Task/affinity fix for Power7 processor with hyper-threading disabled

NEWS

@@ -8,6 +8,8 @@ documents those changes that are of interest to users and admins.
     "rack9blade1" should come before "rack10blade1")
  -- BGQ - Only poll on initialized blocks instead of calling getBlocks on
     each block independently.
+ -- Fix of task/affinity plugin logic for Power7 processors having hyper-
+    threading disabled (cpu mask has gaps).
 
 * Changes in SLURM 2.5.0
 ========================

src/plugins/task/affinity/affinity.c

@@ -271,6 +271,34 @@ int get_cpuset(cpu_set_t *mask, slurmd_job_t *job)
 	return false;
 }
 
+/* Translate global CPU index to local CPU index. This is needed for
+ * Power7 processors with multi-threading disabled. On those processors,
+ * the CPU mask has gaps for the unused threads (different from Intel
+ * processors) which need to be skipped over in the mask used in the
+ * set system call. */
+void reset_cpuset(cpu_set_t *new_mask, cpu_set_t *cur_mask)
+{
+	cpu_set_t newer_mask;
+	int cur_offset, new_offset = 0, last_set = -1;
+
+	CPU_ZERO(&newer_mask);
+	for (cur_offset = 0; cur_offset < CPU_SETSIZE; cur_offset++) {
+		if (!CPU_ISSET(cur_offset, cur_mask))
+			continue;
+		if (CPU_ISSET(new_offset, new_mask)) {
+			CPU_SET(cur_offset, &newer_mask);
+			last_set = cur_offset;
+		}
+		new_offset++;
+	}
+
+	CPU_ZERO(new_mask);
+	for (cur_offset = 0; cur_offset <= last_set; cur_offset++) {
+		if (CPU_ISSET(cur_offset, &newer_mask))
+			CPU_SET(cur_offset, new_mask);
+	}
+}
+
 int slurm_setaffinity(pid_t pid, size_t size, const cpu_set_t *mask)
 {
 	int rval;

src/plugins/task/affinity/affinity.h

@@ -101,6 +101,7 @@
 /*** from affinity.c ***/
 void	slurm_chkaffinity(cpu_set_t *mask, slurmd_job_t *job, int statval);
 int	get_cpuset(cpu_set_t *mask, slurmd_job_t *job);
+void	reset_cpuset(cpu_set_t *new_mask, cpu_set_t *cur_mask);
 int	slurm_setaffinity(pid_t pid, size_t size, const cpu_set_t *mask);
 int	slurm_getaffinity(pid_t pid, size_t size, cpu_set_t *mask);
 

src/plugins/task/affinity/task_affinity.c

@@ -376,9 +376,9 @@ extern int task_pre_launch (slurmd_job_t *job)
 		pid_t mypid  = job->envtp->task_pid;
 
 		slurm_getaffinity(mypid, sizeof(cur_mask), &cur_mask);
-
 		if (get_cpuset(&new_mask, job) &&
 		    (!(job->cpu_bind_type & CPU_BIND_NONE))) {
+			reset_cpuset(&new_mask, &cur_mask);
 			if (conf->task_plugin_param & CPU_BIND_CPUSETS) {
 				rc = slurm_set_cpuset(base, path, mypid,
 						sizeof(new_mask),