[patch 03/28] cpu alloc: IA64 support

[Christoph Lameter <clameter@sgi.com>]

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Typical use of per cpu memory for a small system of 8G 8p 4node is less than
64k per cpu memory. This is increasing rapidly for larger systems where we can
get up to 512k or 1M of memory used for cpu storage.

The maximum size of the cpu area is 128MB of memory.

The cpu area is placed in region 5 with the kernel, vmemmap and vmalloc areas.
So with this version we are limited to PAGE_SIZEd mappings. The cpu area and the
vmemmap area could use a large TLB size.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 arch/ia64/Kconfig          |   19 +++++++++++++++++++
 include/asm-ia64/pgtable.h |   27 +++++++++++++++++++++------
 2 files changed, 40 insertions(+), 6 deletions(-)

Index: linux-2.6/include/asm-ia64/pgtable.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/pgtable.h	2007-11-06 06:11:58.000000000 +0000
+++ linux-2.6/include/asm-ia64/pgtable.h	2007-11-06 06:28:37.000000000 +0000
@@ -224,21 +224,41 @@
  */
 
 
+/*
+ * Layout of the RGN_GAGE
+ *
+ * 47 bits wide (16kb pages)
+ *
+ * 0xa000000000000000-0xa00000200000000	8G	Kernel data area
+ * 0xa000002000000000-0xa00040000000000	64T	vmalloc
+ * 0xa000400000000000-0xa00060000000000 32T	vmemmmap
+ * 0xa000600000000000-0xa00080000000000	32T	cpu area
+ *
+ * 55 bits wide (64kb pages)
+ *
+ * 0xa000000000000000-0xa00000200000000	8G	Kernel data area
+ * 0xa000002000000000-0xa04000000000000	16P	vmalloc
+ * 0xa040000000000000-0xa06000000000000 8P	vmemmmap
+ * 0xa060000000000000-0xa08000000000000	8P	cpu area
+ */
+
 #define VMALLOC_START		(RGN_BASE(RGN_GATE) + 0x200000000UL)
+#define VMALLOC_END_INIT	(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 10)))
+
 #ifdef CONFIG_VIRTUAL_MEM_MAP
-# define VMALLOC_END_INIT	(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 9)))
 # define VMALLOC_END		vmalloc_end
   extern unsigned long vmalloc_end;
 #else
+# define VMALLOC_END VMALLOC_END_INIT
+#endif
+
 #if defined(CONFIG_SPARSEMEM) && defined(CONFIG_SPARSEMEM_VMEMMAP)
 /* SPARSEMEM_VMEMMAP uses half of vmalloc... */
-# define VMALLOC_END		(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 10)))
-# define vmemmap		((struct page *)VMALLOC_END)
-#else
-# define VMALLOC_END		(RGN_BASE(RGN_GATE) + (1UL << (4*PAGE_SHIFT - 9)))
-#endif
+# define vmemmap		((struct page *)VMALLOC_END_INIT)
 #endif
 
+#define CPU_AREA_BASE		(RGN_BASE(RGN_GATE) + (3UL << (4*PAGE_SHIFT - 11)))
+
 /* fs/proc/kcore.c */
 #define	kc_vaddr_to_offset(v) ((v) - RGN_BASE(RGN_GATE))
 #define	kc_offset_to_vaddr(o) ((o) + RGN_BASE(RGN_GATE))
Index: linux-2.6/arch/ia64/Kconfig
===================================================================
--- linux-2.6.orig/arch/ia64/Kconfig	2007-11-06 06:11:57.000000000 +0000
+++ linux-2.6/arch/ia64/Kconfig	2007-11-06 06:12:27.000000000 +0000
@@ -99,6 +99,25 @@
 	bool
 	default y
 
+config CPU_AREA_VIRTUAL
+	bool
+	default y
+
+# Maximum of 128 MB cpu_alloc space per cpu
+config CPU_AREA_ORDER
+	int
+	default "13"
+
+#
+# Expand the area in PAGE_SIZE steps. We could be using
+# huge pages if we would move this into region 5. But with the move
+# to 64k we will likely be fine here. 64k is more than enough
+# for most configurations.
+#
+config CPU_AREA_ALLOC_ORDER
+	int
+	default "0"
+
 choice
 	prompt "System type"
 	default IA64_GENERIC

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