Commit 328fefad authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull scheduler fixes from Ingo Molnar:
 "Two fixes: a guest-cputime accounting fix, and a cgroup bandwidth
  quota precision fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/vtime: Fix guest/system mis-accounting on task switch
  sched/fair: Scale bandwidth quota and period without losing quota/period ratio precision
parents 465a7e29 68e7a4d6

kernel/sched/cputime.c

+3 −3
Original line number Diff line number Diff line
@@ -740,7 +740,7 @@ void vtime_account_system(struct task_struct *tsk) 


	write_seqcount_begin(&vtime->seqcount);

	/* We might have scheduled out from guest path */

	if (current->flags & PF_VCPU)

	if (tsk->flags & PF_VCPU)

		vtime_account_guest(tsk, vtime);

	else

		__vtime_account_system(tsk, vtime);
@@ -783,7 +783,7 @@ void vtime_guest_enter(struct task_struct *tsk) 
	 */

	write_seqcount_begin(&vtime->seqcount);

	__vtime_account_system(tsk, vtime);

	current->flags |= PF_VCPU;

	tsk->flags |= PF_VCPU;

	write_seqcount_end(&vtime->seqcount);

}

EXPORT_SYMBOL_GPL(vtime_guest_enter);
@@ -794,7 +794,7 @@ void vtime_guest_exit(struct task_struct *tsk) 


	write_seqcount_begin(&vtime->seqcount);

	vtime_account_guest(tsk, vtime);

	current->flags &= ~PF_VCPU;

	tsk->flags &= ~PF_VCPU;

	write_seqcount_end(&vtime->seqcount);

}

EXPORT_SYMBOL_GPL(vtime_guest_exit);

kernel/sched/fair.c

+22 −14
Original line number Diff line number Diff line
@@ -4926,20 +4926,28 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) 
		if (++count > 3) {

			u64 new, old = ktime_to_ns(cfs_b->period);



			new = (old * 147) / 128; /* ~115% */

			new = min(new, max_cfs_quota_period);



			/*

			 * Grow period by a factor of 2 to avoid losing precision.

			 * Precision loss in the quota/period ratio can cause __cfs_schedulable

			 * to fail.

			 */

			new = old * 2;

			if (new < max_cfs_quota_period) {

				cfs_b->period = ns_to_ktime(new);



			/* since max is 1s, this is limited to 1e9^2, which fits in u64 */

			cfs_b->quota *= new;

			cfs_b->quota = div64_u64(cfs_b->quota, old);

				cfs_b->quota *= 2;



				pr_warn_ratelimited(

	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us %lld, cfs_quota_us = %lld)\n",

	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",

					smp_processor_id(),

					div_u64(new, NSEC_PER_USEC),

					div_u64(cfs_b->quota, NSEC_PER_USEC));

			} else {

				pr_warn_ratelimited(

	"cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",

					smp_processor_id(),

					div_u64(old, NSEC_PER_USEC),

					div_u64(cfs_b->quota, NSEC_PER_USEC));

			}



			/* reset count so we don't come right back in here */

			count = 0;

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