Re: [RFC PATCH 2/2] sched: Implement adaptative rate limiting of task migrations

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

Hi Mathieu,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on linus/master next-20230906]
[cannot apply to v6.5]
[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/Mathieu-Desnoyers/sched-Rate-limit-migrations-to-1-per-2ms-per-task/20230906-030116
base:   tip/sched/core
patch link:    https://lore.kernel.org/r/20230905171105.1005672-3-mathieu.desnoyers%40efficios.com
patch subject: [RFC PATCH 2/2] sched: Implement adaptative rate limiting of task migrations
config: arm64-randconfig-r023-20230906 (https://download.01.org/0day-ci/archive/20230907/202309070647.wAce8rJl-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230907/202309070647.wAce8rJl-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/202309070647.wAce8rJl-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/sched/fair.c:702:6: warning: no previous prototype for function 'update_entity_lag' [-Wmissing-prototypes]
   void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
        ^
   kernel/sched/fair.c:702:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
   ^
   static 
   kernel/sched/fair.c:6348:6: warning: no previous prototype for function 'init_cfs_bandwidth' [-Wmissing-prototypes]
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
        ^
   kernel/sched/fair.c:6348:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
   ^
   static 
>> kernel/sched/fair.c:7956:8: error: implicit declaration of function 'sched_clock_stable' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                   if (!sched_clock_stable())
                        ^
   kernel/sched/fair.c:7956:8: note: did you mean 'sched_clock_tick'?
   include/linux/sched/clock.h:36:20: note: 'sched_clock_tick' declared here
   static inline void sched_clock_tick(void)
                      ^
   kernel/sched/fair.c:7959:8: error: implicit declaration of function 'sched_clock_stable' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
                   if (!sched_clock_stable())
                        ^
   kernel/sched/fair.c:12831:6: warning: no previous prototype for function 'free_fair_sched_group' [-Wmissing-prototypes]
   void free_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12831:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void free_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:12833:5: warning: no previous prototype for function 'alloc_fair_sched_group' [-Wmissing-prototypes]
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
       ^
   kernel/sched/fair.c:12833:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
   ^
   static 
   kernel/sched/fair.c:12838:6: warning: no previous prototype for function 'online_fair_sched_group' [-Wmissing-prototypes]
   void online_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12838:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void online_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   kernel/sched/fair.c:12840:6: warning: no previous prototype for function 'unregister_fair_sched_group' [-Wmissing-prototypes]
   void unregister_fair_sched_group(struct task_group *tg) { }
        ^
   kernel/sched/fair.c:12840:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void unregister_fair_sched_group(struct task_group *tg) { }
   ^
   static 
   6 warnings and 2 errors generated.


vim +/sched_clock_stable +7956 kernel/sched/fair.c

  7946	
  7947	static void migrate_task_ratelimit_fair(struct task_struct *p, int new_cpu)
  7948	{
  7949		struct sched_entity *se = &p->se;
  7950		u64 now;
  7951	
  7952		/* Rate limit task migration. */
  7953		now = sched_clock_cpu(task_cpu(p));
  7954		if (now < se->next_migration_time) {
  7955			se->nr_migrations_per_window++;
> 7956			if (!sched_clock_stable())
  7957				se->next_migration_time += sched_clock_cpu(new_cpu) - now;
  7958		} else {
  7959			if (!sched_clock_stable())
  7960				now = sched_clock_cpu(new_cpu);
  7961			se->next_migration_time = now + SCHED_MIGRATION_RATELIMIT_WINDOW;
  7962			if (se->nr_migrations_per_window >= se->quota_migrations_per_window)
  7963				se->quota_migrations_per_window = max(1, se->quota_migrations_per_window >> 1);
  7964			else
  7965				se->quota_migrations_per_window =
  7966					min(SCHED_MIGRATION_QUOTA,
  7967					    se->quota_migrations_per_window + SCHED_MIGRATION_QUOTA_REPLENISH);
  7968			se->nr_migrations_per_window = 1;
  7969		}
  7970	}
  7971	

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