Commit 97450eb9 authored by Vincent Guittot's avatar Vincent Guittot Committed by Ingo Molnar
Browse files

sched/pelt: Remove shift of thermal clock 



The optional shift of the clock used by thermal/hw load avg has been
introduced to handle case where the signal was not always a high frequency
hw signal. Now that cpufreq provides a signal for firmware and
SW pressure, we can remove this exception and always keep this PELT signal
aligned with other signals.
Mark sysctl_sched_migration_cost boot parameter as deprecated

Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Reviewed-by: default avatarQais Yousef <qyousef@layalina.io>
Reviewed-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20240326091616.3696851-6-vincent.guittot@linaro.org
parent d4dbc991

Documentation/admin-guide/kernel-parameters.txt

+1 −0
Original line number Diff line number Diff line
@@ -5807,6 +5807,7 @@ 
			but is useful for debugging and performance tuning.



	sched_thermal_decay_shift=

			[Deprecated]

			[KNL, SMP] Set a decay shift for scheduler thermal

			pressure signal. Thermal pressure signal follows the

			default decay period of other scheduler pelt

kernel/sched/core.c

+1 −1
Original line number Diff line number Diff line
@@ -5680,7 +5680,7 @@ void sched_tick(void) 


	update_rq_clock(rq);

	hw_pressure = arch_scale_hw_pressure(cpu_of(rq));

	update_hw_load_avg(rq_clock_hw(rq), rq, hw_pressure);

	update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure);

	curr->sched_class->task_tick(rq, curr, 0);

	if (sched_feat(LATENCY_WARN))

		resched_latency = cpu_resched_latency(rq);

kernel/sched/fair.c

+2 −8
Original line number Diff line number Diff line
@@ -78,15 +78,9 @@ static unsigned int normalized_sysctl_sched_base_slice = 750000ULL; 


const_debug unsigned int sysctl_sched_migration_cost	= 500000UL;



int sched_hw_decay_shift;

static int __init setup_sched_thermal_decay_shift(char *str)

{

	int _shift = 0;



	if (kstrtoint(str, 0, &_shift))

		pr_warn("Unable to set scheduler thermal pressure decay shift parameter\n");



	sched_hw_decay_shift = clamp(_shift, 0, 10);

	pr_warn("Ignoring the deprecated sched_thermal_decay_shift= option\n");

	return 1;

}

__setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
@@ -9367,7 +9361,7 @@ static bool __update_blocked_others(struct rq *rq, bool *done) 


	decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |

		  update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |

		  update_hw_load_avg(rq_clock_hw(rq), rq, hw_pressure) |

		  update_hw_load_avg(now, rq, hw_pressure) |

		  update_irq_load_avg(rq, 0);



	if (others_have_blocked(rq))

kernel/sched/sched.h

+0 −18
Original line number Diff line number Diff line
@@ -1550,24 +1550,6 @@ static inline u64 rq_clock_task(struct rq *rq) 
	return rq->clock_task;

}



/**

 * By default the decay is the default pelt decay period.

 * The decay shift can change the decay period in

 * multiples of 32.

 *  Decay shift		Decay period(ms)

 *	0			32

 *	1			64

 *	2			128

 *	3			256

 *	4			512

 */

extern int sched_hw_decay_shift;



static inline u64 rq_clock_hw(struct rq *rq)

{

	return rq_clock_task(rq) >> sched_hw_decay_shift;

}



static inline void rq_clock_skip_update(struct rq *rq)

{

	lockdep_assert_rq_held(rq);