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sched/walt/core_ctl: do core control immediately

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The current code requires an execution of the core
control kthread in order to perform any pause/unpause
operations. Because the mechanism to pause or unpause
a cpu (halt) is only a bit-flip operation, this can
cause unnecessary delay in the unpause path.

Use spinlocks in halt, and call the main core control
functionality immediately from the walt_irq_work
context, eliminating this potential delay.

Change-Id: I74d82c445097c1074ad106501b101a06875da38e
Signed-off-by: Stephen Dickey <quic_dickey@quicinc.com>
This commit is contained in:
Stephen Dickey 2022-03-07 12:16:43 -08:00 committed by Rishabh Bhatnagar
parent 5a69b42f6b
commit 4240156af1
2 changed files with 10 additions and 6 deletions
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3
kernel/sched/walt/core_ctl.c
View File

@ -85,6 +85,7 @@ ATOMIC_NOTIFIER_HEAD(core_ctl_notifier);
static unsigned int last_nr_big;
static unsigned int get_active_cpu_count(const struct cluster_data *cluster);
static void __ref do_core_ctl(void);
/* ========================= sysfs interface =========================== */
@ -995,7 +996,7 @@ void core_ctl_check(u64 window_start)
wakeup |= eval_need(cluster);
if (wakeup)
wake_up_core_ctl_thread();
do_core_ctl();
core_ctl_call_notifier();
}

13
kernel/sched/walt/walt_halt.c
View File

@ -15,7 +15,8 @@
/* if a cpu is halting */
struct cpumask __cpu_halt_mask;
static DEFINE_MUTEX(halt_lock);
/* spin lock to allow calling from non-preemptible context */
static DEFINE_RAW_SPINLOCK(halt_lock);
struct halt_cpu_state {
u64 last_halt;
@ -359,8 +360,9 @@ int walt_halt_cpus(struct cpumask *cpus)
{
int ret = 0;
cpumask_t requested_cpus;
unsigned long flags;
mutex_lock(&halt_lock);
raw_spin_lock_irqsave(&halt_lock, flags);
cpumask_copy(&requested_cpus, cpus);
@ -380,7 +382,7 @@ int walt_halt_cpus(struct cpumask *cpus)
else
update_ref_counts(&requested_cpus, true);
unlock:
mutex_unlock(&halt_lock);
raw_spin_unlock_irqrestore(&halt_lock, flags);
return ret;
}
@ -397,8 +399,9 @@ int walt_start_cpus(struct cpumask *cpus)
{
int ret = 0;
cpumask_t requested_cpus;
unsigned long flags;
mutex_lock(&halt_lock);
raw_spin_lock_irqsave(&halt_lock, flags);
cpumask_copy(&requested_cpus, cpus);
update_ref_counts(&requested_cpus, false);
@ -414,7 +417,7 @@ int walt_start_cpus(struct cpumask *cpus)
update_ref_counts(&requested_cpus, true);
}
mutex_unlock(&halt_lock);
raw_spin_unlock_irqrestore(&halt_lock, flags);
return ret;
}