[PATCH] sched_domains: Make SD_NODE_INIT per-arch #2

Here's yet another version of a patch to implement per-arch SD_*_INITs. 
This follows the same basic idea of my last patch, but

1) defines an arch-specific SD_NODE_INIT for the 4 NUMA arches (i386,
   x86_64, IA64 & PPC64),

2) defines *default* SD_CPU_INIT & SD_SIBLING_INIT for *all* arches,
   with the possibility of them being overridden by simply defining an
   arch-specific version in include/asm/topology.h.

The motivation behind the third version of this patch is that Martin feels
that there should be no "default" NUMA initializer because NUMA
characteristics are *very* arch/platform specific, and hence a "default"
NUMA initializer can only lead to confusion.  I agree with most of that,
but don't quite see as much harm in having a default as he does.
Nevertheless, to keep him quiet, I've run up this version of the patch. 
Martin, please run this through your magic test suite and make sure I
didn't break anything trivial.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 74 insertions, 72 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0e089c693b81..69648ed7fd2b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -29,6 +29,7 @@
 #include <linux/completion.h>
 #include <linux/pid.h>
 #include <linux/percpu.h>
+#include <linux/topology.h>
 
 struct exec_domain;
 
@@ -482,78 +483,7 @@ extern cpumask_t cpu_isolated_map;
 extern void init_sched_build_groups(struct sched_group groups[],
 	                        cpumask_t span, int (*group_fn)(int cpu));
 extern void cpu_attach_domain(struct sched_domain *sd, int cpu);
-#endif
-
-#ifndef ARCH_HAS_SCHED_TUNE
-#ifdef CONFIG_SCHED_SMT
-#define ARCH_HAS_SCHED_WAKE_IDLE
-/* Common values for SMT siblings */
-#define SD_SIBLING_INIT (struct sched_domain) {		\
-	.span			= CPU_MASK_NONE,	\
-	.parent			= NULL,			\
-	.groups			= NULL,			\
-	.min_interval		= 1,			\
-	.max_interval		= 2,			\
-	.busy_factor		= 8,			\
-	.imbalance_pct		= 110,			\
-	.cache_hot_time		= 0,			\
-	.cache_nice_tries	= 0,			\
-	.per_cpu_gain		= 25,			\
-	.flags			= SD_LOAD_BALANCE	\
-				| SD_BALANCE_NEWIDLE	\
-				| SD_BALANCE_EXEC	\
-				| SD_WAKE_AFFINE	\
-				| SD_WAKE_IDLE		\
-				| SD_SHARE_CPUPOWER,	\
-	.last_balance		= jiffies,		\
-	.balance_interval	= 1,			\
-	.nr_balance_failed	= 0,			\
-}
-#endif
-
-/* Common values for CPUs */
-#define SD_CPU_INIT (struct sched_domain) {		\
-	.span			= CPU_MASK_NONE,	\
-	.parent			= NULL,			\
-	.groups			= NULL,			\
-	.min_interval		= 1,			\
-	.max_interval		= 4,			\
-	.busy_factor		= 64,			\
-	.imbalance_pct		= 125,			\
-	.cache_hot_time		= (5*1000/2),		\
-	.cache_nice_tries	= 1,			\
-	.per_cpu_gain		= 100,			\
-	.flags			= SD_LOAD_BALANCE	\
-				| SD_BALANCE_NEWIDLE	\
-				| SD_BALANCE_EXEC	\
-				| SD_WAKE_AFFINE	\
-				| SD_WAKE_BALANCE,	\
-	.last_balance		= jiffies,		\
-	.balance_interval	= 1,			\
-	.nr_balance_failed	= 0,			\
-}
-
-#if defined(CONFIG_NUMA) && !defined(SD_NODE_INIT)
-#define SD_NODE_INIT (struct sched_domain) {		\
-	.span			= CPU_MASK_NONE,	\
-	.parent			= NULL,			\
-	.groups			= NULL,			\
-	.min_interval		= 8,			\
-	.max_interval		= 32,			\
-	.busy_factor		= 32,			\
-	.imbalance_pct		= 125,			\
-	.cache_hot_time		= (10*1000),		\
-	.cache_nice_tries	= 1,			\
-	.per_cpu_gain		= 100,			\
-	.flags			= SD_LOAD_BALANCE	\
-				| SD_BALANCE_EXEC	\
-				| SD_WAKE_BALANCE,	\
-	.last_balance		= jiffies,		\
-	.balance_interval	= 1,			\
-	.nr_balance_failed	= 0,			\
-}
-#endif
-#endif /* ARCH_HAS_SCHED_TUNE */
+#endif /* ARCH_HAS_SCHED_DOMAIN */
 #endif /* CONFIG_SMP */
 
