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Date: Wed, 15 Jun 2016 15:28:26 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
bobby.prani@...il.com,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 6/8] torture: Make waketorture always hotplug the same CPU
This commit causes waketorture to always hotplug the same CPU,
namely, the highest-numbered CPU that can be hotplugged. This
will be used by later commits to force race conditions with
higher probability.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/waketorture.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 85 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/waketorture.c b/kernel/rcu/waketorture.c
index bf04c65296bd..8568688607ac 100644
--- a/kernel/rcu/waketorture.c
+++ b/kernel/rcu/waketorture.c
@@ -74,6 +74,7 @@ MODULE_PARM_DESC(torture_type, "Type of wait to torture (sti, stui, ...)");
static int nrealwaiters;
static struct task_struct **waiter_tasks;
static struct task_struct *stats_task;
+static struct task_struct *onoff_task;
/* Yes, these cache-thrash, and it is inherent to the concurrency design. */
static bool *waiter_done; /* Waiter is done, don't wake. */
@@ -85,6 +86,18 @@ static DEFINE_MUTEX(waiter_mutex);
static DEFINE_PER_CPU(u64, waiter_cputime); /* Nanoseconds. */
static u64 starttime;
+static int onoff_cpu = -1;
+static long n_offline_attempts;
+static long n_offline_successes;
+static unsigned long sum_offline;
+static int min_offline = -1;
+static int max_offline;
+static long n_online_attempts;
+static long n_online_successes;
+static unsigned long sum_online;
+static int min_online = -1;
+static int max_online;
+
static int torture_runnable = IS_ENABLED(MODULE);
module_param(torture_runnable, int, 0444);
MODULE_PARM_DESC(torture_runnable, "Start waketorture at boot");
@@ -219,6 +232,67 @@ static int wake_torture_waiter(void *arg)
}
/*
+ * Find a hotpluggable CPU and repeatedly take it online and offline.
+ */
+static int wake_torture_onoff(void *args)
+{
+ int cpu;
+
+ VERBOSE_TOROUT_STRING("wake_torture_onoff task started");
+ if (onoff_holdoff > 0) {
+ VERBOSE_TOROUT_STRING("wake_torture_onoff begin holdoff");
+ schedule_timeout_interruptible(onoff_holdoff * HZ);
+ VERBOSE_TOROUT_STRING("wake_torture_onoff end holdoff");
+ }
+ for_each_online_cpu(cpu) {
+ if (cpu_is_hotpluggable(cpu))
+ onoff_cpu = cpu;
+ }
+ pr_alert("%s" TORTURE_FLAG " wake_torture_onoff: onoff_cpu: %d\n", torture_type, onoff_cpu);
+ if (onoff_cpu < 0)
+ VERBOSE_TOROUT_STRING("wake_torture_onoff: no hotpluggable CPUs!");
+ while (!torture_must_stop() && onoff_cpu >= 0) {
+ if (!torture_offline(onoff_cpu,
+ &n_offline_attempts, &n_offline_successes,
+ &sum_offline, &min_offline, &max_offline))
+ torture_online(onoff_cpu,
+ &n_online_attempts, &n_online_successes,
+ &sum_online, &min_online, &max_online);
+ schedule_timeout_interruptible(onoff_interval);
+ }
+ torture_kthread_stopping("wake_torture_onoff");
+ return 0;
+}
+
+/*
+ * Initiate waketorture-specific online-offline handling, which
+ * focuses on a single CPU.
+ */
+static int wake_torture_onoff_init(void)
+{
+ int ret = 0;
+
+ if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+ return ret;
+ if (onoff_interval <= 0)
+ return 0;
+ ret = torture_create_kthread(wake_torture_onoff, NULL, onoff_task);
+ return ret;
+}
+
+/*
+ * Clean up after waketorture-specific online-offline handling.
+ */
+static void wake_torture_onoff_cleanup(void)
+{
+ if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
+ return;
+ VERBOSE_TOROUT_STRING("Stopping wake_torture_onoff task");
+ kthread_stop(onoff_task);
+ onoff_task = NULL;
+}
+
+/*
* Print torture statistics. Caller must ensure that there is only one
* call to this function at a given time!!! This is normally accomplished
* by relying on the module system to only have one copy of the module
@@ -265,9 +339,14 @@ wake_torture_stats_print(void)
timetot += READ_ONCE(per_cpu(waiter_cputime, i));
timetot /= nr_cpu_ids;
timetot /= timediff;
- pr_alert("%s" TORTURE_FLAG " timediff: %llu utilization: %llu.%llu nr_cpu_ids: %d\n",
+ pr_alert("%s" TORTURE_FLAG " timediff: %llu utilization: %llu.%llu nr_cpu_ids: %d onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d)\n",
torture_type, timediff,
- timetot / 1000ULL, timetot % 1000ULL, nr_cpu_ids);
+ timetot / 1000ULL, timetot % 1000ULL, nr_cpu_ids,
+ n_online_successes, n_online_attempts,
+ n_offline_successes, n_offline_attempts,
+ min_online, max_online,
+ min_offline, max_offline,
+ sum_online, sum_offline, HZ);
}
/*
@@ -307,6 +386,9 @@ wake_torture_cleanup(void)
(void)torture_cleanup_begin();
+ if (onoff_task)
+ wake_torture_onoff_cleanup();
+
if (waiter_tasks) {
for (i = 0; i < nrealwaiters; i++)
torture_stop_kthread(wake_torture_waiter,
@@ -414,7 +496,7 @@ wake_torture_init(void)
firsterr = torture_shutdown_init(shutdown_secs, wake_torture_cleanup);
if (firsterr)
goto unwind;
- firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
+ firsterr = wake_torture_onoff_init();
if (firsterr)
goto unwind;
torture_init_end();
--
2.5.2
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