Re: [RFC] sched/fair: Mitigate the impact of retrieving tg->load_avg

Re: [RFC] sched/fair: Mitigate the impact of retrieving tg->load_avg

[kernel test robot]

Hi Vinicius,

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

[auto build test ERROR on v6.16-rc6]
[also build test ERROR on linus/master]
[cannot apply to tip/sched/core next-20250714]
[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/Vinicius-Costa-Gomes/sched-fair-Mitigate-the-impact-of-retrieving-tg-load_avg/20250715-073036
base:   v6.16-rc6
patch link:    https://lore.kernel.org/r/20250714232915.523679-1-vinicius.gomes%40intel.com
patch subject: [RFC] sched/fair: Mitigate the impact of retrieving tg->load_avg
config: loongarch-randconfig-001-20250715 (https://download.01.org/0day-ci/archive/20250715/202507150900.nqPPaczK-lkp@intel.com/config)
compiler: clang version 21.0.0git (https://github.com/llvm/llvm-project 16534d19bf50bde879a83f0ae62875e2c5120e64)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250715/202507150900.nqPPaczK-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/202507150900.nqPPaczK-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/sched/fair.c:4000:21: error: no member named 'last_update_tg_load_avg' in 'struct cfs_rq'
    4000 |         if (now - gcfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
         |                   ~~~~~~~  ^
   1 error generated.


vim +4000 kernel/sched/fair.c

  3974	
  3975	/*
  3976	 * Recomputes the group entity based on the current state of its group
  3977	 * runqueue.
  3978	 */
  3979	static void update_cfs_group(struct sched_entity *se)
  3980	{
  3981		struct cfs_rq *gcfs_rq = group_cfs_rq(se);
  3982		long shares;
  3983		u64 now;
  3984	
  3985		/*
  3986		 * When a group becomes empty, preserve its weight. This matters for
  3987		 * DELAY_DEQUEUE.
  3988		 */
  3989		if (!gcfs_rq || !gcfs_rq->load.weight)
  3990			return;
  3991	
  3992		if (throttled_hierarchy(gcfs_rq))
  3993			return;
  3994	
  3995		/*
  3996		 * For migration heavy workloads, access to tg->load_avg can be
  3997		 * unbound. Limit the update rate to at most once per ms.
  3998		 */
  3999		now = sched_clock_cpu(cpu_of(rq_of(gcfs_rq)));
> 4000		if (now - gcfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
  4001			return;
  4002	

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