task_psi_group
if (prev && task_psi_group(prev) == task_psi_group(curr))
for_each_group(group, task_psi_group(curr)) {
for_each_group(group, task_psi_group(task))
for_each_group(group, task_psi_group(next)) {
for_each_group(group, task_psi_group(prev)) {