[PATCH] Export cpu topology in sysfs

The patch implements cpu topology exportation by sysfs.

Items (attributes) are similar to /proc/cpuinfo.

1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
	represent the physical package id of  cpu X;
2) /sys/devices/system/cpu/cpuX/topology/core_id:
	represent the cpu core id to cpu X;
3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
	represent the thread siblings to cpu X in the same core;
4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
	represent the thread siblings to cpu X in the same physical package;

To implement it in an architecture-neutral way, a new source file,
driver/base/topology.c, is to export the 5 attributes.

If one architecture wants to support this feature, it just needs to
implement 4 defines, typically in file include/asm-XXX/topology.h.
The 4 defines are:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
#define topology_core_siblings(cpu)

The type of **_id is int.
The type of siblings is cpumask_t.

To be consistent on all architectures, the 4 attributes should have
deafult values if their values are unavailable. Below is the rule.

1) physical_package_id: If cpu has no physical package id, -1 is the
default value.

2) core_id: If cpu doesn't support multi-core, its core id is 0.

3) thread_siblings: Just include itself, if the cpu doesn't support
HT/multi-thread.

4) core_siblings: Just include itself, if the cpu doesn't support
multi-core and HT/Multi-thread.

So be careful when declaring the 4 defines in include/asm-XXX/topology.h.

If an attribute isn't defined on an architecture, it won't be exported.

Thank Nathan, Greg, Andi, Paul and Venki.

The patch provides defines for i386/x86_64/ia64.

Signed-off-by: Zhang, Yanmin <yanmin.zhang@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 8 deletions

diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index 706b7734e191..6e5eea19fa67 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -71,31 +71,33 @@ static int __init topology_init(void)
         int i, err = 0;
 
 #ifdef CONFIG_NUMA
-        sysfs_nodes = kmalloc(sizeof(struct node) * MAX_NUMNODES, GFP_KERNEL);
+        sysfs_nodes = kzalloc(sizeof(struct node) * MAX_NUMNODES, GFP_KERNEL);
         if (!sysfs_nodes) {
                 err = -ENOMEM;
                 goto out;
         }
-        memset(sysfs_nodes, 0, sizeof(struct node) * MAX_NUMNODES);
 
-        /* MCD - Do we want to register all ONLINE nodes, or all POSSIBLE nodes? */
-        for_each_online_node(i)
+        /*
+         * MCD - Do we want to register all ONLINE nodes, or all POSSIBLE nodes?
+         */
+        for_each_online_node(i) {
                 if ((err = register_node(&sysfs_nodes[i], i, 0)))
                         goto out;
+        }
 #endif
 
-        sysfs_cpus = kmalloc(sizeof(struct ia64_cpu) * NR_CPUS, GFP_KERNEL);
+        sysfs_cpus = kzalloc(sizeof(struct ia64_cpu) * NR_CPUS, GFP_KERNEL);
         if (!sysfs_cpus) {
                 err = -ENOMEM;
                 goto out;
         }
-        memset(sysfs_cpus, 0, sizeof(struct ia64_cpu) * NR_CPUS);
 
-        for_each_present_cpu(i)
+        for_each_present_cpu(i) {
                 if((err = arch_register_cpu(i)))
                         goto out;
+        }
 out:
         return err;
 }
 
-__initcall(topology_init);
+subsys_initcall(topology_init);