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Commit 0b79dada authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of... 

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes:
  sched: fix share (re)distribution
  softlockup: fix NOHZ wakeup
  seqlock: livelock fix
parents 50be4917 3f5087a2

include/linux/seqlock.h

+29 −17
Original line number Diff line number Diff line
@@ -85,23 +85,29 @@ static inline int write_tryseqlock(seqlock_t *sl) 
/* Start of read calculation -- fetch last complete writer token */

static __always_inline unsigned read_seqbegin(const seqlock_t *sl)

{

	unsigned ret = sl->sequence;

	unsigned ret;



repeat:

	ret = sl->sequence;

	smp_rmb();

	if (unlikely(ret & 1)) {

		cpu_relax();

		goto repeat;

	}



	return ret;

}



/* Test if reader processed invalid data.

 * If initial values is odd, 

 *	then writer had already started when section was entered

 * If sequence value changed

 *	then writer changed data while in section

/*

 * Test if reader processed invalid data.

 *

 * Using xor saves one conditional branch.

 * If sequence value changed then writer changed data while in section.

 */

static __always_inline int read_seqretry(const seqlock_t *sl, unsigned iv)

static __always_inline int read_seqretry(const seqlock_t *sl, unsigned start)

{

	smp_rmb();

	return (iv & 1) | (sl->sequence ^ iv);



	return (sl->sequence != start);

}
@@ -122,20 +128,26 @@ typedef struct seqcount { 
/* Start of read using pointer to a sequence counter only.  */

static inline unsigned read_seqcount_begin(const seqcount_t *s)

{

	unsigned ret = s->sequence;

	unsigned ret;



repeat:

	ret = s->sequence;

	smp_rmb();

	if (unlikely(ret & 1)) {

		cpu_relax();

		goto repeat;

	}

	return ret;

}



/* Test if reader processed invalid data.

 * Equivalent to: iv is odd or sequence number has changed.

 *                (iv & 1) || (*s != iv)

 * Using xor saves one conditional branch.

/*

 * Test if reader processed invalid data because sequence number has changed.

 */

static inline int read_seqcount_retry(const seqcount_t *s, unsigned iv)

static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)

{

	smp_rmb();

	return (iv & 1) | (s->sequence ^ iv);



	return s->sequence != start;

}

kernel/sched.c

+2 −45
Original line number Diff line number Diff line
@@ -1656,42 +1656,6 @@ void aggregate_group_weight(struct task_group *tg, struct sched_domain *sd) 
	aggregate(tg, sd)->task_weight = task_weight;

}



/*

 * Redistribute tg->shares amongst all tg->cfs_rq[]s.

 */

static void __aggregate_redistribute_shares(struct task_group *tg)

{

	int i, max_cpu = smp_processor_id();

	unsigned long rq_weight = 0;

	unsigned long shares, max_shares = 0, shares_rem = tg->shares;



	for_each_possible_cpu(i)

		rq_weight += tg->cfs_rq[i]->load.weight;



	for_each_possible_cpu(i) {

		/*

		 * divide shares proportional to the rq_weights.

		 */

		shares = tg->shares * tg->cfs_rq[i]->load.weight;

		shares /= rq_weight + 1;



		tg->cfs_rq[i]->shares = shares;



		if (shares > max_shares) {

			max_shares = shares;

			max_cpu = i;

		}

		shares_rem -= shares;

	}



	/*

	 * Ensure it all adds up to tg->shares; we can loose a few

	 * due to rounding down when computing the per-cpu shares.

	 */

	if (shares_rem)

		tg->cfs_rq[max_cpu]->shares += shares_rem;

}



/*

 * Compute the weight of this group on the given cpus.

 */
@@ -1701,18 +1665,11 @@ void aggregate_group_shares(struct task_group *tg, struct sched_domain *sd) 
	unsigned long shares = 0;

	int i;



again:

	for_each_cpu_mask(i, sd->span)

		shares += tg->cfs_rq[i]->shares;



	/*

	 * When the span doesn't have any shares assigned, but does have

	 * tasks to run do a machine wide rebalance (should be rare).

	 */

	if (unlikely(!shares && aggregate(tg, sd)->rq_weight)) {

		__aggregate_redistribute_shares(tg);

		goto again;

	}

	if ((!shares && aggregate(tg, sd)->rq_weight) || shares > tg->shares)

		shares = tg->shares;



	aggregate(tg, sd)->shares = shares;

}

kernel/time/tick-sched.c

+1 −0
Original line number Diff line number Diff line
@@ -393,6 +393,7 @@ void tick_nohz_restart_sched_tick(void) 
		sub_preempt_count(HARDIRQ_OFFSET);

	}



	touch_softlockup_watchdog();

	/*

	 * Cancel the scheduled timer and restore the tick

	 */