From 8dc2d993cf1aea578d947e34ea2d5c6ffd1644e4 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 27 Feb 2019 10:27:58 +0100 Subject: [PATCH] x86/percpu, sched/fair: Avoid local_clock() Nadav reported that code-gen changed because of the this_cpu_*() constraints, avoid this for select_idle_cpu() because that runs with preemption (and IRQs) disabled anyway. Reported-by: Nadav Amit Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f35930f5e528..8591529e1753 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6189,6 +6189,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t u64 time, cost; s64 delta; int cpu, nr = INT_MAX; + int this = smp_processor_id(); this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); if (!this_sd) @@ -6212,7 +6213,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t nr = 4; } - time = local_clock(); + time = cpu_clock(this); for_each_cpu_wrap(cpu, sched_domain_span(sd), target) { if (!--nr) @@ -6223,7 +6224,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t break; } - time = local_clock() - time; + time = cpu_clock(this) - time; cost = this_sd->avg_scan_cost; delta = (s64)(time - cost) / 8; this_sd->avg_scan_cost += delta;