From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH rcu 1/7] refscale: Add measurement of clock readout
Date: Wed, 21 Jul 2021 14:04:35 -0700 [thread overview]
Message-ID: <20210721210441.796995-1-paulmck@kernel.org> (raw)
In-Reply-To: <20210721210421.GA788053@paulmck-ThinkPad-P17-Gen-1>
This commit adds a "clock" type to refscale, which checks the performance
of ktime_get_real_fast_ns(). Use the "clocksource=" kernel boot parameter
to select the underlying clock source.
[ paulmck: Work around compiler false positive per kernel test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/refscale.c | 37 ++++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index d998a76fb5422..cba737cb246e8 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -467,6 +467,41 @@ static struct ref_scale_ops acqrel_ops = {
.name = "acqrel"
};
+static volatile u64 stopopts;
+
+static void ref_clock_section(const int nloops)
+{
+ u64 x = 0;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x += ktime_get_real_fast_ns();
+ }
+ preempt_enable();
+ stopopts = x;
+}
+
+static void ref_clock_delay_section(const int nloops, const int udl, const int ndl)
+{
+ u64 x = 0;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x += ktime_get_real_fast_ns();
+ un_delay(udl, ndl);
+ }
+ preempt_enable();
+ stopopts = x;
+}
+
+static struct ref_scale_ops clock_ops = {
+ .readsection = ref_clock_section,
+ .delaysection = ref_clock_delay_section,
+ .name = "clock"
+};
+
static void rcu_scale_one_reader(void)
{
if (readdelay <= 0)
@@ -759,7 +794,7 @@ ref_scale_init(void)
int firsterr = 0;
static struct ref_scale_ops *scale_ops[] = {
&rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops, &refcnt_ops, &rwlock_ops,
- &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
+ &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops,
};
if (!torture_init_begin(scale_type, verbose))
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2021-07-21 21:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 21:04 [PATCH rcu 0/7] Torture-test updates for v5.15 Paul E. McKenney
2021-07-21 21:04 ` Paul E. McKenney [this message]
2021-07-28 17:38 ` [PATCH v2 rcu 1/7] refscale: Add measurement of clock readout Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 2/7] rcutorture: Preempt rather than block when testing task stalls Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 3/7] rcuscale: Console output claims too few grace periods Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 4/7] locktorture: Mark statistics data races Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 5/7] locktorture: Count lock readers Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 6/7] scftorture: Add RPC-like IPI tests Paul E. McKenney
2021-07-21 21:04 ` [PATCH rcu 7/7] scftorture: Avoid NULL pointer exception on early exit Paul E. McKenney
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