[PATCH 2 of 3] libxl, xl: user can ask for min and max nodes to use during placement

[Dario Faggioli <dario.faggioli@citrix.com>]

And the placement algorithm will stick to that, or fail. This happens
adding support for "minnodes=" and "maxnodes=" in the domain config
file parser.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -133,6 +133,18 @@ the same time, achieving efficient utili
 
 =back
 
+=item B<minnodes=N>
+
+Tells libxl to place the new domain on at least `N` nodes. This is only
+effective if automatic NUMA placement occurs (i.e., if no `cpus=` option
+is specified).
+
+=item B<maxnodes=M>
+
+Tells libxl to place the new domain on at most `M` nodes. This is only
+effective if automatic NUMA placement occurs (i.e., if no `cpus=` option
+is specified).
+
 =head3 CPU Scheduling
 
 =over 4
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -219,6 +219,11 @@ int libxl__domain_build_info_setdefault(
 
     libxl_defbool_setdefault(&b_info->numa_placement, true);
 
+    if (!b_info->min_nodes)
+        b_info->min_nodes = 0;
+    if (!b_info->max_nodes)
+        b_info->max_nodes = 0;
+
     if (b_info->max_memkb == LIBXL_MEMKB_DEFAULT)
         b_info->max_memkb = 32 * 1024;
     if (b_info->target_memkb == LIBXL_MEMKB_DEFAULT)
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -174,7 +174,8 @@ static int numa_place_domain(libxl__gc *
     /* Find the best candidate with enough free memory and at least
      * as much pcpus as the domain has vcpus.  */
     rc = libxl__get_numa_candidate(gc, memkb, info->max_vcpus,
-                                   0, 0, &cpupool_info.cpumap,
+                                   info->min_nodes, info->max_nodes,
+                                   &cpupool_info.cpumap,
                                    numa_cmpf, &candidate, &found);
     if (rc)
         goto out;
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -262,6 +262,8 @@ libxl_domain_build_info = Struct("domain
     ("avail_vcpus",     libxl_bitmap),
     ("cpumap",          libxl_bitmap),
     ("numa_placement",  libxl_defbool),
+    ("min_nodes",       integer),
+    ("max_nodes",       integer),
     ("tsc_mode",        libxl_tsc_mode),
     ("max_memkb",       MemKB),
     ("target_memkb",    MemKB),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -731,6 +731,11 @@ static void parse_config_data(const char
         libxl_defbool_set(&b_info->numa_placement, false);
     }
 
+    if (!xlu_cfg_get_long (config, "minnodes", &l, 0))
+        b_info->min_nodes = l;
+    if (!xlu_cfg_get_long (config, "maxnodes", &l, 0))
+        b_info->max_nodes = l;
+
     if (!xlu_cfg_get_long (config, "memory", &l, 0)) {
         b_info->max_memkb = l * 1024;
         b_info->target_memkb = b_info->max_memkb;