mirror of
https://github.com/brain-hackers/linux-brain.git
synced 2024-06-09 23:36:23 +09:00
2874c5fd28
Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
139 lines
3.3 KiB
C
139 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* IPVS: Never Queue scheduling module
|
|
*
|
|
* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
|
|
*
|
|
* Changes:
|
|
*/
|
|
|
|
/*
|
|
* The NQ algorithm adopts a two-speed model. When there is an idle server
|
|
* available, the job will be sent to the idle server, instead of waiting
|
|
* for a fast one. When there is no idle server available, the job will be
|
|
* sent to the server that minimize its expected delay (The Shortest
|
|
* Expected Delay scheduling algorithm).
|
|
*
|
|
* See the following paper for more information:
|
|
* A. Weinrib and S. Shenker, Greed is not enough: Adaptive load sharing
|
|
* in large heterogeneous systems. In Proceedings IEEE INFOCOM'88,
|
|
* pages 986-994, 1988.
|
|
*
|
|
* Thanks must go to Marko Buuri <marko@buuri.name> for talking NQ to me.
|
|
*
|
|
* The difference between NQ and SED is that NQ can improve overall
|
|
* system utilization.
|
|
*
|
|
*/
|
|
|
|
#define KMSG_COMPONENT "IPVS"
|
|
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/kernel.h>
|
|
|
|
#include <net/ip_vs.h>
|
|
|
|
|
|
static inline int
|
|
ip_vs_nq_dest_overhead(struct ip_vs_dest *dest)
|
|
{
|
|
/*
|
|
* We only use the active connection number in the cost
|
|
* calculation here.
|
|
*/
|
|
return atomic_read(&dest->activeconns) + 1;
|
|
}
|
|
|
|
|
|
/*
|
|
* Weighted Least Connection scheduling
|
|
*/
|
|
static struct ip_vs_dest *
|
|
ip_vs_nq_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
|
|
struct ip_vs_iphdr *iph)
|
|
{
|
|
struct ip_vs_dest *dest, *least = NULL;
|
|
int loh = 0, doh;
|
|
|
|
IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
|
|
|
|
/*
|
|
* We calculate the load of each dest server as follows:
|
|
* (server expected 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 connections.
|
|
*/
|
|
|
|
list_for_each_entry_rcu(dest, &svc->destinations, n_list) {
|
|
|
|
if (dest->flags & IP_VS_DEST_F_OVERLOAD ||
|
|
!atomic_read(&dest->weight))
|
|
continue;
|
|
|
|
doh = ip_vs_nq_dest_overhead(dest);
|
|
|
|
/* return the server directly if it is idle */
|
|
if (atomic_read(&dest->activeconns) == 0) {
|
|
least = dest;
|
|
loh = doh;
|
|
goto out;
|
|
}
|
|
|
|
if (!least ||
|
|
((__s64)loh * atomic_read(&dest->weight) >
|
|
(__s64)doh * atomic_read(&least->weight))) {
|
|
least = dest;
|
|
loh = doh;
|
|
}
|
|
}
|
|
|
|
if (!least) {
|
|
ip_vs_scheduler_err(svc, "no destination available");
|
|
return NULL;
|
|
}
|
|
|
|
out:
|
|
IP_VS_DBG_BUF(6, "NQ: server %s:%u "
|
|
"activeconns %d refcnt %d weight %d overhead %d\n",
|
|
IP_VS_DBG_ADDR(least->af, &least->addr),
|
|
ntohs(least->port),
|
|
atomic_read(&least->activeconns),
|
|
refcount_read(&least->refcnt),
|
|
atomic_read(&least->weight), loh);
|
|
|
|
return least;
|
|
}
|
|
|
|
|
|
static struct ip_vs_scheduler ip_vs_nq_scheduler =
|
|
{
|
|
.name = "nq",
|
|
.refcnt = ATOMIC_INIT(0),
|
|
.module = THIS_MODULE,
|
|
.n_list = LIST_HEAD_INIT(ip_vs_nq_scheduler.n_list),
|
|
.schedule = ip_vs_nq_schedule,
|
|
};
|
|
|
|
|
|
static int __init ip_vs_nq_init(void)
|
|
{
|
|
return register_ip_vs_scheduler(&ip_vs_nq_scheduler);
|
|
}
|
|
|
|
static void __exit ip_vs_nq_cleanup(void)
|
|
{
|
|
unregister_ip_vs_scheduler(&ip_vs_nq_scheduler);
|
|
synchronize_rcu();
|
|
}
|
|
|
|
module_init(ip_vs_nq_init);
|
|
module_exit(ip_vs_nq_cleanup);
|
|
MODULE_LICENSE("GPL");
|