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refscale: Add this_cpu_inc() readers

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This commit adds refscale readers based on this_cpu_inc() and
this_cpu_inc() ("refscale.scale_type=percpuinc").  On my x86 laptop,
these are about 4.5ns per pair.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This commit is contained in:
Paul E. McKenney 2025-11-02 14:49:45 -08:00 committed by Frederic Weisbecker
parent 057df3eaca
commit bdba8330ad
1 changed files with 32 additions and 4 deletions
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36
kernel/rcu/refscale.c
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@ -323,6 +323,9 @@ static const struct ref_scale_ops rcu_trace_ops = {
// Definitions for reference count
static atomic_t refcnt;
// Definitions acquire-release.
static DEFINE_PER_CPU(unsigned long, test_acqrel);
static void ref_refcnt_section(const int nloops)
{
int i;
@ -351,6 +354,34 @@ static const struct ref_scale_ops refcnt_ops = {
.name = "refcnt"
};
static void ref_percpuinc_section(const int nloops)
{
int i;
for (i = nloops; i >= 0; i--) {
this_cpu_inc(test_acqrel);
this_cpu_dec(test_acqrel);
}
}
static void ref_percpuinc_delay_section(const int nloops, const int udl, const int ndl)
{
int i;
for (i = nloops; i >= 0; i--) {
this_cpu_inc(test_acqrel);
un_delay(udl, ndl);
this_cpu_dec(test_acqrel);
}
}
static const struct ref_scale_ops percpuinc_ops = {
.init = rcu_sync_scale_init,
.readsection = ref_percpuinc_section,
.delaysection = ref_percpuinc_delay_section,
.name = "percpuinc"
};
// Definitions for rwlock
static rwlock_t test_rwlock;
@ -494,9 +525,6 @@ static const struct ref_scale_ops lock_irq_ops = {
.name = "lock-irq"
};
// Definitions acquire-release.
static DEFINE_PER_CPU(unsigned long, test_acqrel);
static void ref_acqrel_section(const int nloops)
{
unsigned long x;
@ -1291,7 +1319,7 @@ ref_scale_init(void)
static const struct ref_scale_ops *scale_ops[] = {
&rcu_ops, &srcu_ops, &srcu_fast_ops, RCU_TRACE_OPS RCU_TASKS_OPS
&refcnt_ops, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops,
&acqrel_ops, &sched_clock_ops, &clock_ops, &jiffies_ops,
&percpuinc_ops, &acqrel_ops, &sched_clock_ops, &clock_ops, &jiffies_ops,
&preempt_ops, &bh_ops, &irq_ops, &irqsave_ops,
&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,
};