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Date: Fri, 5 Aug 2022 10:11:33 +0800
From: Chengming Zhou <zhouchengming@...edance.com>
To: kernel test robot <lkp@...el.com>
Cc: kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org,
mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
vschneid@...hat.com
Subject: Re: [PATCH v3 08/10] sched/fair: refactor detach/attach_entity_cfs_rq
using update_load_avg()
On 2022/8/1 16:07, 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 next-20220728]
> [cannot apply to linus/master v5.19]
> [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/Chengming-Zhou/sched-fair-task-load-tracking-optimization-and-cleanup/20220801-122957
> base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 8da3d9b8590bc178752d4b72938745e9a6c4c416
> config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220801/202208011647.2KU7IF9Y-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
> reproduce (this is a W=1 build):
> # https://github.com/intel-lab-lkp/linux/commit/336247ff1d2b402a18689fd891d79e99d8b444fc
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Chengming-Zhou/sched-fair-task-load-tracking-optimization-and-cleanup/20220801-122957
> git checkout 336247ff1d2b402a18689fd891d79e99d8b444fc
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@...el.com>
>
> All errors (new ones prefixed by >>):
>
> kernel/sched/fair.c:672:5: warning: no previous prototype for 'sched_update_scaling' [-Wmissing-prototypes]
> 672 | int sched_update_scaling(void)
> | ^~~~~~~~~~~~~~~~~~~~
> kernel/sched/fair.c: In function 'enqueue_entity':
>>> kernel/sched/fair.c:4462:16: error: 'struct sched_entity' has no member named 'avg'
> 4462 | if (!se->avg.last_update_time)
> | ^~
>
Thanks for the test report!
It seems because sched_entity has no member avg on !CONFIG_SMP,
I think we'd better drop this patch for now since it's just code
refactor, not real improvement.
>
> vim +4462 kernel/sched/fair.c
>
> 4419
> 4420 /*
> 4421 * MIGRATION
> 4422 *
> 4423 * dequeue
> 4424 * update_curr()
> 4425 * update_min_vruntime()
> 4426 * vruntime -= min_vruntime
> 4427 *
> 4428 * enqueue
> 4429 * update_curr()
> 4430 * update_min_vruntime()
> 4431 * vruntime += min_vruntime
> 4432 *
> 4433 * this way the vruntime transition between RQs is done when both
> 4434 * min_vruntime are up-to-date.
> 4435 *
> 4436 * WAKEUP (remote)
> 4437 *
> 4438 * ->migrate_task_rq_fair() (p->state == TASK_WAKING)
> 4439 * vruntime -= min_vruntime
> 4440 *
> 4441 * enqueue
> 4442 * update_curr()
> 4443 * update_min_vruntime()
> 4444 * vruntime += min_vruntime
> 4445 *
> 4446 * this way we don't have the most up-to-date min_vruntime on the originating
> 4447 * CPU and an up-to-date min_vruntime on the destination CPU.
> 4448 */
> 4449
> 4450 static void
> 4451 enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> 4452 {
> 4453 bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED);
> 4454 bool curr = cfs_rq->curr == se;
> 4455 int action = UPDATE_TG;
> 4456
> 4457 /*
> 4458 * !last_update_time means we've passed through migrate_task_rq_fair()
> 4459 * or task_change_group_fair() indicating we migrated cfs_rq. IOW we're
> 4460 * enqueueing a task on a new CPU or moving task to a new cgroup.
> 4461 */
>> 4462 if (!se->avg.last_update_time)
> 4463 action |= DO_ATTACH;
> 4464
> 4465 /*
> 4466 * If we're the current task, we must renormalise before calling
> 4467 * update_curr().
> 4468 */
> 4469 if (renorm && curr)
> 4470 se->vruntime += cfs_rq->min_vruntime;
> 4471
> 4472 update_curr(cfs_rq);
> 4473
> 4474 /*
> 4475 * Otherwise, renormalise after, such that we're placed at the current
> 4476 * moment in time, instead of some random moment in the past. Being
> 4477 * placed in the past could significantly boost this task to the
> 4478 * fairness detriment of existing tasks.
> 4479 */
> 4480 if (renorm && !curr)
> 4481 se->vruntime += cfs_rq->min_vruntime;
> 4482
> 4483 /*
> 4484 * When enqueuing a sched_entity, we must:
> 4485 * - Update loads to have both entity and cfs_rq synced with now.
> 4486 * - For group_entity, update its runnable_weight to reflect the new
> 4487 * h_nr_running of its group cfs_rq.
> 4488 * - For group_entity, update its weight to reflect the new share of
> 4489 * its group cfs_rq
> 4490 * - Add its new weight to cfs_rq->load.weight
> 4491 */
> 4492 update_load_avg(cfs_rq, se, action);
> 4493 se_update_runnable(se);
> 4494 update_cfs_group(se);
> 4495 account_entity_enqueue(cfs_rq, se);
> 4496
> 4497 if (flags & ENQUEUE_WAKEUP)
> 4498 place_entity(cfs_rq, se, 0);
> 4499
> 4500 check_schedstat_required();
> 4501 update_stats_enqueue_fair(cfs_rq, se, flags);
> 4502 check_spread(cfs_rq, se);
> 4503 if (!curr)
> 4504 __enqueue_entity(cfs_rq, se);
> 4505 se->on_rq = 1;
> 4506
> 4507 if (cfs_rq->nr_running == 1) {
> 4508 check_enqueue_throttle(cfs_rq);
> 4509 if (!throttled_hierarchy(cfs_rq))
> 4510 list_add_leaf_cfs_rq(cfs_rq);
> 4511 }
> 4512 }
> 4513
>
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