1 files changed, 142 insertions, 0 deletions
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
new file mode 100644
index 000000000..e625bb410
--- /dev/null
+++ b/kernel/locking/qspinlock_stat.h
@@ -0,0 +1,142 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *
+ * Authors: Waiman Long <longman@redhat.com>
+ */
+
+#include "lock_events.h"
+
+#ifdef CONFIG_LOCK_EVENT_COUNTS
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+/*
+ * Collect pvqspinlock locking event counts
+ */
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/fs.h>
+
+#define EVENT_COUNT(ev)	lockevents[LOCKEVENT_ ## ev]
+
+/*
+ * PV specific per-cpu counter
+ */
+static DEFINE_PER_CPU(u64, pv_kick_time);
+
+/*
+ * Function to read and return the PV qspinlock counts.
+ *
+ * The following counters are handled specially:
+ * 1. pv_latency_kick
+ *    Average kick latency (ns) = pv_latency_kick/pv_kick_unlock
+ * 2. pv_latency_wake
+ *    Average wake latency (ns) = pv_latency_wake/pv_kick_wake
+ * 3. pv_hash_hops
+ *    Average hops/hash = pv_hash_hops/pv_kick_unlock
+ */
+ssize_t lockevent_read(struct file *file, char __user *user_buf,
+		       size_t count, loff_t *ppos)
+{
+	char buf[64];
+	int cpu, id, len;
+	u64 sum = 0, kicks = 0;
+
+	/*
+	 * Get the counter ID stored in file->f_inode->i_private
+	 */
+	id = (long)file_inode(file)->i_private;
+
+	if (id >= lockevent_num)
+		return -EBADF;
+
+	for_each_possible_cpu(cpu) {
+		sum += per_cpu(lockevents[id], cpu);
+		/*
+		 * Need to sum additional counters for some of them
+		 */
+		switch (id) {
+
+		case LOCKEVENT_pv_latency_kick:
+		case LOCKEVENT_pv_hash_hops:
+			kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu);
+			break;
+
+		case LOCKEVENT_pv_latency_wake:
+			kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu);
+			break;
+		}
+	}
+
+	if (id == LOCKEVENT_pv_hash_hops) {
+		u64 frac = 0;
+
+		if (kicks) {
+			frac = 100ULL * do_div(sum, kicks);
+			frac = DIV_ROUND_CLOSEST_ULL(frac, kicks);
+		}
+
+		/*
+		 * Return a X.XX decimal number
+		 */
+		len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
+			       sum, frac);
+	} else {
+		/*
+		 * Round to the nearest ns
+		 */
+		if ((id == LOCKEVENT_pv_latency_kick) ||
+		    (id == LOCKEVENT_pv_latency_wake)) {
+			if (kicks)
+				sum = DIV_ROUND_CLOSEST_ULL(sum, kicks);
+		}
+		len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
+	}
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+/*
+ * PV hash hop count
+ */
+static inline void lockevent_pv_hop(int hopcnt)
+{
+	this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt);
+}
+
+/*
+ * Replacement function for pv_kick()
+ */
+static inline void __pv_kick(int cpu)
+{
+	u64 start = sched_clock();
+
+	per_cpu(pv_kick_time, cpu) = start;
+	pv_kick(cpu);
+	this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start);
+}
+
+/*
+ * Replacement function for pv_wait()
+ */
+static inline void __pv_wait(u8 *ptr, u8 val)
+{
+	u64 *pkick_time = this_cpu_ptr(&pv_kick_time);
+
+	*pkick_time = 0;
+	pv_wait(ptr, val);
+	if (*pkick_time) {
+		this_cpu_add(EVENT_COUNT(pv_latency_wake),
+			     sched_clock() - *pkick_time);
+		lockevent_inc(pv_kick_wake);
+	}
+}
+
+#define pv_kick(c)	__pv_kick(c)
+#define pv_wait(p, v)	__pv_wait(p, v)
+
+#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+
+#else /* CONFIG_LOCK_EVENT_COUNTS */
+
+static inline void lockevent_pv_hop(int hopcnt)	{ }
+
+#endif /* CONFIG_LOCK_EVENT_COUNTS */