summaryrefslogtreecommitdiffstats
path: root/net/ipv4/ipvs/ip_vs_nq.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/ipv4/ipvs/ip_vs_nq.c')
-rw-r--r--net/ipv4/ipvs/ip_vs_nq.c161
1 files changed, 161 insertions, 0 deletions
diff --git a/net/ipv4/ipvs/ip_vs_nq.c b/net/ipv4/ipvs/ip_vs_nq.c
new file mode 100644
index 0000000..bc2a9e5
--- /dev/null
+++ b/net/ipv4/ipvs/ip_vs_nq.c
@@ -0,0 +1,161 @@
+/*
+ * IPVS: Never Queue scheduling module
+ *
+ * Version: $Id: ip_vs_nq.c,v 1.2 2003/06/08 09:31:19 wensong Exp $
+ *
+ * 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:
+ *
+ */
+
+/*
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <net/ip_vs.h>
+
+
+static int
+ip_vs_nq_init_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static int
+ip_vs_nq_done_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static int
+ip_vs_nq_update_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static inline unsigned 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_dest *dest, *least = NULL;
+ unsigned int loh = 0, doh;
+
+ IP_VS_DBG(6, "ip_vs_nq_schedule(): Scheduling...\n");
+
+ /*
+ * 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(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 ||
+ (loh * atomic_read(&dest->weight) >
+ doh * atomic_read(&least->weight))) {
+ least = dest;
+ loh = doh;
+ }
+ }
+
+ if (!least)
+ return NULL;
+
+ out:
+ IP_VS_DBG(6, "NQ: server %u.%u.%u.%u:%u "
+ "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;
+}
+
+
+static struct ip_vs_scheduler ip_vs_nq_scheduler =
+{
+ .name = "nq",
+ .refcnt = ATOMIC_INIT(0),
+ .module = THIS_MODULE,
+ .init_service = ip_vs_nq_init_svc,
+ .done_service = ip_vs_nq_done_svc,
+ .update_service = ip_vs_nq_update_svc,
+ .schedule = ip_vs_nq_schedule,
+};
+
+
+static int __init ip_vs_nq_init(void)
+{
+ INIT_LIST_HEAD(&ip_vs_nq_scheduler.n_list);
+ 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);
+}
+
+module_init(ip_vs_nq_init);
+module_exit(ip_vs_nq_cleanup);
+MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud