From 244226035a1f9b2b6c326e55ae5188fab4f428cb Mon Sep 17 00:00:00 2001 From: Qais Yousef Date: Thu, 4 Aug 2022 15:36:03 +0100 Subject: sched/uclamp: Fix fits_capacity() check in feec() As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024, it'll always pick the previous CPU because fits_capacity() will always return false in this case. The new util_fits_cpu() logic should handle this correctly for us beside more corner cases where similar failures could occur, like when using UCLAMP_MAX. We open code uclamp_rq_util_with() except for the clamp() part, util_fits_cpu() needs the 'raw' values to be passed to it. Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp value for the rq. Makes the code more readable and ensures the right rules (use READ_ONCE/WRITE_ONCE) are respected transparently. [1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions") Reported-by: Yun Hsiang Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com --- kernel/sched/sched.h | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) (limited to 'kernel/sched/sched.h') diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 0ab091b9d91b..d6d488e8eb55 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2979,6 +2979,23 @@ static inline unsigned long cpu_util_rt(struct rq *rq) #ifdef CONFIG_UCLAMP_TASK unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id); +static inline unsigned long uclamp_rq_get(struct rq *rq, + enum uclamp_id clamp_id) +{ + return READ_ONCE(rq->uclamp[clamp_id].value); +} + +static inline void uclamp_rq_set(struct rq *rq, enum uclamp_id clamp_id, + unsigned int value) +{ + WRITE_ONCE(rq->uclamp[clamp_id].value, value); +} + +static inline bool uclamp_rq_is_idle(struct rq *rq) +{ + return rq->uclamp_flags & UCLAMP_FLAG_IDLE; +} + /** * uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values. * @rq: The rq to clamp against. Must not be NULL. @@ -3014,12 +3031,12 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, * Ignore last runnable task's max clamp, as this task will * reset it. Similarly, no need to read the rq's min clamp. */ - if (rq->uclamp_flags & UCLAMP_FLAG_IDLE) + if (uclamp_rq_is_idle(rq)) goto out; } - min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value)); - max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value)); + min_util = max_t(unsigned long, min_util, uclamp_rq_get(rq, UCLAMP_MIN)); + max_util = max_t(unsigned long, max_util, uclamp_rq_get(rq, UCLAMP_MAX)); out: /* * Since CPU's {min,max}_util clamps are MAX aggregated considering @@ -3082,6 +3099,25 @@ static inline bool uclamp_is_used(void) { return false; } + +static inline unsigned long uclamp_rq_get(struct rq *rq, + enum uclamp_id clamp_id) +{ + if (clamp_id == UCLAMP_MIN) + return 0; + + return SCHED_CAPACITY_SCALE; +} + +static inline void uclamp_rq_set(struct rq *rq, enum uclamp_id clamp_id, + unsigned int value) +{ +} + +static inline bool uclamp_rq_is_idle(struct rq *rq) +{ + return false; +} #endif /* CONFIG_UCLAMP_TASK */ #ifdef CONFIG_HAVE_SCHED_AVG_IRQ -- cgit v1.2.3