Re: [PATCH 2/4] sched/fair: Make CFS bandwidth controller burstable

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

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Hi Huaixin,

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 v5.10 next-20201217]
[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/0day-ci/linux/commits/Huaixin-Chang/sched-fair-Burstable-CFS-bandwidth-controller/20201217-155214
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 5b78f2dc315354c05300795064f587366a02c6ff
config: i386-randconfig-r013-20200812 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/d2f5cde464c872307ee33f78ba167a6f3334697c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Huaixin-Chang/sched-fair-Burstable-CFS-bandwidth-controller/20201217-155214
        git checkout d2f5cde464c872307ee33f78ba167a6f3334697c
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   ld: kernel/sched/core.o: in function `tg_set_cfs_bandwidth':
>> kernel/sched/core.c:8596: undefined reference to `__udivdi3'


vim +8596 kernel/sched/core.c

  8521	
  8522	static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota,
  8523								u64 burst)
  8524	{
  8525		int i, ret = 0, runtime_enabled, runtime_was_enabled;
  8526		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
  8527		u64 buffer, burst_onset;
  8528	
  8529		if (tg == &root_task_group)
  8530			return -EINVAL;
  8531	
  8532		/*
  8533		 * Ensure we have at some amount of bandwidth every period.  This is
  8534		 * to prevent reaching a state of large arrears when throttled via
  8535		 * entity_tick() resulting in prolonged exit starvation.
  8536		 */
  8537		if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
  8538			return -EINVAL;
  8539	
  8540		/*
  8541		 * Likewise, bound things on the otherside by preventing insane quota
  8542		 * periods.  This also allows us to normalize in computing quota
  8543		 * feasibility.
  8544		 */
  8545		if (period > max_cfs_quota_period)
  8546			return -EINVAL;
  8547	
  8548		/*
  8549		 * Bound quota to defend quota against overflow during bandwidth shift.
  8550		 */
  8551		if (quota != RUNTIME_INF && quota > max_cfs_runtime)
  8552			return -EINVAL;
  8553	
  8554		/*
  8555		 * Bound burst to defend burst against overflow during bandwidth shift.
  8556		 */
  8557		if (burst > max_cfs_runtime)
  8558			return -EINVAL;
  8559	
  8560		if (quota == RUNTIME_INF)
  8561			buffer = RUNTIME_INF;
  8562		else
  8563			buffer = min(max_cfs_runtime, quota + burst);
  8564		/*
  8565		 * Prevent race between setting of cfs_rq->runtime_enabled and
  8566		 * unthrottle_offline_cfs_rqs().
  8567		 */
  8568		get_online_cpus();
  8569		mutex_lock(&cfs_constraints_mutex);
  8570		ret = __cfs_schedulable(tg, period, quota);
  8571		if (ret)
  8572			goto out_unlock;
  8573	
  8574		runtime_enabled = quota != RUNTIME_INF;
  8575		runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
  8576		/*
  8577		 * If we need to toggle cfs_bandwidth_used, off->on must occur
  8578		 * before making related changes, and on->off must occur afterwards
  8579		 */
  8580		if (runtime_enabled && !runtime_was_enabled)
  8581			cfs_bandwidth_usage_inc();
  8582		raw_spin_lock_irq(&cfs_b->lock);
  8583		cfs_b->period = ns_to_ktime(period);
  8584		cfs_b->quota = quota;
  8585		cfs_b->burst = burst;
  8586		cfs_b->buffer = buffer;
  8587	
  8588		cfs_b->max_overrun = DIV_ROUND_UP_ULL(max_cfs_runtime, quota);
  8589		cfs_b->runtime = cfs_b->quota;
  8590	
  8591		/* burst_onset needed */
  8592		if (cfs_b->quota != RUNTIME_INF &&
  8593				sysctl_sched_cfs_bw_burst_enabled &&
  8594				sysctl_sched_cfs_bw_burst_onset_percent > 0) {
  8595	
> 8596			burst_onset = burst / 100 *
  8597				sysctl_sched_cfs_bw_burst_onset_percent;
  8598	
  8599			cfs_b->runtime += burst_onset;
  8600			cfs_b->runtime = min(max_cfs_runtime, cfs_b->runtime);
  8601		}
  8602	
  8603		/* Restart the period timer (if active) to handle new period expiry: */
  8604		if (runtime_enabled)
  8605			start_cfs_bandwidth(cfs_b, 1);
  8606	
  8607		raw_spin_unlock_irq(&cfs_b->lock);
  8608	
  8609		for_each_online_cpu(i) {
  8610			struct cfs_rq *cfs_rq = tg->cfs_rq[i];
  8611			struct rq *rq = cfs_rq->rq;
  8612			struct rq_flags rf;
  8613	
  8614			rq_lock_irq(rq, &rf);
  8615			cfs_rq->runtime_enabled = runtime_enabled;
  8616			cfs_rq->runtime_remaining = 0;
  8617	
  8618			if (cfs_rq->throttled)
  8619				unthrottle_cfs_rq(cfs_rq);
  8620			rq_unlock_irq(rq, &rf);
  8621		}
  8622		if (runtime_was_enabled && !runtime_enabled)
  8623			cfs_bandwidth_usage_dec();
  8624	out_unlock:
  8625		mutex_unlock(&cfs_constraints_mutex);
  8626		put_online_cpus();
  8627	
  8628		return ret;
  8629	}
  8630	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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