[Xen-devel] [PATCH] 6/7 xen: Add basic NUMA support - Physinfo nr_cpus

[Ryan Harper <ryanh@xxxxxxxxxx>]

This patch adds a new field to physinfo, nr_cpus, which previously has
been calculated by the following formula:

nr_cpus = nr_nodes * sockets_per_node * cores_per_socket * \
          threads_per_core

This formula makes an assumption about the symmetry of NUMA nodes.  For
instance, on my Dual Opteron, which is a two node system with one cpu in
each node, sockets_per_node is calculated as 2, but this is incorrect.
There isn't a single value for sockets per node, but rather, it should
be a list of values, which is generated by taking the Hamming weight of
each node's cpumask.

In Xen, there aren't a large number of uses for sockets_per_node other
than calculating the number of cpus booted in the hypervisor.  Instead
of dealing with making another array in physinfo, I've opted to add
nr_cpus which is based on num_online_cpus() and replaced all instances
of the nr_cpus formula with a reference to the proper nr_cpus value that
is now contained in the physinfo.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@xxxxxxxxxx


diffstat output:
 tools/python/xen/lowlevel/xc/xc.c |    3 ++-
 tools/python/xen/xend/XendNode.py |    4 ----
 tools/xenmon/xenbaked.c           |    5 +----
 tools/xentrace/xentrace.c         |    5 +----
 xen/arch/ia64/xen/dom0_ops.c      |    1 +
 xen/arch/x86/dom0_ops.c           |    1 +
 xen/include/public/dom0_ops.h     |    1 +
 7 files changed, 7 insertions(+), 13 deletions(-)

Signed-off-by: Ryan Harper <ryanh@xxxxxxxxxx>
Signed-off-by: Ryan Grimm <grimm@xxxxxxxxxx>
---
diff -r 398a0cdf3e31 -r f9779dd3e52b tools/python/xen/lowlevel/xc/xc.c
--- a/tools/python/xen/lowlevel/xc/xc.c Fri Dec 16 17:02:16 2005
+++ b/tools/python/xen/lowlevel/xc/xc.c Fri Dec 16 17:47:48 2005
@@ -623,10 +623,11 @@
     if(q>cpu_cap)
         *(q-1)=0;
     
-    ret_obj = Py_BuildValue("{s:i,s:i,s:i,s:l,s:l,s:i,s:s}",
+    ret_obj = Py_BuildValue("{s:i,s:i,s:i,s:i,s:l,s:l,s:i,s:s}",
                          "threads_per_core", info.threads_per_core,
                          "cores_per_socket", info.cores_per_socket,
                          "sockets_per_node", info.sockets_per_node,
+                         "nr_cpus"         , info.nr_cpus,
                          "total_memory",     pages_to_mb(info.total_pages),
                          "free_memory",      pages_to_mb(info.free_pages),
                          "cpu_khz",          info.cpu_khz,
diff -r 398a0cdf3e31 -r f9779dd3e52b tools/python/xen/xend/XendNode.py
--- a/tools/python/xen/xend/XendNode.py Fri Dec 16 17:02:16 2005
+++ b/tools/python/xen/xend/XendNode.py Fri Dec 16 17:47:48 2005
@@ -122,10 +122,6 @@
     def physinfo(self):
         info = self.xc.physinfo()
 
-        info['nr_cpus'] = (info['nr_nodes'] *
-                           info['sockets_per_node'] *
-                           info['cores_per_socket'] *
-                           info['threads_per_core'])
         info['cpu_mhz'] = info['cpu_khz'] / 1000
         info['mem_chunks'] = self.format_memchunks(info)
         info['node_to_cpu'] = self.format_node_to_cpu(info)
diff -r 398a0cdf3e31 -r f9779dd3e52b tools/xenmon/xenbaked.c
--- a/tools/xenmon/xenbaked.c   Fri Dec 16 17:02:16 2005
+++ b/tools/xenmon/xenbaked.c   Fri Dec 16 17:47:48 2005
@@ -399,10 +399,7 @@
     xc_interface_close(xc_handle);
     opts.cpu_freq = (double)op.u.physinfo.cpu_khz/1000.0;
 
-    return (op.u.physinfo.threads_per_core *
-            op.u.physinfo.cores_per_socket *
-            op.u.physinfo.sockets_per_node *
-            op.u.physinfo.nr_nodes);
+    return op.u.physinfo.nr_cpus;
 }
 
 
diff -r 398a0cdf3e31 -r f9779dd3e52b tools/xentrace/xentrace.c
--- a/tools/xentrace/xentrace.c Fri Dec 16 17:02:16 2005
+++ b/tools/xentrace/xentrace.c Fri Dec 16 17:47:48 2005
@@ -277,10 +277,7 @@
 
     xc_interface_close(xc_handle);
 
-    return (op.u.physinfo.threads_per_core *
-            op.u.physinfo.cores_per_socket *
-            op.u.physinfo.sockets_per_node *
-            op.u.physinfo.nr_nodes);
+    return op.u.physinfo.nr_cpus;
 }
 
 
diff -r 398a0cdf3e31 -r f9779dd3e52b xen/arch/ia64/xen/dom0_ops.c
--- a/xen/arch/ia64/xen/dom0_ops.c      Fri Dec 16 17:02:16 2005
+++ b/xen/arch/ia64/xen/dom0_ops.c      Fri Dec 16 17:47:48 2005
@@ -204,6 +204,7 @@
         pi->sockets_per_node = 
             num_online_cpus() / (pi->threads_per_core * pi->cores_per_socket);
         pi->nr_nodes         = 1;
+        pi->nr_cpus          = (u32)num_online_cpus();
         pi->total_pages      = 99;  // FIXME
         pi->free_pages       = avail_domheap_pages();
         pi->cpu_khz          = 100;  // FIXME cpu_khz;
diff -r 398a0cdf3e31 -r f9779dd3e52b xen/arch/x86/dom0_ops.c
--- a/xen/arch/x86/dom0_ops.c   Fri Dec 16 17:02:16 2005
+++ b/xen/arch/x86/dom0_ops.c   Fri Dec 16 17:47:48 2005
@@ -188,6 +188,7 @@
         pi->cores_per_socket = boot_cpu_data.x86_num_cores;
         pi->sockets_per_node = 
             num_online_cpus() / (pi->threads_per_core * pi->cores_per_socket);
+        pi->nr_cpus          = (u32)num_online_cpus();
         pi->total_pages      = total_pages;
         pi->free_pages       = avail_domheap_pages();
         pi->cpu_khz          = cpu_khz;
diff -r 398a0cdf3e31 -r f9779dd3e52b xen/include/public/dom0_ops.h
--- a/xen/include/public/dom0_ops.h     Fri Dec 16 17:02:16 2005
+++ b/xen/include/public/dom0_ops.h     Fri Dec 16 17:47:48 2005
@@ -200,6 +200,7 @@
     uint32_t cores_per_socket;
     uint32_t sockets_per_node;
     uint32_t nr_nodes;
+    uint32_t nr_cpus;
     uint32_t cpu_khz;
     unsigned long total_pages;
     unsigned long free_pages;

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