From: Peter Zijlstra <peterz@infradead.org>
To: torvalds@linux-foundation.org, mingo@kernel.org, bp@alien8.de,
tglx@linutronix.de, luto@kernel.org, namit@vmware.com,
peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, Nadav Amit <nadav.amit@gmail.com>
Subject: [PATCH 5/5] x86/percpu, sched/fair: Avoid local_clock()
Date: Wed, 27 Feb 2019 11:12:57 +0100 [thread overview]
Message-ID: <20190227101544.581505206@infradead.org> (raw)
In-Reply-To: 20190227101252.413192716@infradead.org
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;
next prev parent reply other threads:[~2019-02-27 10:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-27 10:12 [PATCH 0/5] x86/percpu semantics and fixes Peter Zijlstra
2019-02-27 10:12 ` [PATCH 1/5] x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}() Peter Zijlstra
2019-02-27 16:14 ` Linus Torvalds
2019-02-27 16:48 ` Peter Zijlstra
2019-02-27 17:17 ` Linus Torvalds
2019-02-27 17:34 ` Peter Zijlstra
2019-02-27 17:38 ` Linus Torvalds
2019-02-27 17:57 ` Nadav Amit
2019-02-27 18:55 ` Nadav Amit
2019-02-27 19:41 ` Linus Torvalds
2019-03-08 13:35 ` Peter Zijlstra
2019-02-27 10:12 ` [PATCH 2/5] x86/percpu: Relax smp_processor_id() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 3/5] x86/percpu, x86/irq: Relax {set,get}_irq_regs() Peter Zijlstra
2019-02-27 10:12 ` [PATCH 4/5] x86/percpu, x86/tlb: Relax cpu_tlbstate accesses Peter Zijlstra
2019-02-27 10:12 ` Peter Zijlstra [this message]
2019-02-27 10:24 ` [PATCH 6/5] x86/percpu: Optimize raw_cpu_xchg() Peter Zijlstra
2019-02-27 14:43 ` Peter Zijlstra
2019-02-27 23:16 ` [PATCH 0/5] x86/percpu semantics and fixes Nadav Amit
2019-03-08 14:50 ` Peter Zijlstra
2019-03-08 19:35 ` Nadav Amit
2019-03-08 20:56 ` Peter Zijlstra
2019-03-10 12:46 ` Peter Zijlstra
2019-03-08 22:48 ` Peter Zijlstra
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