82dfb6f322
There are schedulers that only schedule based on data available in the service or destination structures and they don't need any persistent storage or initialization routine. These schedulers currently provide dummy functions for the init_service, update_service and/or done_service functions. For the init_service and done_service cases we already have code that only calls these functions, if the scheduler provides them. Do the same for the update_service case and remove the dummy functions from all schedulers. Signed-off-by: Sven Wegener <sven.wegener@stealer.net> Signed-off-by: Simon Horman <horms@verge.net.au>
135 lines
3.3 KiB
C
135 lines
3.3 KiB
C
/*
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* IPVS: Never Queue scheduling module
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Changes:
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*
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*/
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/*
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* The NQ algorithm adopts a two-speed model. When there is an idle server
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* available, the job will be sent to the idle server, instead of waiting
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* for a fast one. When there is no idle server available, the job will be
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* sent to the server that minimize its expected delay (The Shortest
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* Expected Delay scheduling algorithm).
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*
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* See the following paper for more information:
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* A. Weinrib and S. Shenker, Greed is not enough: Adaptive load sharing
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* in large heterogeneous systems. In Proceedings IEEE INFOCOM'88,
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* pages 986-994, 1988.
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*
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* Thanks must go to Marko Buuri <marko@buuri.name> for talking NQ to me.
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*
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* The difference between NQ and SED is that NQ can improve overall
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* system utilization.
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <net/ip_vs.h>
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static inline unsigned int
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ip_vs_nq_dest_overhead(struct ip_vs_dest *dest)
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{
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/*
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* We only use the active connection number in the cost
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* calculation here.
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*/
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return atomic_read(&dest->activeconns) + 1;
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}
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/*
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* Weighted Least Connection scheduling
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*/
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static struct ip_vs_dest *
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ip_vs_nq_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
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{
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struct ip_vs_dest *dest, *least = NULL;
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unsigned int loh = 0, doh;
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IP_VS_DBG(6, "ip_vs_nq_schedule(): Scheduling...\n");
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/*
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* We calculate the load of each dest server as follows:
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* (server expected overhead) / dest->weight
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*
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* Remember -- no floats in kernel mode!!!
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* The comparison of h1*w2 > h2*w1 is equivalent to that of
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* h1/w1 > h2/w2
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* if every weight is larger than zero.
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*
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* The server with weight=0 is quiesced and will not receive any
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* new connections.
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*/
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list_for_each_entry(dest, &svc->destinations, n_list) {
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if (dest->flags & IP_VS_DEST_F_OVERLOAD ||
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!atomic_read(&dest->weight))
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continue;
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doh = ip_vs_nq_dest_overhead(dest);
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/* return the server directly if it is idle */
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if (atomic_read(&dest->activeconns) == 0) {
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least = dest;
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loh = doh;
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goto out;
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}
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if (!least ||
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(loh * atomic_read(&dest->weight) >
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doh * atomic_read(&least->weight))) {
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least = dest;
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loh = doh;
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}
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}
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if (!least)
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return NULL;
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out:
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IP_VS_DBG(6, "NQ: server %u.%u.%u.%u:%u "
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"activeconns %d refcnt %d weight %d overhead %d\n",
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NIPQUAD(least->addr), ntohs(least->port),
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atomic_read(&least->activeconns),
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atomic_read(&least->refcnt),
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atomic_read(&least->weight), loh);
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return least;
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}
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static struct ip_vs_scheduler ip_vs_nq_scheduler =
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{
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.name = "nq",
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.refcnt = ATOMIC_INIT(0),
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.module = THIS_MODULE,
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.n_list = LIST_HEAD_INIT(ip_vs_nq_scheduler.n_list),
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.schedule = ip_vs_nq_schedule,
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};
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static int __init ip_vs_nq_init(void)
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{
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return register_ip_vs_scheduler(&ip_vs_nq_scheduler);
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}
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static void __exit ip_vs_nq_cleanup(void)
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{
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unregister_ip_vs_scheduler(&ip_vs_nq_scheduler);
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}
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module_init(ip_vs_nq_init);
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module_exit(ip_vs_nq_cleanup);
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MODULE_LICENSE("GPL");
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