[Patch]: fake numa for x86_64 machines with big IO hole.
This patch resolves the issue of running with numa=fake=X on kernel
command line on x86_64 machines that have big IO hole. While
calculating the size of each node now we look at the total hole size in
that range. Previously there were nodes that only had IO holes in them
causing kernel boot problems. We now use the NODE_MIN_SIZE (64MB) as
the minimum size of memory that any node must have. We reduce the
number of allocated nodes if the number of nodes specified on kernel
command line results in any node getting memory smaller than
NODE_MIN_SIZE. This change allows the extra memory to be incremented in
NODE_MIN_SIZE granule and uniformly distribute among as many nodes
(called big nodes) as possible.
Signed-off-by: David Rientjes <[EMAIL PROTECTED]>
Signed-off-by: Paul Menage <[EMAIL PROTECTED]>
Signed-off-by: Rohit Seth <[EMAIL PROTECTED]>
--- linux-2.6.20-rc1-mm1.org/include/asm-x86_64/mmzone.h2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/include/asm-x86_64/mmzone.h2006-12-28
16:00:17.0 -0800
@@ -47,5 +47,10 @@ static inline __attribute__((pure)) int
extern int pfn_valid(unsigned long pfn);
#endif
+#ifdef CONFIG_NUMA_EMU
+#define NODE_MIN_SIZE (64*1024*1024)
+#define NODE_MIN_HASH_MASK (~(NODE_MIN_SIZE - 1ul))
+#endif
+
#endif
#endif
--- linux-2.6.20-rc1-mm1.org/include/asm-x86_64/e820.h 2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/include/asm-x86_64/e820.h 2006-12-28
15:59:19.0 -0800
@@ -46,6 +46,7 @@ extern void e820_mark_nosave_regions(voi
extern void e820_print_map(char *who);
extern int e820_any_mapped(unsigned long start, unsigned long end, unsigned
type);
extern int e820_all_mapped(unsigned long start, unsigned long end, unsigned
type);
+extern unsigned long e820_hole_size(unsigned long start, unsigned long end);
extern void e820_setup_gap(void);
extern void e820_register_active_regions(int nid,
--- linux-2.6.20-rc1-mm1.org/arch/x86_64/mm/numa.c 2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/arch/x86_64/mm/numa.c 2006-12-28 16:02:07.0
-0800
@@ -275,31 +275,111 @@ void __init numa_init_array(void)
}
#ifdef CONFIG_NUMA_EMU
+/* Numa emulation */
int numa_fake __initdata = 0;
-/* Numa emulation */
+/*
+ * This function is used to find out if the start and end correspond to
+ * different zones.
+ */
+int zone_cross_over(unsigned long start, unsigned long end)
+{
+ if ((start < (MAX_DMA32_PFN << PAGE_SHIFT)) &&
+ (end >= (MAX_DMA32_PFN << PAGE_SHIFT)))
+ return 1;
+ return 0;
+}
+
static int __init numa_emulation(unsigned long start_pfn, unsigned long
end_pfn)
{
- int i;
+ int i, big;
struct bootnode nodes[MAX_NUMNODES];
- unsigned long sz = ((end_pfn - start_pfn)< 1) {
- unsigned long x = 1;
- while ((x << 1) < sz)
- x <<= 1;
- if (x < sz/2)
- printk(KERN_ERR "Numa emulation unbalanced. Complain to
maintainer\n");
- sz = x;
- }
+ old_sz = sz;
+ /*
+* Round down to the nearest NODE_MIN_SIZE.
+*/
+ sz &= NODE_MIN_HASH_MASK;
+
+ /*
+* We ensure that each node is at least 64MB big. Smaller than this
+* size can cause VM hiccups.
+*/
+ if (sz == 0) {
+ printk(KERN_INFO"Not enough memory for %d nodes. Reducing "
+ "the number of nodes\n", numa_fake);
+ numa_fake = (max_addr - start - hole_size) / NODE_MIN_SIZE;
+ printk(KERN_INFO"Number of fake nodes will be = %d\n",
numa_fake);
+ sz = NODE_MIN_SIZE;
+ }
+ /*
+* Find out how many nodes can get an extra NODE_MIN_SIZE granule.
+* This logic ensures the extra memory gets distributed among as many
+* nodes as possible (as compared to one single node getting all that
+* extra memory.
+*/
+ big = ((old_sz - sz) * numa_fake) / NODE_MIN_SIZE;
+ printk(KERN_INFO"Fake node Size: %luMB hole_size: %luMB big nodes:
%d\n",
+ (sz >> 20), (hole_size >> 20), big);
memset(,0,sizeof(nodes));
+ end = start;
for (i = 0; i < numa_fake; i++) {
- nodes[i].start = (start_pfn<= max_addr) {
+ numa_fake = i - 1;
+ break;
+ }
+ start = nodes[i].start = end;
+ /*
+* Final node can have all the remaining memory.
+*/
if (i == numa_fake-1)
- sz = (end_pfn<= max_addr)
+ break;
+ }
+ /*
+* Look at the next node to make sure there is some real memory
+* to map. Bad things happen when the only memory present
+* in a zone on a fake node is IO
[Patch]: fake numa for x86_64 machines with big IO hole.
