From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
---
net/ipv4/ipvs/ip_vs_sed.c | 163 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 163 insertions(+)
create mode 100644 net/ipv4/ipvs/ip_vs_sed.c
(limited to 'net/ipv4/ipvs/ip_vs_sed.c')
diff --git a/net/ipv4/ipvs/ip_vs_sed.c b/net/ipv4/ipvs/ip_vs_sed.c
new file mode 100644
index 000000000000..ff366f7390d9
--- /dev/null
+++ b/net/ipv4/ipvs/ip_vs_sed.c
@@ -0,0 +1,163 @@
+/*
+ * IPVS: Shortest Expected Delay scheduling module
+ *
+ * Version: $Id: ip_vs_sed.c,v 1.1 2003/05/10 03:06:08 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 SED algorithm attempts to minimize each job's expected delay until
+ * completion. The expected delay that the job will experience is
+ * (Ci + 1) / Ui if sent to the ith server, in which Ci is the number of
+ * jobs on the the ith server and Ui is the fixed service rate (weight) of
+ * the ith server. The SED algorithm adopts a greedy policy that each does
+ * what is in its own best interest, i.e. to join the queue which would
+ * minimize its expected delay of completion.
+ *
+ * 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 SED to me.
+ *
+ * The difference between SED and WLC is that SED includes the incoming
+ * job in the cost function (the increment of 1). SED may outperform
+ * WLC, while scheduling big jobs under larger heterogeneous systems
+ * (the server weight varies a lot).
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <net/ip_vs.h>
+
+
+static int
+ip_vs_sed_init_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static int
+ip_vs_sed_done_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static int
+ip_vs_sed_update_svc(struct ip_vs_service *svc)
+{
+ return 0;
+}
+
+
+static inline unsigned int
+ip_vs_sed_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_sed_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
+{
+ struct ip_vs_dest *dest, *least;
+ unsigned int loh, doh;
+
+ IP_VS_DBG(6, "ip_vs_sed_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) > 0) {
+ least = dest;
+ loh = ip_vs_sed_dest_overhead(least);
+ goto nextstage;
+ }
+ }
+ return NULL;
+
+ /*
+ * Find the destination with the least load.
+ */
+ nextstage:
+ list_for_each_entry_continue(dest, &svc->destinations, n_list) {
+ if (dest->flags & IP_VS_DEST_F_OVERLOAD)
+ continue;
+ doh = ip_vs_sed_dest_overhead(dest);
+ if (loh * atomic_read(&dest->weight) >
+ doh * atomic_read(&least->weight)) {
+ least = dest;
+ loh = doh;
+ }
+ }
+
+ IP_VS_DBG(6, "SED: 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_sed_scheduler =
+{
+ .name = "sed",
+ .refcnt = ATOMIC_INIT(0),
+ .module = THIS_MODULE,
+ .init_service = ip_vs_sed_init_svc,
+ .done_service = ip_vs_sed_done_svc,
+ .update_service = ip_vs_sed_update_svc,
+ .schedule = ip_vs_sed_schedule,
+};
+
+
+static int __init ip_vs_sed_init(void)
+{
+ INIT_LIST_HEAD(&ip_vs_sed_scheduler.n_list);
+ return register_ip_vs_scheduler(&ip_vs_sed_scheduler);
+}
+
+static void __exit ip_vs_sed_cleanup(void)
+{
+ unregister_ip_vs_scheduler(&ip_vs_sed_scheduler);
+}
+
+module_init(ip_vs_sed_init);
+module_exit(ip_vs_sed_cleanup);
+MODULE_LICENSE("GPL");
--
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