[patch -mm 1/5] x86_64: configurable fake numa node sizes

[David Rientjes <rientjes@cs.washington.edu>]

Extends the numa=fake x86_64 command-line option to allow for configurable
node sizes.  These nodes can be used in conjunction with cpusets for
coarse memory resource management.

The old command-line option is still supported:
  numa=fake=32	gives 32 fake NUMA nodes, ignoring the NUMA setup of the
		actual machine.

But now you may configure your system for the node sizes of your choice:
  numa=fake=2*512,1024,2*256
		gives two 512M nodes, one 1024M node, two 256M nodes, and
		the rest of system memory to a sixth node.

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: David Rientjes <rientjes@cs.washington.edu>
---
 Documentation/x86_64/boot-options.txt |    9 +-
 arch/x86_64/mm/numa.c                 |  249 +++++++++++++++++++--------------
 include/asm-x86_64/mmzone.h           |    2 +-
 3 files changed, 150 insertions(+), 110 deletions(-)

diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt
index 625a21d..6ccdb5e 100644
--- a/Documentation/x86_64/boot-options.txt
+++ b/Documentation/x86_64/boot-options.txt
@@ -149,7 +149,14 @@ NUMA
 
   numa=noacpi   Don't parse the SRAT table for NUMA setup
 
-  numa=fake=X   Fake X nodes and ignore NUMA setup of the actual machine.
+  numa=fake=CMDLINE
+		If a number, fakes CMDLINE nodes and ignores NUMA setup of the
+		actual machine.  Otherwise, system memory is configured
+		depending on the sizes and coefficients listed.  For example:
+			numa=fake=2*512,1024,4*256
+		gives two 512M nodes, a 1024M node, and four 256M nodes.  If
+		the last character of CMDLINE is a comma, the remaining system
+		memory is not allocated to an additional node.
 
   numa=hotadd=percent
 		Only allow hotadd memory to preallocate page structures upto
diff --git a/arch/x86_64/mm/numa.c b/arch/x86_64/mm/numa.c
index 9ff3141..0417921 100644
--- a/arch/x86_64/mm/numa.c
+++ b/arch/x86_64/mm/numa.c
@@ -276,125 +276,160 @@ void __init numa_init_array(void)
 
 #ifdef CONFIG_NUMA_EMU
 /* Numa emulation */
-int numa_fake __initdata = 0;
+#define E820_ADDR_HOLE_SIZE(start, end)					\
+	(e820_hole_size((start) >> PAGE_SHIFT, (end) >> PAGE_SHIFT) <<	\
+	PAGE_SHIFT)
+char *cmdline __initdata;
 
 /*
- * This function is used to find out if the start and end correspond to
- * different zones.
+ * Setups up nid to range from addr to addr + size.  If the end boundary is
+ * greater than max_addr, then max_addr is used instead.  The return value is 0
+ * if there is additional memory left for allocation past addr and -1 otherwise.
+ * addr is adjusted to be at the end of the node.
  */
-int zone_cross_over(unsigned long start, unsigned long end)
+static int setup_node_range(int nid, struct bootnode *nodes, u64 *addr,
+			    u64 size, u64 max_addr)
 {
-	if ((start < (MAX_DMA32_PFN << PAGE_SHIFT)) &&
-			(end >= (MAX_DMA32_PFN << PAGE_SHIFT)))
-		return 1;
-	return 0;
+	int ret = 0;
+	nodes[nid].start = *addr;
+	*addr += size;
+	if (*addr >= max_addr) {
+		*addr = max_addr;
+		ret = -1;
+	}
+	nodes[nid].end = *addr;
+	node_set_online(nid);
+	printk(KERN_INFO "Faking node %d at %016Lx-%016Lx (%LuMB)\n", nid,
+	       nodes[nid].start, nodes[nid].end,
+	       (nodes[nid].end - nodes[nid].start) >> 20);
+	return ret;
 }
 
-static int __init numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
+/*
+ * Splits num_nodes nodes up equally starting at node_start.  The return value
+ * is the number of nodes split up and addr is adjusted to be at the end of the
+ * last node allocated.
+ */
+static int split_nodes_equally(struct bootnode *nodes, u64 *addr, u64 max_addr,
+			       int node_start, int num_nodes)
 {
- 	int i, big;
- 	struct bootnode nodes[MAX_NUMNODES];
- 	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 */
-
-	old_sz = sz;
-	/*
-	 * Round down to the nearest FAKE_NODE_MIN_SIZE.
-	 */
-	sz &= FAKE_NODE_MIN_HASH_MASK;
+	unsigned int big;
+	u64 size;
+	int i;
 
