[PATCH] sched: IA64 add disjoint NUMA domain support

Implement disjoint NUMA domain setup for IA64 architecture.  Most of the code
was what was ripped out of kernel/sched.c, which was written by Jesse Barnes
<jbarnes@sgi.com>.  I fixed up the tricky NUMA groups initialistion.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ia64/kernel/Makefile

@@ -14,7 +14,7 @@ obj-$(CONFIG_IA64_HP_ZX1)	+= acpi-ext.o
 obj-$(CONFIG_IA64_PALINFO)	+= palinfo.o
 obj-$(CONFIG_IOSAPIC)		+= iosapic.o
 obj-$(CONFIG_MODULES)		+= module.o
-obj-$(CONFIG_SMP)		+= smp.o smpboot.o
+obj-$(CONFIG_SMP)		+= smp.o smpboot.o domain.o
 obj-$(CONFIG_PERFMON)		+= perfmon_default_smpl.o
 obj-$(CONFIG_IA64_CYCLONE)	+= cyclone.o
 obj-$(CONFIG_IA64_MCA_RECOVERY)	+= mca_recovery.o

arch/ia64/kernel/domain.c

+/*
+ * arch/ia64/kernel/domain.c
+ * Architecture specific sched-domains builder.
+ *
+ * Copyright (C) 2004  Linus Torvalds
+ */
+
+#include <linux/sched.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/cpumask.h>
+#include <linux/init.h>
+#include <linux/topology.h>
+#include <asm/processor.h>
+
+#define SD_NODES_PER_DOMAIN 4
+
+#ifdef CONFIG_NUMA
+/**
+ * find_next_best_node - find the next node to include in a sched_domain
+ * @node: node whose sched_domain we're building
+ * @used_nodes: nodes already in the sched_domain
+ *
+ * Find the next node to include in a given scheduling domain.  Simply
+ * finds the closest node not already in the @used_nodes map.
+ *
+ * Should use nodemask_t.
+ */
+static int __devinit find_next_best_node(int node, unsigned long *used_nodes)
+{
+	int i, n, val, min_val, best_node = 0;
+
+	min_val = INT_MAX;
+
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		/* Start at @node */
+		n = (node + i) % MAX_NUMNODES;
+
+		/* Skip already used nodes */
+		if (test_bit(n, used_nodes))
+			continue;
+
+		/* Simple min distance search */
+		val = node_distance(node, i);
+
+		if (val < min_val) {
+			min_val = val;
+			best_node = n;
+		}
+	}
+
+	set_bit(best_node, used_nodes);
+	return best_node;
+}
+
+/**
+ * sched_domain_node_span - get a cpumask for a node's sched_domain
+ * @node: node whose cpumask we're constructing
+ * @size: number of nodes to include in this span
+ *
+ * Given a node, construct a good cpumask for its sched_domain to span.  It
+ * should be one that prevents unnecessary balancing, but also spreads tasks
+ * out optimally.
+ */
+static cpumask_t __devinit sched_domain_node_span(int node)
+{
+	int i;
+	cpumask_t span;
+	DECLARE_BITMAP(used_nodes, MAX_NUMNODES);
+
+	cpus_clear(span);
+	bitmap_zero(used_nodes, MAX_NUMNODES);
+
+	for (i = 0; i < SD_NODES_PER_DOMAIN; i++) {
+		int next_node = find_next_best_node(node, used_nodes);
+		cpumask_t  nodemask;
+
+		nodemask = node_to_cpumask(next_node);
+		cpus_or(span, span, nodemask);
+	}
+
+	return span;
+}
+#endif
+
+/*
+ * At the moment, CONFIG_SCHED_SMT is never defined, but leave it in so we
+ * can switch it on easily if needed.
+ */
+#ifdef CONFIG_SCHED_SMT
+static DEFINE_PER_CPU(struct sched_domain, cpu_domains);
+static struct sched_group sched_group_cpus[NR_CPUS];
+static int __devinit cpu_to_cpu_group(int cpu)
+{
+	return cpu;
+}
+#endif
+
+static DEFINE_PER_CPU(struct sched_domain, phys_domains);
