qemu: Support numad

numad is an user-level daemon that monitors NUMA topology and
processes resource consumption to facilitate good NUMA resource
alignment of applications/virtual machines to improve performance
and minimize cost of remote memory latencies. It provides a
pre-placement advisory interface, so significant processes can
be pre-bound to nodes with sufficient available resources.

More details: http://fedoraproject.org/wiki/Features/numad

"numad -w ncpus:memory_amount" is the advisory interface numad
provides currently.

This patch add the support by introducing a new XML attribute
for <vcpu>. e.g.

  <vcpu placement="auto">4</vcpu>
  <vcpu placement="static" cpuset="1-10^6">4</vcpu>

The returned advisory nodeset from numad will be printed
in domain's dumped XML. e.g.
  <vcpu placement="auto" cpuset="1-10^6">4</vcpu>

If placement is "auto", the number of vcpus and the current
memory amount specified in domain XML will be used for numad
command line (numad uses MB for memory amount):
  numad -w $num_of_vcpus:$current_memory_amount / 1024

The advisory nodeset returned from numad will be used to set
domain process CPU affinity then. (e.g. qemuProcessInitCpuAffinity).

If the user specifies both CPU affinity policy (e.g.
(<vcpu cpuset="1-10,^7,^8">4</vcpu>) and placement == "auto"
the specified CPU affinity will be overridden.

Only QEMU/KVM drivers support it now.

See docs update in patch for more details.

configure.ac

@@ -1445,6 +1445,14 @@ AM_CONDITIONAL([HAVE_NUMACTL], [test "$with_numactl" != "no"])
 AC_SUBST([NUMACTL_CFLAGS])
 AC_SUBST([NUMACTL_LIBS])
 
+dnl Do we have numad?
+if test "$with_qemu" = "yes"; then
+    AC_PATH_PROG([NUMAD], [numad], [], [/bin:/usr/bin:/usr/local/bin:$PATH])
+
+    if test -n "$NUMAD"; then
+        AC_DEFINE_UNQUOTED([NUMAD],["$NUMAD"], [Location or name of the numad program])
+    fi
+fi
 
 dnl pcap lib
 LIBPCAP_CONFIG="pcap-config"