Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / net / netfilter / ipvs / ip_vs_nq.c

diff --git a/kernel/net/netfilter/ipvs/ip_vs_nq.c b/kernel/net/netfilter/ipvs/ip_vs_nq.c
new file mode 100644 (file)
index 0000000..a8b6340
--- /dev/null
+++ b/kernel/net/netfilter/ipvs/ip_vs_nq.c
@@ -0,0 +1,143 @@
+/*
+ * IPVS:        Never Queue 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:
+ *
+ */
+
+/*
+ * 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),
+                     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,
+       .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");