[linux-2.6-block.git] / kernel / sched_features.h

/*
 * Only give sleepers 50% of their service deficit. This allows
 * them to run sooner, but does not allow tons of sleepers to
 * rip the spread apart.
 */
SCHED_FEAT(GENTLE_FAIR_SLEEPERS, 1)

/*
 * Place new tasks ahead so that they do not starve already running
 * tasks
 */
SCHED_FEAT(START_DEBIT, 1)

/*
 * Based on load and program behaviour, see if it makes sense to place
 * a newly woken task on the same cpu as the task that woke it --
 * improve cache locality. Typically used with SYNC wakeups as
 * generated by pipes and the like, see also SYNC_WAKEUPS.
 */
SCHED_FEAT(AFFINE_WAKEUPS, 1)

/*
 * Prefer to schedule the task we woke last (assuming it failed
 * wakeup-preemption), since its likely going to consume data we
 * touched, increases cache locality.
 */
SCHED_FEAT(NEXT_BUDDY, 0)

/*
 * Prefer to schedule the task that ran last (when we did
 * wake-preempt) as that likely will touch the same data, increases
 * cache locality.
 */
SCHED_FEAT(LAST_BUDDY, 1)

/*
 * Consider buddies to be cache hot, decreases the likelyness of a
 * cache buddy being migrated away, increases cache locality.
 */
SCHED_FEAT(CACHE_HOT_BUDDY, 1)

/*
 * Use arch dependent cpu power functions
 */
SCHED_FEAT(ARCH_POWER, 0)

SCHED_FEAT(HRTICK, 0)
SCHED_FEAT(DOUBLE_TICK, 0)
SCHED_FEAT(LB_BIAS, 1)

/*
 * Spin-wait on mutex acquisition when the mutex owner is running on
 * another cpu -- assumes that when the owner is running, it will soon
 * release the lock. Decreases scheduling overhead.
 */
SCHED_FEAT(OWNER_SPIN, 1)

/*
 * Decrement CPU power based on time not spent running tasks
 */
SCHED_FEAT(NONTASK_POWER, 1)

/*
 * Queue remote wakeups on the target CPU and process them
 * using the scheduler IPI. Reduces rq->lock contention/bounces.
 */
SCHED_FEAT(TTWU_QUEUE, 1)

SCHED_FEAT(FORCE_SD_OVERLAP, 0)
Commit	Line	Data
51e0304c IM	1	/*
	2	* Only give sleepers 50% of their service deficit. This allows
	3	* them to run sooner, but does not allow tons of sleepers to
	4	* rip the spread apart.
	5	*/
	6	SCHED_FEAT(GENTLE_FAIR_SLEEPERS, 1)
e26af0e8	7
e26af0e8 PZ	8	/*
	9	* Place new tasks ahead so that they do not starve already running
	10	* tasks
	11	*/
f00b45c1	12	SCHED_FEAT(START_DEBIT, 1)
e26af0e8	13
e26af0e8 PZ	14	/*
	15	* Based on load and program behaviour, see if it makes sense to place
	16	* a newly woken task on the same cpu as the task that woke it --
	17	* improve cache locality. Typically used with SYNC wakeups as
	18	* generated by pipes and the like, see also SYNC_WAKEUPS.
	19	*/
f00b45c1	20	SCHED_FEAT(AFFINE_WAKEUPS, 1)
e26af0e8 PZ	21
	22	/*
	23	* Prefer to schedule the task we woke last (assuming it failed
	24	* wakeup-preemption), since its likely going to consume data we
	25	* touched, increases cache locality.
	26	*/
0ec9fab3	27	SCHED_FEAT(NEXT_BUDDY, 0)
e26af0e8 PZ	28
	29	/*
	30	* Prefer to schedule the task that ran last (when we did
	31	* wake-preempt) as that likely will touch the same data, increases
	32	* cache locality.
	33	*/
	34	SCHED_FEAT(LAST_BUDDY, 1)
	35
	36	/*
	37	* Consider buddies to be cache hot, decreases the likelyness of a
	38	* cache buddy being migrated away, increases cache locality.
	39	*/
f00b45c1	40	SCHED_FEAT(CACHE_HOT_BUDDY, 1)
e26af0e8	41
8e6598af PZ	42	/*
	43	* Use arch dependent cpu power functions
	44	*/
	45	SCHED_FEAT(ARCH_POWER, 0)
	46
0c4b83da	47	SCHED_FEAT(HRTICK, 0)
f00b45c1	48	SCHED_FEAT(DOUBLE_TICK, 0)
efc2dead	49	SCHED_FEAT(LB_BIAS, 1)
e26af0e8 PZ	50
	51	/*
	52	* Spin-wait on mutex acquisition when the mutex owner is running on
	53	* another cpu -- assumes that when the owner is running, it will soon
	54	* release the lock. Decreases scheduling overhead.
	55	*/
0d66bf6d	56	SCHED_FEAT(OWNER_SPIN, 1)
aa483808 VP	57
aa483808 VP	58	/*
095c0aa8	59	* Decrement CPU power based on time not spent running tasks
aa483808	60	*/
095c0aa8	61	SCHED_FEAT(NONTASK_POWER, 1)
317f3941 PZ	62
	63	/*
	64	* Queue remote wakeups on the target CPU and process them
	65	* using the scheduler IPI. Reduces rq->lock contention/bounces.
	66	*/
	67	SCHED_FEAT(TTWU_QUEUE, 1)
e3589f6c PZ	68
e3589f6c PZ	69	SCHED_FEAT(FORCE_SD_OVERLAP, 0)