+	if (num_nodes <= 0)
+		return -1;
+	if (num_nodes > MAX_NUMNODES)
+		num_nodes = MAX_NUMNODES;
+	size = (max_addr - *addr - E820_ADDR_HOLE_SIZE(*addr, max_addr)) /
+	       num_nodes;
 	/*
-	 * We ensure that each node is at least 64MB big.  Smaller than this
-	 * size can cause VM hiccups.
+	 * Calculate the number of big nodes that can be allocated as a result
+	 * of consolidating the leftovers.
 	 */
-	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) / FAKE_NODE_MIN_SIZE;
-		printk(KERN_INFO "Number of fake nodes will be = %d\n",
-				numa_fake);
-		sz = FAKE_NODE_MIN_SIZE;
+	big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * num_nodes) /
+	      FAKE_NODE_MIN_SIZE;
+
+	/* Round down to nearest FAKE_NODE_MIN_SIZE. */
+	size &= FAKE_NODE_MIN_HASH_MASK;
+	if (!size) {
+		printk(KERN_ERR "Not enough memory for each node.  "
+		       "NUMA emulation disabled.\n");
+		return -1;
 	}
-	/*
-	 * 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) / 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(&nodes,0,sizeof(nodes));
-	end = start;
- 	for (i = 0; i < numa_fake; i++) {
-		/*
-		 * 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) {
-			numa_fake = i - 1;
-			break;
-		}
- 		start = nodes[i].start = end;
-		/*
-		 * Final node can have all the remaining memory.
-		 */
- 		if (i == numa_fake-1)
- 			sz = max_addr - start;
- 		end = nodes[i].start + sz;
-		/*
-		 * Fir "big" number of nodes get extra granule.
-		 */
+
+	for (i = node_start; i < num_nodes + node_start; i++) {
+		u64 end = *addr + size;
 		if (i < big)
 			end += FAKE_NODE_MIN_SIZE;
 		/*
-		 * Iterate over the range to ensure that this node gets at
-		 * least sz amount of RAM (excluding holes)
+		 * The final node can have the remaining system RAM.  Other
+		 * nodes receive roughly the same amount of available pages.
 		 */
-		while ((end - start - e820_hole_size(start, end)) < sz) {
-			end += FAKE_NODE_MIN_SIZE;
-			if (end >= max_addr)
-				break;
+		if (i == num_nodes + node_start - 1)
+			end = max_addr;
+		else
+			while (end - *addr - E820_ADDR_HOLE_SIZE(*addr, end) <
+			       size)
+				end += FAKE_NODE_MIN_SIZE;
+		if (setup_node_range(i, nodes, addr, end - *addr, max_addr) < 0)
+			break;
+	}
+	return i - node_start + 1;
+}
+
+/*
+ * Sets up the system RAM area from start_pfn to end_pfn according to the
+ * numa=fake command-line option.
+ */
+static int __init numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
+{
+ 	struct bootnode nodes[MAX_NUMNODES];
+	u64 addr = start_pfn << PAGE_SHIFT;
+	u64 max_addr = end_pfn << PAGE_SHIFT;
+	unsigned int coeff;
+	unsigned int num = 0;
+	int num_nodes = 0;
+	u64 size;
+	int i;
+
+	memset(&nodes, 0, sizeof(nodes));
+	/*
+	 * If the numa=fake command-line is just a single number N, split the
+	 * system RAM into N fake nodes.
+	 */
+	if (!strchr(cmdline, '*') && !strchr(cmdline, ',')) {
+		num_nodes = split_nodes_equally(nodes, &addr, max_addr, 0,
+						simple_strtol(cmdline, NULL, 0));
+		if (num_nodes < 0)
+			return num_nodes;
+		goto out;
+	}
+
+	/* Parse the command line. */
+	for (coeff = 1; ; cmdline++) {
+		if (*cmdline && isdigit(*cmdline)) {
+			num = num * 10 + *cmdline - '0';
+			continue;
 		}
-		/*
-		 * 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 hole.
-		 */
-		while (e820_hole_size(end, end + FAKE_NODE_MIN_SIZE) > 0) {
-			if (zone_cross_over(start, end + sz)) {
-				end = (MAX_DMA32_PFN << PAGE_SHIFT);
-				break;
+		if (*cmdline == '*')
+			coeff = num;
+		if (!*cmdline || *cmdline == ',') {
+			/*
+			 * Round down to the nearest FAKE_NODE_MIN_SIZE.
+			 * Command-line coefficients are in megabytes.
+			 */
+			size = (num << 20) & FAKE_NODE_MIN_HASH_MASK;
+			if (size) {
+				for (i = 0; i < coeff; i++, num_nodes++)
+					if (setup_node_range(num_nodes, nodes,
+						&addr, size, max_addr) < 0)
+						goto done;
+				coeff = 1;
 			}
-			if (end >= max_addr)
-				break;
-			end += FAKE_NODE_MIN_SIZE;
 		}
-		if (end > max_addr)
-			end = max_addr;
-		nodes[i].end = end;
- 		printk(KERN_INFO "Faking node %d at %016Lx-%016Lx (%LuMB)\n",
- 		       i,
- 		       nodes[i].start, nodes[i].end,
- 		       (nodes[i].end - nodes[i].start) >> 20);
-		node_set_online(i);
- 	}
- 	memnode_shift = compute_hash_shift(nodes, numa_fake);
- 	if (memnode_shift < 0) {
- 		memnode_shift = 0;
- 		printk(KERN_ERR "No NUMA hash function found. Emulation disabled.\n");
- 		return -1;
- 	}
- 	for_each_online_node(i) {
+		if (!*cmdline)
+			break;
+		num = 0;
+	}
+done:
+	if (!num_nodes)
+		return -1;
+	/* Fill remainder of system RAM with a final node, if appropriate. */
+	if (addr < max_addr && *(cmdline - 1) != ',') {
+		setup_node_range(num_nodes, nodes, &addr, max_addr - addr,
+				 max_addr);
+		num_nodes++;
+	}
+out:
+	memnode_shift = compute_hash_shift(nodes, num_nodes);
+	if (memnode_shift < 0) {
+		memnode_shift = 0;
+		printk(KERN_ERR "No NUMA hash function found.  NUMA emulation "
+		       "disabled.\n");
+		return -1;
+	}
+	for_each_online_node(i) {
 		e820_register_active_regions(i, nodes[i].start >> PAGE_SHIFT,
 						nodes[i].end >> PAGE_SHIFT);
  		setup_node_bootmem(i, nodes[i].start, nodes[i].end);
@@ -402,14 +437,15 @@ static int __init numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
  	numa_init_array();
  	return 0;
 }
-#endif
+#undef E820_ADDR_HOLE_SIZE
+#endif /* CONFIG_NUMA_EMU */
 
