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authorPeter Zijlstra <peterz@infradead.org>2019-02-27 10:27:58 +0100
committerIngo Molnar <mingo@kernel.org>2019-06-17 12:43:43 +0200
commit8dc2d993cf1aea578d947e34ea2d5c6ffd1644e4 (patch)
treed6eaa5e880f797ca01c677175df65031a90ca032 /kernel/sched
parent602447f95461469e20c81254c1c08be23a46fe53 (diff)
downloadlinux-8dc2d993cf1aea578d947e34ea2d5c6ffd1644e4.tar.bz2
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 <nadav.amit@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/fair.c5
1 files 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;