = NULL;
|
|
ip_vs_scheduler_err(svc, "no destination available: "
|
|
"all destinations are overloaded");
|
|
goto out;
|
|
}
|
|
|
|
|
|
static struct ip_vs_scheduler ip_vs_wrr_scheduler = {
|
|
.name = "wrr",
|
|
.refcnt = ATOMIC_INIT(0),
|
|
.module = THIS_MODULE,
|
|
.n_list = LIST_HEAD_INIT(ip_vs_wrr_scheduler.n_list),
|
|
.init_service = ip_vs_wrr_init_svc,
|
|
.done_service = ip_vs_wrr_done_svc,
|
|
.add_dest = ip_vs_wrr_dest_changed,
|
|
.del_dest = ip_vs_wrr_dest_changed,
|
|
.upd_dest = ip_vs_wrr_dest_changed,
|
|
.schedule = ip_vs_wrr_schedule,
|
|
};
|
|
|
|
static int __init ip_vs_wrr_init(void)
|
|
{
|
|
return register_ip_vs_scheduler(&ip_vs_wrr_scheduler) ;
|
|
}
|
|
|
|
static void __exit ip_vs_wrr_cleanup(void)
|
|
{
|
|
unregister_ip_vs_scheduler(&ip_vs_wrr_scheduler);
|
|
synchronize_rcu();
|
|
}
|
|
|
|
module_init(ip_vs_wrr_init);
|
|
module_exit(ip_vs_wrr_cleanup);
|
|
MODULE_LICENSE("GPL");
|