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| author | Qais Yousef <qais.yousef@arm.com> | 2022-08-04 17:36:03 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-27 12:01:18 +0300 |
| commit | 244226035a1f9b2b6c326e55ae5188fab4f428cb (patch) | |
| tree | 54019e47494836ed44cee16a4b8bd86dc41a6379 /kernel/sched/fair.c | |
| parent | b48e16a69792b5dc4a09d6807369d11b2970cc36 (diff) | |
| download | linux-244226035a1f9b2b6c326e55ae5188fab4f428cb.tar.xz | |
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 <hsiang023167@gmail.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index db6174b989ed..c8eb5ff81084 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7169,6 +7169,8 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) { struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask); unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX; + unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0; + unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024; struct root_domain *rd = this_rq()->rd; int cpu, best_energy_cpu, target = -1; struct sched_domain *sd; @@ -7201,6 +7203,8 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) for (; pd; pd = pd->next) { unsigned long cpu_cap, cpu_thermal_cap, util; unsigned long cur_delta, max_spare_cap = 0; + unsigned long rq_util_min, rq_util_max; + unsigned long util_min, util_max; bool compute_prev_delta = false; int max_spare_cap_cpu = -1; unsigned long base_energy; @@ -7237,8 +7241,26 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) * much capacity we can get out of the CPU; this is * aligned with sched_cpu_util(). */ - util = uclamp_rq_util_with(cpu_rq(cpu), util, p); - if (!fits_capacity(util, cpu_cap)) + if (uclamp_is_used()) { + if (uclamp_rq_is_idle(cpu_rq(cpu))) { + util_min = p_util_min; + util_max = p_util_max; + } else { + /* + * Open code uclamp_rq_util_with() except for + * the clamp() part. Ie: apply max aggregation + * only. util_fits_cpu() logic requires to + * operate on non clamped util but must use the + * max-aggregated uclamp_{min, max}. + */ + rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN); + rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX); + + util_min = max(rq_util_min, p_util_min); + util_max = max(rq_util_max, p_util_max); + } + } + if (!util_fits_cpu(util, util_min, util_max, cpu)) continue; lsub_positive(&cpu_cap, util); |