 
diff --git a/include/linux/topology.h b/include/linux/topology.h
index fbaa8774a431..10df2542653b 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -61,4 +61,76 @@ static inline int __next_node_with_cpus(int node)
 #define PENALTY_FOR_NODE_WITH_CPUS	(1)
 #endif
 
+/*
+ * Below are the 3 major initializers used in building sched_domains:
+ * SD_SIBLING_INIT, for SMT domains
+ * SD_CPU_INIT, for SMP domains
+ * SD_NODE_INIT, for NUMA domains
+ *
+ * Any architecture that cares to do any tuning to these values should do so
+ * by defining their own arch-specific initializer in include/asm/topology.h.
+ * A definition there will automagically override these default initializers
+ * and allow arch-specific performance tuning of sched_domains.
+ */
+#ifdef CONFIG_SCHED_SMT
+/* MCD - Do we really need this?  It is always on if CONFIG_SCHED_SMT is,
+ * so can't we drop this in favor of CONFIG_SCHED_SMT?
+ */
+#define ARCH_HAS_SCHED_WAKE_IDLE
+/* Common values for SMT siblings */
+#ifndef SD_SIBLING_INIT
+#define SD_SIBLING_INIT (struct sched_domain) {		\
+	.span			= CPU_MASK_NONE,	\
+	.parent			= NULL,			\
+	.groups			= NULL,			\
+	.min_interval		= 1,			\
+	.max_interval		= 2,			\
+	.busy_factor		= 8,			\
+	.imbalance_pct		= 110,			\
+	.cache_hot_time		= 0,			\
+	.cache_nice_tries	= 0,			\
+	.per_cpu_gain		= 25,			\
+	.flags			= SD_LOAD_BALANCE	\
+				| SD_BALANCE_NEWIDLE	\
+				| SD_BALANCE_EXEC	\
+				| SD_WAKE_AFFINE	\
+				| SD_WAKE_IDLE		\
+				| SD_SHARE_CPUPOWER,	\
+	.last_balance		= jiffies,		\
+	.balance_interval	= 1,			\
+	.nr_balance_failed	= 0,			\
+}
+#endif
+#endif /* CONFIG_SCHED_SMT */
+
+/* Common values for CPUs */
+#ifndef SD_CPU_INIT
+#define SD_CPU_INIT (struct sched_domain) {		\
+	.span			= CPU_MASK_NONE,	\
+	.parent			= NULL,			\
+	.groups			= NULL,			\
+	.min_interval		= 1,			\
+	.max_interval		= 4,			\
+	.busy_factor		= 64,			\
+	.imbalance_pct		= 125,			\
+	.cache_hot_time		= (5*1000/2),		\
+	.cache_nice_tries	= 1,			\
+	.per_cpu_gain		= 100,			\
+	.flags			= SD_LOAD_BALANCE	\
+				| SD_BALANCE_NEWIDLE	\
+				| SD_BALANCE_EXEC	\
+				| SD_WAKE_AFFINE	\
+				| SD_WAKE_BALANCE,	\
+	.last_balance		= jiffies,		\
+	.balance_interval	= 1,			\
+	.nr_balance_failed	= 0,			\
+}
+#endif
+
+#ifdef CONFIG_NUMA
+#ifndef SD_NODE_INIT
+#error Please define an appropriate SD_NODE_INIT in include/asm/topology.h!!!
+#endif
+#endif /* CONFIG_NUMA */
+
 #endif /* _LINUX_TOPOLOGY_H */