[POWERPC] Fake NUMA emulation for PowerPC

Here's a dumb simple implementation of fake NUMA nodes for PowerPC.
Fake NUMA nodes can be specified using the following command line option

numa=fake=<node range>

node range is of the format <range1>,<range2>,...<rangeN>

Each of the rangeX parameters is passed using memparse().  I find this
useful for fake NUMA emulation on my simple PowerPC machine.  I've
tested it on a non-numa box with the following arguments:

numa=fake=1G
numa=fake=1G,2G
name=fake=1G,512M,2G
numa=fake=1500M,2800M mem=3500M
numa=fake=1G mem=512M
numa=fake=1G mem=1G

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 54 insertions, 5 deletions

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index c12adc3ddffd..1666e7d54cca 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -24,6 +24,8 @@
 
 static int numa_enabled = 1;
 
+static char *cmdline __initdata;
+
 static int numa_debug;
 #define dbg(args...) if (numa_debug) { printk(KERN_INFO args); }
 
@@ -39,6 +41,43 @@ static bootmem_data_t __initdata plat_node_bdata[MAX_NUMNODES];
 static int min_common_depth;
 static int n_mem_addr_cells, n_mem_size_cells;
 
+static int __cpuinit fake_numa_create_new_node(unsigned long end_pfn,
+                                                unsigned int *nid)
+{
+        unsigned long long mem;
+        char *p = cmdline;
+        static unsigned int fake_nid = 0;
+        static unsigned long long curr_boundary = 0;
+
+        *nid = fake_nid;
+        if (!p)
+                return 0;
+
+        mem = memparse(p, &p);
+        if (!mem)
+                return 0;
+
+        if (mem < curr_boundary)
+                return 0;
+
+        curr_boundary = mem;
+
+        if ((end_pfn << PAGE_SHIFT) > mem) {
+                /*
+                 * Skip commas and spaces
+                 */
+                while (*p == ',' || *p == ' ' || *p == '\t')
+                        p++;
+
+                cmdline = p;
+                fake_nid++;
+                *nid = fake_nid;
+                dbg("created new fake_node with id %d\n", fake_nid);
+                return 1;
+        }
+        return 0;
+}
+
 static void __cpuinit map_cpu_to_node(int cpu, int node)
 {
         numa_cpu_lookup_table[cpu] = node;
@@ -344,12 +383,14 @@ static void __init parse_drconf_memory(struct device_node *memory)
                         if (nid == 0xffff || nid >= MAX_NUMNODES)
                                 nid = default_nid;
                 }
-                node_set_online(nid);
 
                 size = numa_enforce_memory_limit(start, lmb_size);
                 if (!size)
                         continue;
 
+                fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
+                node_set_online(nid);
+
                 add_active_range(nid, start >> PAGE_SHIFT,
                                  (start >> PAGE_SHIFT) + (size >> PAGE_SHIFT));
         }
@@ -429,7 +470,6 @@ new_range:
                 nid = of_node_to_nid_single(memory);
                 if (nid < 0)
                         nid = default_nid;
-                node_set_online(nid);
 
                 if (!(size = numa_enforce_memory_limit(start, size))) {
                         if (--ranges)
@@ -438,6 +478,9 @@ new_range:
                                 continue;
                 }
 
+                fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
+                node_set_online(nid);
+
                 add_active_range(nid, start >> PAGE_SHIFT,
                                 (start >> PAGE_SHIFT) + (size >> PAGE_SHIFT));
 
@@ -461,7 +504,7 @@ static void __init setup_nonnuma(void)
         unsigned long top_of_ram = lmb_end_of_DRAM();
         unsigned long total_ram = lmb_phys_mem_size();
         unsigned long start_pfn, end_pfn;
-        unsigned int i;
+        unsigned int i, nid = 0;
 
         printk(KERN_DEBUG "Top of RAM: 0x%lx, Total RAM: 0x%lx\n",
                top_of_ram, total_ram);
@@ -471,9 +514,11 @@ static void __init setup_nonnuma(void)
         for (i = 0; i < lmb.memory.cnt; ++i) {
                 start_pfn = lmb.memory.region[i].base >> PAGE_SHIFT;
                 end_pfn = start_pfn + lmb_size_pages(&lmb.memory, i);
-                add_active_range(0, start_pfn, end_pfn);
+
+                fake_numa_create_new_node(end_pfn, &nid);
+                add_active_range(nid, start_pfn, end_pfn);
+                node_set_online(nid);
         }
-        node_set_online(0);
 }
 
 void __init dump_numa_cpu_topology(void)
@@ -702,6 +747,10 @@ static int __init early_numa(char *p)
         if (strstr(p, "debug"))
                 numa_debug = 1;
 
+        p = strstr(p, "fake=");
+        if (p)
+                cmdline = p + strlen("fake=");
+
         return 0;
 }
 early_param("numa", early_numa);