+static struct sched_group sched_group_phys[NR_CPUS];
+static int __devinit cpu_to_phys_group(int cpu)
+{
+#ifdef CONFIG_SCHED_SMT
+	return first_cpu(cpu_sibling_map[cpu]);
+#else
+	return cpu;
+#endif
+}
+
+#ifdef CONFIG_NUMA
+/*
+ * The init_sched_build_groups can't handle what we want to do with node
+ * groups, so roll our own. Now each node has its own list of groups which
+ * gets dynamically allocated.
+ */
+static DEFINE_PER_CPU(struct sched_domain, node_domains);
+static struct sched_group *sched_group_nodes[MAX_NUMNODES];
+#endif
+
+/*
+ * Set up scheduler domains and groups.  Callers must hold the hotplug lock.
+ */
+void __devinit arch_init_sched_domains(void)
+{
+	int i;
+	cpumask_t cpu_default_map;
+
+	/*
+	 * Setup mask for cpus without special case scheduling requirements.
+	 * For now this just excludes isolated cpus, but could be used to
+	 * exclude other special cases in the future.
+	 */
+	cpus_complement(cpu_default_map, cpu_isolated_map);
+	cpus_and(cpu_default_map, cpu_default_map, cpu_online_map);
+
+	/*
+	 * Set up domains. Isolated domains just stay on the dummy domain.
+	 */
+	for_each_cpu_mask(i, cpu_default_map) {
+		int group;
+		struct sched_domain *sd = NULL, *p;
+		cpumask_t nodemask = node_to_cpumask(cpu_to_node(i));
+
+		cpus_and(nodemask, nodemask, cpu_default_map);
+
+#ifdef CONFIG_NUMA
+		sd = &per_cpu(node_domains, i);
+		*sd = SD_NODE_INIT;
+		sd->span = sched_domain_node_span(cpu_to_node(i));
+		cpus_and(sd->span, sd->span, cpu_default_map);
+#endif
+
+		p = sd;
+		sd = &per_cpu(phys_domains, i);
+		group = cpu_to_phys_group(i);
+		*sd = SD_CPU_INIT;
+		sd->span = nodemask;
+		sd->parent = p;
+		sd->groups = &sched_group_phys[group];
+
+#ifdef CONFIG_SCHED_SMT
+		p = sd;
+		sd = &per_cpu(cpu_domains, i);
+		group = cpu_to_cpu_group(i);
+		*sd = SD_SIBLING_INIT;
+		sd->span = cpu_sibling_map[i];
+		cpus_and(sd->span, sd->span, cpu_default_map);
+		sd->parent = p;
+		sd->groups = &sched_group_cpus[group];
+#endif
+	}
+
+#ifdef CONFIG_SCHED_SMT
+	/* Set up CPU (sibling) groups */
+	for_each_cpu_mask(i, cpu_default_map) {
+		cpumask_t this_sibling_map = cpu_sibling_map[i];
+		cpus_and(this_sibling_map, this_sibling_map, cpu_default_map);
+		if (i != first_cpu(this_sibling_map))
+			continue;
+
+		init_sched_build_groups(sched_group_cpus, this_sibling_map,
+						&cpu_to_cpu_group);
+	}
+#endif
+
+	/* Set up physical groups */
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		cpumask_t nodemask = node_to_cpumask(i);
+
+		cpus_and(nodemask, nodemask, cpu_default_map);
+		if (cpus_empty(nodemask))
+			continue;
+
+		init_sched_build_groups(sched_group_phys, nodemask,
+						&cpu_to_phys_group);
+	}
+
+#ifdef CONFIG_NUMA
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		/* Set up node groups */
+		struct sched_group *sg, *prev;
+		cpumask_t nodemask = node_to_cpumask(i);
+		cpumask_t domainspan;
+		cpumask_t covered = CPU_MASK_NONE;
+		int j;
+
+		cpus_and(nodemask, nodemask, cpu_default_map);
+		if (cpus_empty(nodemask))
+			continue;
+
+		domainspan = sched_domain_node_span(i);
+		cpus_and(domainspan, domainspan, cpu_default_map);
+
+		sg = kmalloc(sizeof(struct sched_group), GFP_KERNEL);
+		sched_group_nodes[i] = sg;
+		for_each_cpu_mask(j, nodemask) {
