Re: [External] Re: [PATCH v2 2/2] sched/fair: optimize and simplify rq leaf_cfs_rq_list

[Chengming Zhou <zhouchengming@bytedance.com>]

On 2022/5/26 16:53, kernel test robot wrote:
> Hi Chengming,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on tip/sched/core]
> [also build test ERROR on tip/master linus/master v5.18 next-20220525]
> [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]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Chengming-Zhou/sched-fair-optimize-and-simplify-rq-leaf_cfs_rq_list/20220526-151850
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 991d8d8142cad94f9c5c05db25e67fa83d6f772a
> config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20220526/202205261617.YUT1ixQ8-lkp@intel.com/config)
> compiler: powerpc-linux-gcc (GCC) 11.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/intel-lab-lkp/linux/commit/cb2b1810aeb3f8f290a932f3e625ab9df1110054
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Chengming-Zhou/sched-fair-optimize-and-simplify-rq-leaf_cfs_rq_list/20220526-151850
>         git checkout cb2b1810aeb3f8f290a932f3e625ab9df1110054
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash kernel/sched/
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>

Thanks, will fix !CONFIG_FAIR_GROUP_SCHED build next version.

> 
> All errors (new ones prefixed by >>):
> 
>    kernel/sched/fair.c:645:5: warning: no previous prototype for 'sched_update_scaling' [-Wmissing-prototypes]
>      645 | int sched_update_scaling(void)
>          |     ^~~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c: In function 'enqueue_entity':
>>> kernel/sched/fair.c:4343:22: error: implicit declaration of function 'throttled_hierarchy' [-Werror=implicit-function-declaration]
>     4343 |                 if (!throttled_hierarchy(cfs_rq))
>          |                      ^~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c: At top level:
>>> kernel/sched/fair.c:5484:19: error: static declaration of 'throttled_hierarchy' follows non-static declaration
>     5484 | static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
>          |                   ^~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:4343:22: note: previous implicit declaration of 'throttled_hierarchy' with type 'int()'
>     4343 |                 if (!throttled_hierarchy(cfs_rq))
>          |                      ^~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:5495:6: warning: no previous prototype for 'init_cfs_bandwidth' [-Wmissing-prototypes]
>     5495 | void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
>          |      ^~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:11654:6: warning: no previous prototype for 'free_fair_sched_group' [-Wmissing-prototypes]
>    11654 | void free_fair_sched_group(struct task_group *tg) { }
>          |      ^~~~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:11656:5: warning: no previous prototype for 'alloc_fair_sched_group' [-Wmissing-prototypes]
>    11656 | int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
>          |     ^~~~~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:11661:6: warning: no previous prototype for 'online_fair_sched_group' [-Wmissing-prototypes]
>    11661 | void online_fair_sched_group(struct task_group *tg) { }
>          |      ^~~~~~~~~~~~~~~~~~~~~~~
>    kernel/sched/fair.c:11663:6: warning: no previous prototype for 'unregister_fair_sched_group' [-Wmissing-prototypes]
>    11663 | void unregister_fair_sched_group(struct task_group *tg) { }
>          |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>    cc1: some warnings being treated as errors
> 
> 
> vim +/throttled_hierarchy +4343 kernel/sched/fair.c
> 
>   4263	
>   4264	/*
>   4265	 * MIGRATION
>   4266	 *
>   4267	 *	dequeue
>   4268	 *	  update_curr()
>   4269	 *	    update_min_vruntime()
>   4270	 *	  vruntime -= min_vruntime
>   4271	 *
>   4272	 *	enqueue
>   4273	 *	  update_curr()
>   4274	 *	    update_min_vruntime()
>   4275	 *	  vruntime += min_vruntime
>   4276	 *
>   4277	 * this way the vruntime transition between RQs is done when both
>   4278	 * min_vruntime are up-to-date.
>   4279	 *
>   4280	 * WAKEUP (remote)
>   4281	 *
>   4282	 *	->migrate_task_rq_fair() (p->state == TASK_WAKING)
>   4283	 *	  vruntime -= min_vruntime
>   4284	 *
>   4285	 *	enqueue
>   4286	 *	  update_curr()
>   4287	 *	    update_min_vruntime()
>   4288	 *	  vruntime += min_vruntime
>   4289	 *
>   4290	 * this way we don't have the most up-to-date min_vruntime on the originating
>   4291	 * CPU and an up-to-date min_vruntime on the destination CPU.
>   4292	 */
>   4293	
>   4294	static void
>   4295	enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
>   4296	{
>   4297		bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED);
>   4298		bool curr = cfs_rq->curr == se;
>   4299	
>   4300		/*
>   4301		 * If we're the current task, we must renormalise before calling
>   4302		 * update_curr().
>   4303		 */
>   4304		if (renorm && curr)
>   4305			se->vruntime += cfs_rq->min_vruntime;
>   4306	
>   4307		update_curr(cfs_rq);
>   4308	
>   4309		/*
>   4310		 * Otherwise, renormalise after, such that we're placed at the current
>   4311		 * moment in time, instead of some random moment in the past. Being
>   4312		 * placed in the past could significantly boost this task to the
>   4313		 * fairness detriment of existing tasks.
>   4314		 */
>   4315		if (renorm && !curr)
>   4316			se->vruntime += cfs_rq->min_vruntime;
>   4317	
>   4318		/*
>   4319		 * When enqueuing a sched_entity, we must:
>   4320		 *   - Update loads to have both entity and cfs_rq synced with now.
>   4321		 *   - Add its load to cfs_rq->runnable_avg
>   4322		 *   - For group_entity, update its weight to reflect the new share of
>   4323		 *     its group cfs_rq
>   4324		 *   - Add its new weight to cfs_rq->load.weight
>   4325		 */
>   4326		update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
>   4327		se_update_runnable(se);
>   4328		update_cfs_group(se);
>   4329		account_entity_enqueue(cfs_rq, se);
>   4330	
>   4331		if (flags & ENQUEUE_WAKEUP)
>   4332			place_entity(cfs_rq, se, 0);
>   4333	
>   4334		check_schedstat_required();
>   4335		update_stats_enqueue_fair(cfs_rq, se, flags);
>   4336		check_spread(cfs_rq, se);
>   4337		if (!curr)
>   4338			__enqueue_entity(cfs_rq, se);
>   4339		se->on_rq = 1;
>   4340	
>   4341		if (cfs_rq->nr_running == 1) {
>   4342			check_enqueue_throttle(cfs_rq);
>> 4343			if (!throttled_hierarchy(cfs_rq))
>   4344				list_add_leaf_cfs_rq(cfs_rq);
>   4345		}
>   4346	}
>   4347	
>