Messages in this thread Patch in this message | | | Date | Thu, 13 Jun 2019 15:54:49 +0200 | From | Peter Zijlstra <> | Subject | [PATCH v2 4/5] x86/percpu, sched/fair: Avoid local_clock() |
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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> --- kernel/sched/fair.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6160,6 +6160,7 @@ static int select_idle_cpu(struct task_s 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) @@ -6183,7 +6184,7 @@ static int select_idle_cpu(struct task_s nr = 4; } - time = local_clock(); + time = cpu_clock(this); for_each_cpu_wrap(cpu, sched_domain_span(sd), target) { if (!--nr) @@ -6194,7 +6195,7 @@ static int select_idle_cpu(struct task_s 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;
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