 void __init numa_initmem_init(unsigned long start_pfn, unsigned long end_pfn)
 { 
 	int i;
 
 #ifdef CONFIG_NUMA_EMU
-	if (numa_fake && !numa_emulation(start_pfn, end_pfn))
+	if (cmdline && !numa_emulation(start_pfn, end_pfn))
  		return;
 #endif
 
@@ -502,11 +538,8 @@ static __init int numa_setup(char *opt)
 	if (!strncmp(opt,"off",3))
 		numa_off = 1;
 #ifdef CONFIG_NUMA_EMU
-	if(!strncmp(opt, "fake=", 5)) {
-		numa_fake = simple_strtoul(opt+5,NULL,0); ;
-		if (numa_fake >= MAX_NUMNODES)
-			numa_fake = MAX_NUMNODES;
-	}
+	if (!strncmp(opt, "fake=", 5))
+		cmdline = opt + 5;
 #endif
 #ifdef CONFIG_ACPI_NUMA
  	if (!strncmp(opt,"noacpi",6))
diff --git a/include/asm-x86_64/mmzone.h b/include/asm-x86_64/mmzone.h
index fb558fb..19a8937 100644
--- a/include/asm-x86_64/mmzone.h
+++ b/include/asm-x86_64/mmzone.h
@@ -49,7 +49,7 @@ extern int pfn_valid(unsigned long pfn);
 
 #ifdef CONFIG_NUMA_EMU
 #define FAKE_NODE_MIN_SIZE	(64*1024*1024)
-#define FAKE_NODE_MIN_HASH_MASK	(~(FAKE_NODE_MIN_SIZE - 1ul))
+#define FAKE_NODE_MIN_HASH_MASK	(~(FAKE_NODE_MIN_SIZE - 1uL))
 #endif
 
 #endif
-
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