This patch resolves the issue of running with numa=fake=X on kernel
command line on x86_64 machines that have big IO hole. While
calculating the size of each node now we look at the total hole size in
that range. Previously there were nodes that only had IO holes in them
causing kernel boot problems. We now use the NODE_MIN_SIZE (64MB) as
the minimum size of memory that any node must have. We reduce the
number of allocated nodes if the number of nodes specified on kernel
command line results in any node getting memory smaller than
NODE_MIN_SIZE. This change allows the extra memory to be incremented in
NODE_MIN_SIZE granule and uniformly distribute among as many nodes
(called big nodes) as possible.
Signed-off-by: David Rientjes [EMAIL PROTECTED]
Signed-off-by: Paul Menage [EMAIL PROTECTED]
Signed-off-by: Rohit Seth [EMAIL PROTECTED]
--- linux-2.6.20-rc1-mm1.org/include/asm-x86_64/mmzone.h2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/include/asm-x86_64/mmzone.h2006-12-28
16:00:17.0 -0800
@@ -47,5 +47,10 @@ static inline __attribute__((pure)) int
extern int pfn_valid(unsigned long pfn);
#endif
+#ifdef CONFIG_NUMA_EMU
+#define NODE_MIN_SIZE (64*1024*1024)
+#define NODE_MIN_HASH_MASK (~(NODE_MIN_SIZE - 1ul))
+#endif
+
#endif
#endif
--- linux-2.6.20-rc1-mm1.org/include/asm-x86_64/e820.h 2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/include/asm-x86_64/e820.h 2006-12-28
15:59:19.0 -0800
@@ -46,6 +46,7 @@ extern void e820_mark_nosave_regions(voi
extern void e820_print_map(char *who);
extern int e820_any_mapped(unsigned long start, unsigned long end, unsigned
type);
extern int e820_all_mapped(unsigned long start, unsigned long end, unsigned
type);
+extern unsigned long e820_hole_size(unsigned long start, unsigned long end);
extern void e820_setup_gap(void);
extern void e820_register_active_regions(int nid,
--- linux-2.6.20-rc1-mm1.org/arch/x86_64/mm/numa.c 2006-12-28
16:04:19.0 -0800
+++ linux-2.6.20-rc1-mm1/arch/x86_64/mm/numa.c 2006-12-28 16:02:07.0
-0800
@@ -275,31 +275,111 @@ void __init numa_init_array(void)
}
#ifdef CONFIG_NUMA_EMU
+/* Numa emulation */
int numa_fake __initdata = 0;
-/* Numa emulation */
+/*
+ * This function is used to find out if the start and end correspond to
+ * different zones.
+ */
+int zone_cross_over(unsigned long start, unsigned long end)
+{
+ if ((start (MAX_DMA32_PFN PAGE_SHIFT))
+ (end = (MAX_DMA32_PFN PAGE_SHIFT)))
+ return 1;
+ return 0;
+}
+
static int __init numa_emulation(unsigned long start_pfn, unsigned long
end_pfn)
{
- int i;
+ int i, big;
struct bootnode nodes[MAX_NUMNODES];
- unsigned long sz = ((end_pfn - start_pfn)PAGE_SHIFT) / numa_fake;
+ unsigned long sz, old_sz;
+ unsigned long hole_size;
+ unsigned long start, end;
+ unsigned long max_addr = (end_pfn PAGE_SHIFT);
+
+ start = (start_pfn PAGE_SHIFT);
+ hole_size = e820_hole_size(start, max_addr);
+ sz = (max_addr - start - hole_size) / numa_fake;
/* Kludge needed for the hash function */
- if (hweight64(sz) 1) {
- unsigned long x = 1;
- while ((x 1) sz)
- x = 1;
- if (x sz/2)
- printk(KERN_ERR Numa emulation unbalanced. Complain to
maintainer\n);
- sz = x;
- }
+ old_sz = sz;
+ /*
+* Round down to the nearest NODE_MIN_SIZE.
+*/
+ sz = NODE_MIN_HASH_MASK;
+
+ /*
+* We ensure that each node is at least 64MB big. Smaller than this
+* size can cause VM hiccups.
+*/
+ if (sz == 0) {
+ printk(KERN_INFONot enough memory for %d nodes. Reducing
+ the number of nodes\n, numa_fake);
+ numa_fake = (max_addr - start - hole_size) / NODE_MIN_SIZE;
+ printk(KERN_INFONumber of fake nodes will be = %d\n,
numa_fake);
+ sz = NODE_MIN_SIZE;
+ }
+ /*
+* Find out how many nodes can get an extra NODE_MIN_SIZE granule.
+* This logic ensures the extra memory gets distributed among as many
+* nodes as possible (as compared to one single node getting all that
+* extra memory.
+*/
+ big = ((old_sz - sz) * numa_fake) / NODE_MIN_SIZE;
+ printk(KERN_INFOFake node Size: %luMB hole_size: %luMB big nodes:
%d\n,
+ (sz 20), (hole_size 20), big);
memset(nodes,0,sizeof(nodes));
+ end = start;
for (i = 0; i numa_fake; i++) {
- nodes[i].start = (start_pfnPAGE_SHIFT) + i*sz;
+ /*
+* In case we are not able to allocate enough memory for all
+* the nodes, we reduce the number of fake nodes.
+*/
+ if (end = max_addr) {
+
