diff mbox

[RFC,1/3] ARM: mm: Add discontiguous memory support.

Message ID 1355334049-10247-2-git-send-email-steve.capper@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Steve Capper Dec. 12, 2012, 5:40 p.m. UTC 
This patch adds support for discontiguous memory, with a view to
each discontiguous block being assigned to a NUMA node (in a future
patch).

Discontiguous memory should only be used to back NUMA on systems
where sparse memory is not available.

Signed-off-by: Steve Capper <steve.capper@arm.com>
---
 arch/arm/Kconfig              |   15 +++++++++++++
 arch/arm/include/asm/mmzone.h |   37 ++++++++++++++++++++++++++++++
 arch/arm/mm/Makefile          |    2 ++
 arch/arm/mm/init.c            |    9 ++++++++
 arch/arm/mm/numa.c            |   50 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 113 insertions(+)
 create mode 100644 arch/arm/include/asm/mmzone.h
 create mode 100644 arch/arm/mm/numa.c

Comments

Russell King - ARM Linux Dec. 12, 2012, 6:01 p.m. UTC | #1 
On Wed, Dec 12, 2012 at 05:40:47PM +0000, Steve Capper wrote:
> This patch adds support for discontiguous memory, with a view to
> each discontiguous block being assigned to a NUMA node (in a future
> patch).
> 
> Discontiguous memory should only be used to back NUMA on systems
> where sparse memory is not available.

Err, we had this, and then we ripped it all out.  Do we have any NUMA ARM
systems?  I don't think we do.
Steve Capper Dec. 13, 2012, 1:13 p.m. UTC | #2 
On Wed, Dec 12, 2012 at 06:01:21PM +0000, Russell King - ARM Linux wrote:
> On Wed, Dec 12, 2012 at 05:40:47PM +0000, Steve Capper wrote:
> > This patch adds support for discontiguous memory, with a view to
> > each discontiguous block being assigned to a NUMA node (in a future
> > patch).
> > 
> > Discontiguous memory should only be used to back NUMA on systems
> > where sparse memory is not available.
> 
> Err, we had this, and then we ripped it all out.  Do we have any NUMA ARM
> systems?  I don't think we do.

Hi Russell,
There aren't any ARM NUMA systems out at the moment, but the Linux NUMA
subsystem can be used to group cores that share an L2 cache together into the
same node. This can then potentially reduce the L3 traffic required to run
certain tasks, as the scheduler has a notion of memory topology that matches
the cache topology. (An example platform where this can be beneficial is the TC2).

Best,
diff mbox

Patch

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9759fec..9846d89 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1159,8 +1159,23 @@  config ARM_TIMER_SP804
 	select CLKSRC_MMIO
 	select HAVE_SCHED_CLOCK
 
+config ARCH_FLATMEM_ENABLE
+	bool
+	depends on MMU
+	default y
+
+config ARCH_DISCONTIGMEM_ENABLE
+	bool
+	depends on MMU
+	default y
+
 source arch/arm/mm/Kconfig
 
+config NUMA_ALLOC_NODES
+	bool
+	depends on DISCONTIGMEM
+	default y
+
 config ARM_NR_BANKS
 	int
 	default 16 if ARCH_EP93XX
diff --git a/arch/arm/include/asm/mmzone.h b/arch/arm/include/asm/mmzone.h
new file mode 100644
index 0000000..f6d7337
--- /dev/null
+++ b/arch/arm/include/asm/mmzone.h
@@ -0,0 +1,37 @@ 
+/*
+ * Discontiguous memory and NUMA support, based on the PowerPC implementation.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef __ASM_ARM_MMZONE_H_
+#define __ASM_ARM_MMZONE_H_
+#ifdef __KERNEL__
+
+#include <linux/cpumask.h>
+
+#ifdef CONFIG_NUMA_ALLOC_NODES
+#define NODE_DATA(nid)		(node_data[nid])
+extern void __init arm_numa_alloc_nodes(unsigned long max_low);
+extern struct pglist_data *node_data[];
+#else
+#define arm_numa_alloc_nodes(_mlow)	do {} while (0)
+#endif
+
+#define	pfn_to_nid(pfn)		(0)
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_ARM_MMZONE_H_ */
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 8a9c4cb..57a7055 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -96,3 +96,5 @@  obj-$(CONFIG_CACHE_FEROCEON_L2)	+= cache-feroceon-l2.o
 obj-$(CONFIG_CACHE_L2X0)	+= cache-l2x0.o
 obj-$(CONFIG_CACHE_XSC3L2)	+= cache-xsc3l2.o
 obj-$(CONFIG_CACHE_TAUROS2)	+= cache-tauros2.o
+
+obj-$(CONFIG_NUMA_ALLOC_NODES)	+= numa.o
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index abe4eae..98488ee 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -33,6 +33,7 @@ 
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
+#include <asm/mmzone.h>
 
 #include "mm.h"
 
@@ -178,6 +179,12 @@  static void __init arm_bootmem_init(unsigned long start_pfn,
 	pg_data_t *pgdat;
 
 	/*
+	 * If we have NUMA or discontiguous memory, allocate the required
+	 * nodes by reserving memblocks.
+	 */
+	arm_numa_alloc_nodes(end_pfn);
+
+	/*
 	 * Allocate the bootmem bitmap page.  This must be in a region
 	 * of memory which has already been mapped.
 	 */
@@ -620,7 +627,9 @@  void __init mem_init(void)
 	extern u32 itcm_end;
 #endif
 
+#ifdef CONFIG_FLATMEM
 	max_mapnr   = pfn_to_page(max_pfn + PHYS_PFN_OFFSET) - mem_map;
+#endif
 
 	/* this will put all unused low memory onto the freelists */
 	free_unused_memmap(&meminfo);
diff --git a/arch/arm/mm/numa.c b/arch/arm/mm/numa.c
new file mode 100644
index 0000000..5141134
--- /dev/null
+++ b/arch/arm/mm/numa.c
@@ -0,0 +1,50 @@ 
+/*
+ * Discontiguous memory and NUMA support, based on the PowerPC implementation.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/nodemask.h>
+#include <linux/bootmem.h>
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/node.h>
+#include <linux/cpu.h>
+#include <linux/memblock.h>
+
+#include <asm/string.h>
+#include <asm/mmzone.h>
+#include <asm/setup.h>
+
+struct pglist_data *node_data[MAX_NUMNODES];
+EXPORT_SYMBOL(node_data);
+
+static unsigned int numa_node_count = 1;
+
+void __init arm_numa_alloc_nodes(unsigned long max_low)
+{
+	int node;
+
+	for (node = 0; node < numa_node_count; node++) {
+		phys_addr_t pa = memblock_alloc_base(sizeof(pg_data_t),
+				L1_CACHE_BYTES, __pfn_to_phys(max_low));
+
+		NODE_DATA(node) = __va(pa);
+		memset(NODE_DATA(node), 0, sizeof(pg_data_t));
+		NODE_DATA(node)->bdata = &bootmem_node_data[node];
+	}
+}