sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr()

The cpuacct_charge() and cpuacct_account_field() are called with
rq->lock held, and this means preemption(and IRQs) are indeed
disabled, so it is safe to use __this_cpu_*() to allow for better
code-generation.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200507031039.32615-1-songmuchun@bytedance.com

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 9fbb103..6448b04 100644 (file)
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -347,7 +347,7 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
        rcu_read_lock();
 
        for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
-               this_cpu_ptr(ca->cpuusage)->usages[index] += cputime;
+               __this_cpu_add(ca->cpuusage->usages[index], cputime);
 
        rcu_read_unlock();
 }
@@ -363,7 +363,7 @@ void cpuacct_account_field(struct task_struct *tsk, int index, u64 val)
 
        rcu_read_lock();
        for (ca = task_ca(tsk); ca != &root_cpuacct; ca = parent_ca(ca))
-               this_cpu_ptr(ca->cpustat)->cpustat[index] += val;
+               __this_cpu_add(ca->cpustat->cpustat[index], val);
        rcu_read_unlock();
 }