+			struct sched_domain *sd;
+			sd = &per_cpu(node_domains, j);
+			sd->groups = sg;
+			if (sd->groups == NULL) {
+				/* Turn off balancing if we have no groups */
+				sd->flags = 0;
+			}
+		}
+		if (!sg) {
+			printk(KERN_WARNING
+			"Can not alloc domain group for node %d\n", i);
+			continue;
+		}
+		sg->cpu_power = 0;
+		sg->cpumask = nodemask;
+		cpus_or(covered, covered, nodemask);
+		prev = sg;
+
+		for (j = 0; j < MAX_NUMNODES; j++) {
+			cpumask_t tmp, notcovered;
+			int n = (i + j) % MAX_NUMNODES;
+
+			cpus_complement(notcovered, covered);
+			cpus_and(tmp, notcovered, cpu_default_map);
+			cpus_and(tmp, tmp, domainspan);
+			if (cpus_empty(tmp))
+				break;
+
+			nodemask = node_to_cpumask(n);
+			cpus_and(tmp, tmp, nodemask);
+			if (cpus_empty(tmp))
+				continue;
+
+			sg = kmalloc(sizeof(struct sched_group), GFP_KERNEL);
+			if (!sg) {
+				printk(KERN_WARNING
+				"Can not alloc domain group for node %d\n", j);
+				break;
+			}
+			sg->cpu_power = 0;
+			sg->cpumask = tmp;
+			cpus_or(covered, covered, tmp);
+			prev->next = sg;
+			prev = sg;
+		}
+		prev->next = sched_group_nodes[i];
+	}
+#endif
+
+	/* Calculate CPU power for physical packages and nodes */
+	for_each_cpu_mask(i, cpu_default_map) {
+		int power;
+		struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+		sd = &per_cpu(cpu_domains, i);
+		power = SCHED_LOAD_SCALE;
+		sd->groups->cpu_power = power;
+#endif
+
+		sd = &per_cpu(phys_domains, i);
+		power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
+				(cpus_weight(sd->groups->cpumask)-1) / 10;
+		sd->groups->cpu_power = power;
+	}
+
+#ifdef CONFIG_NUMA
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		struct sched_group *sg = sched_group_nodes[i];
+		int j;
+
+		if (sg == NULL)
+			continue;
+next_sg:
+		for_each_cpu_mask(j, sg->cpumask) {
+			struct sched_domain *sd;
+			int power;
+
+			sd = &per_cpu(phys_domains, j);
+			if (j != first_cpu(sd->groups->cpumask)) {
+				/*
+				 * Only add "power" once for each
+				 * physical package.
+				 */
+				continue;
+			}
+			power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
+				(cpus_weight(sd->groups->cpumask)-1) / 10;
+
+			sg->cpu_power += power;
+		}
+		sg = sg->next;
+		if (sg != sched_group_nodes[i])
+			goto next_sg;
+	}
+#endif
+
+	/* Attach the domains */
+	for_each_online_cpu(i) {
+		struct sched_domain *sd;
+#ifdef CONFIG_SCHED_SMT
+		sd = &per_cpu(cpu_domains, i);
+#else
+		sd = &per_cpu(phys_domains, i);
+#endif
+		cpu_attach_domain(sd, i);
+	}
+}
+
+void __devinit arch_destroy_sched_domains(void)
+{
+#ifdef CONFIG_NUMA
+	int i;
+	for (i = 0; i < MAX_NUMNODES; i++) {
+		struct sched_group *oldsg, *sg = sched_group_nodes[i];
+		if (sg == NULL)
+			continue;
+		sg = sg->next;
+next_sg:
+		oldsg = sg;
+		sg = sg->next;
+		kfree(oldsg);
+		if (oldsg != sched_group_nodes[i])
+			goto next_sg;
+		sched_group_nodes[i] = NULL;
+	}
+#endif
+}
+

include/asm-ia64/processor.h

@@ -20,6 +20,9 @@
 #include <asm/ptrace.h>
 #include <asm/ustack.h>
 
+/* Our arch specific arch_init_sched_domain is in arch/ia64/kernel/domain.c */
+#define ARCH_HAS_SCHED_DOMAIN
+
 #define IA64_NUM_DBG_REGS	8
 /*
  * Limits for PMC and PMD are set to less than maximum architected values