[PATCH] top level scheduler domain for ia64

[Jesse Barnes <jbarnes@engr.sgi.com>]

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Some have noticed that the overlapping sched domains code doesn't quite work 
as intended (it results in disjoint domains on some machines), and that a top 
level, machine spanning domain is needed.  This patch from John Hawkes adds 
it to the ia64 code.  This allows processes to run on all CPUs in large 
systems, though balancing is limited.  It should go to Linus soon now 
otherwise large systems will only have ~16p (depending on topology) usable by 
the scheduler.  I sanity checked it on a small system after rediffing John's 
original, and he's done some testing on very large systems.

Nick, can you buy off on the sched.c change?  Alternatively, do you want to 
send that fix separately John?

Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>

Thanks,
Jesse

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===== arch/ia64/kernel/domain.c 1.3 vs edited =====
--- 1.3/arch/ia64/kernel/domain.c	2004-10-18 22:26:51 -07:00
+++ edited/arch/ia64/kernel/domain.c	2004-10-19 14:18:07 -07:00
@@ -119,6 +119,14 @@
  */
 static DEFINE_PER_CPU(struct sched_domain, node_domains);
 static struct sched_group *sched_group_nodes[MAX_NUMNODES];
+
+static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
+static struct sched_group sched_group_allnodes[MAX_NUMNODES];
+
+static int __devinit cpu_to_allnodes_group(int cpu)
+{
+	return cpu_to_node(cpu);
+}
 #endif
 
 /*
@@ -149,9 +157,21 @@
 		cpus_and(nodemask, nodemask, cpu_default_map);
 
 #ifdef CONFIG_NUMA
+		if (num_online_cpus()
+				> SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
+			sd = &per_cpu(allnodes_domains, i);
+			*sd = SD_ALLNODES_INIT;
+			sd->span = cpu_default_map;
+			group = cpu_to_allnodes_group(i);
+			sd->groups = &sched_group_allnodes[group];
+			p = sd;
+		} else
+			p = NULL;
+
 		sd = &per_cpu(node_domains, i);
 		*sd = SD_NODE_INIT;
 		sd->span = sched_domain_node_span(node);
+		sd->parent = p;
 		cpus_and(sd->span, sd->span, cpu_default_map);
 #endif
 
@@ -201,6 +221,9 @@
 	}
 
 #ifdef CONFIG_NUMA
+	init_sched_build_groups(sched_group_allnodes, cpu_default_map,
+				&cpu_to_allnodes_group);
+
 	for (i = 0; i < MAX_NUMNODES; i++) {
 		/* Set up node groups */
 		struct sched_group *sg, *prev;
@@ -282,6 +305,15 @@
 		power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
 				(cpus_weight(sd->groups->cpumask)-1) / 10;
 		sd->groups->cpu_power = power;
+
+#ifdef CONFIG_NUMA
+		sd = &per_cpu(allnodes_domains, i);
+		if (sd->groups) {
+			power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
+				(cpus_weight(sd->groups->cpumask)-1) / 10;
+			sd->groups->cpu_power = power;
+		}
+#endif
 	}
 
 #ifdef CONFIG_NUMA
===== include/asm-ia64/topology.h 1.12 vs edited =====
--- 1.12/include/asm-ia64/topology.h	2004-10-18 22:26:52 -07:00
+++ edited/include/asm-ia64/topology.h	2004-10-19 14:18:06 -07:00
@@ -58,7 +58,26 @@
 				| SD_BALANCE_EXEC	\
 				| SD_WAKE_BALANCE,	\
 	.last_balance		= jiffies,		\
-	.balance_interval	= 10,			\
+	.balance_interval	= 1,			\
+	.nr_balance_failed	= 0,			\
+}
+
+/* sched_domains SD_ALLNODES_INIT for IA64 NUMA machines */
+#define SD_ALLNODES_INIT (struct sched_domain) {	\
+	.span			= CPU_MASK_NONE,	\
+	.parent			= NULL,			\
+	.groups			= NULL,			\
+	.min_interval		= 80,			\
+	.max_interval		= 320,			\
+	.busy_factor		= 320,			\
+	.imbalance_pct		= 125,			\
+	.cache_hot_time		= (10*1000000),		\
+	.cache_nice_tries	= 1,			\
+	.per_cpu_gain		= 100,			\
+	.flags			= SD_LOAD_BALANCE	\
+				| SD_BALANCE_EXEC,	\
+	.last_balance		= jiffies,		\
+	.balance_interval	= 100*(63+num_online_cpus())/64,   \
 	.nr_balance_failed	= 0,			\
 }
 
===== kernel/sched.c 1.367 vs edited =====
--- 1.367/kernel/sched.c	2004-10-18 22:26:52 -07:00
+++ edited/kernel/sched.c	2004-10-19 14:18:06 -07:00
@@ -4378,11 +4378,10 @@
 			printk("domain %d: ", level);
 
 			if (!(sd->flags & SD_LOAD_BALANCE)) {
-				printk("does not balance");
+				printk("does not load-balance");
 				if (sd->parent)
 					printk(" ERROR !SD_LOAD_BALANCE domain has parent");
 				printk("\n");
-				break;
 			}
 
 			printk("span %s\n", str);