Re: [PATCH 3/3] sched/fair: Test that the average lag across the system is zero

[kernel test robot <lkp@intel.com>]

Hi Dhaval,

kernel test robot noticed the following build errors:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on linus/master v6.15-rc5 next-20250507]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Dhaval-Giani-AMD/sched-fair-Add-a-test-to-test-that-a-task-selected-to-run-has-positive-lag/20250423-081648
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20250422-b4-eevdf-tests-v1-post-v1-3-5b174f040f55%40gianis.ca
patch subject: [PATCH 3/3] sched/fair: Test that the average lag across the system is zero
config: i386-randconfig-001-20250426 (https://download.01.org/0day-ci/archive/20250508/202505081552.vqYbpmQi-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250508/202505081552.vqYbpmQi-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505081552.vqYbpmQi-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: kernel/sched/eevdf-tests.o: in function `test_eevdf_cfs_rq_zero_lag':
>> kernel/sched/eevdf-tests.c:150: undefined reference to `__udivdi3'


vim +150 kernel/sched/eevdf-tests.c

    98	
    99	/*
   100	 * we do, what we need to do
   101	 */
   102	#define __node_2_se(node) \
   103		rb_entry((node), struct sched_entity, run_node)
   104	
   105	static bool test_eevdf_cfs_rq_zero_lag(struct cfs_rq *cfs, struct list_head *tg_se)
   106	{
   107		u64 cfs_avg_vruntime;
   108		u64 calculated_avg_vruntime;
   109	
   110		u64 total_vruntime = 0;
   111		u64 nr_tasks = 0;
   112	
   113		struct sched_entity *se;
   114		struct rb_node *node;
   115		struct rb_root *root;
   116	
   117		cfs_avg_vruntime = avg_vruntime(cfs);
   118	
   119		/*
   120		 * Walk through the rb tree -> look at the se->vruntime value and add it
   121		 */
   122	
   123		total_vruntime = 0;
   124		nr_tasks = 0;
   125	
   126		root = &cfs->tasks_timeline.rb_root;
   127	
   128		for (node = rb_first(root); node; node = rb_next(node)) {
   129			se = __node_2_se(node);
   130			WARN_ON_ONCE(__builtin_add_overflow(total_vruntime,
   131						se->vruntime, &total_vruntime));
   132			/*
   133			 * if it is a task group, add to a list to look at later
   134			 */
   135			if (!entity_is_task(se))
   136				list_add_tail(&se->tg_entry, tg_se);
   137			nr_tasks++;
   138		}
   139	
   140		if (cfs->curr) {
   141			WARN_ON_ONCE(__builtin_add_overflow(total_vruntime,
   142						cfs->curr->vruntime, &total_vruntime));
   143			nr_tasks++;
   144		}
   145	
   146		/* If there are no tasks, there is no lag :-) */
   147		if (!nr_tasks)
   148			return true;
   149	
 > 150		calculated_avg_vruntime = total_vruntime / nr_tasks;
   151	
   152		return (calculated_avg_vruntime == cfs_avg_vruntime);
   153	

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