Fix. Using sysfs file system entries to count the number of physical CPUs. Fall-back to "/proc/cpuinfo" included for backward-compatibility with legacy systems.

1 files changed, 39 insertions, 6 deletions

diff --git a/lib/facter/physicalprocessorcount.rb b/lib/facter/physicalprocessorcount.rb
index 9c59614..86d0749 100644
--- a/lib/facter/physicalprocessorcount.rb
+++ b/lib/facter/physicalprocessorcount.rb
@@ -3,16 +3,49 @@
 # Purpose: Return the number of physical processors.
 #
 # Resolution:
-#   On linux, parses the output of '/proc/cpuinfo' for the number of unique
-#   lines with "physical id" in them.
+#   Attempts to use sysfs to get the physical IDs of the processors. Falls
+#   back to /proc/cpuinfo and "physical id" if sysfs is not available.
 #
 # Caveats:
 #
 
-Facter.add("physicalprocessorcount") do
-    confine :kernel => :linux
+Facter.add('physicalprocessorcount') do
+  confine :kernel => :linux
 
-    setcode do
-        ppcount = Facter::Util::Resolution.exec('grep "physical id" /proc/cpuinfo|cut -d: -f 2|sort -u|wc -l')
+  setcode do
+    sysfs_cpu_directory = '/sys/devices/system/cpu' # This should always be there ...
+
+    if File.exists?(sysfs_cpu_directory)
+      #
+      # We assume that the sysfs file system has the correct number of entries
+      # under the "/sys/device/system/cpu" directory and if so then we process
+      # content of the file "physical_package_id" located inside the "topology"
+      # directory in each of the per-CPU sub-directories.
+      #
+      # As per Linux Kernel documentation and the file "cputopology.txt" located
+      # inside the "/usr/src/linux/Documentation" directory we can find following
+      # short explanation:
+      #
+      # (...)
+      #
+      # 1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
+      #
+      #         physical package id of cpuX. Typically corresponds to a physical
+      #         socket number, but the actual value is architecture and platform
+      #         dependent.
+      #
+      # (...)
+      #
+      lookup_pattern = "#{sysfs_cpu_directory}/cpu*/topology/physical_package_id"
+      Dir[lookup_pattern].map { |i| File.read(i).strip }.uniq.size
+    else
+      #
+      # Try to count number of CPUs using the proc file system next ...
+      #
+      # We assume that /proc/cpuinfo has what we need and is so then we need
+      # to make sure that we only count unique entries ...
+      #
+      File.read('/proc/cpuinfo').scan(/physical.+:\s(\d+)/).uniq.size
     end
+  end
 end