libtaskmap: allow unequal tasks per rank in taskmap_check()

Problem: taskmap_check() treats taskmaps as incompatible if nodes have
differing task counts. However, this strict requirement is unnecessary
and blocks valid use cases where tasks may need to be redistributed
across nodes.

Remove the check that tasks per node are equal in the old and new
taskmaps in taskmap_check().

Update an expected failure in the unit tests to an expected success.

Author: grondo

src/common/libtaskmap/taskmap.c

@@ -973,16 +973,6 @@ int taskmap_check (const struct taskmap *old,
                           "got %d total tasks, expected %d",
                           ntasks_new,
                           ntasks_old);
-    for (int i = 0; i < nnodes_old; i++) {
-        ntasks_old = taskmap_ntasks (old, i);
-        ntasks_new = taskmap_ntasks (new, i);
-        if (ntasks_old != ntasks_new)
-            return errprintf (errp,
-                              "node %d has %d tasks, expected %d",
-                              i,
-                              ntasks_new,
-                              ntasks_old);
-    }
     return 0;
 }
 

src/common/libtaskmap/taskmap.h

@@ -90,8 +90,8 @@ int taskmap_nnodes (const struct taskmap *map);
 int taskmap_total_ntasks (const struct taskmap *map);
 
 /*  Check if 'a' and 'b' taskmaps are compatible, i.e. they
- *  have equivalent numbers of total tasks, total nodes, and tasks assigned
- *  to each node.
+ *  have equivalent numbers of total tasks and total nodes.
+ *
  *  Returns 0 on success, -1 with error message in 'errp' on failure.
  */
 int taskmap_check (const struct taskmap *a,

src/common/libtaskmap/test/taskmap.c

@@ -522,12 +522,11 @@ struct check_test check_tests[] = {
     { "[[0,4,4,1]]", "[[0,4,1,4]]", 0, NULL },
     { "[[0,4,4,1]]", "[[0,4,2,2]]", 0, NULL },
     { "[[0,4,4,1]]", "[[0,4,3,1],[0,4,1,1]]", 0, NULL },
+    { "[[0,4,4,1]]", "[[0,2,4,1],[2,1,3,1],[3,1,5,1]]", 0, NULL },
     { "[[0,4,4,1]]", "[[0,4,3,1]]", -1,
       "got 12 total tasks, expected 16" },
     { "[[0,4,4,1]]", "[[0,2,8,1]]", -1,
       "got 2 nodes, expected 4" },
-    { "[[0,4,4,1]]", "[[0,2,4,1],[2,1,3,1],[3,1,5,1]]", -1,
-      "node 2 has 3 tasks, expected 4" },
     { NULL, NULL, 0, NULL },
 };