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-rw-r--r--kernel/locking/Makefile1
-rw-r--r--kernel/locking/lock_events.c153
-rw-r--r--kernel/locking/lock_events.h10
-rw-r--r--kernel/locking/qspinlock_stat.h141
4 files changed, 173 insertions, 132 deletions
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 1af83e9ce57d..6fe2f333aecb 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -28,3 +28,4 @@ obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o
obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o
obj-$(CONFIG_LOCK_TORTURE_TEST) += locktorture.o
obj-$(CONFIG_WW_MUTEX_SELFTEST) += test-ww_mutex.o
+obj-$(CONFIG_LOCK_EVENT_COUNTS) += lock_events.o
diff --git a/kernel/locking/lock_events.c b/kernel/locking/lock_events.c
new file mode 100644
index 000000000000..71c36d1fb834
--- /dev/null
+++ b/kernel/locking/lock_events.c
@@ -0,0 +1,153 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Authors: Waiman Long <waiman.long@hpe.com>
+ */
+
+/*
+ * Collect locking event counts
+ */
+#include <linux/debugfs.h>
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/fs.h>
+
+#include "lock_events.h"
+
+#undef LOCK_EVENT
+#define LOCK_EVENT(name) [LOCKEVENT_ ## name] = #name,
+
+#define LOCK_EVENTS_DIR "lock_event_counts"
+
+/*
+ * When CONFIG_LOCK_EVENT_COUNTS is enabled, event counts of different
+ * types of locks will be reported under the <debugfs>/lock_event_counts/
+ * directory. See lock_events_list.h for the list of available locking
+ * events.
+ *
+ * Writing to the special ".reset_counts" file will reset all the above
+ * locking event counts. This is a very slow operation and so should not
+ * be done frequently.
+ *
+ * These event counts are implemented as per-cpu variables which are
+ * summed and computed whenever the corresponding debugfs files are read. This
+ * minimizes added overhead making the counts usable even in a production
+ * environment.
+ */
+static const char * const lockevent_names[lockevent_num + 1] = {
+
+#include "lock_events_list.h"
+
+ [LOCKEVENT_reset_cnts] = ".reset_counts",
+};
+
+/*
+ * Per-cpu counts
+ */
+DEFINE_PER_CPU(unsigned long, lockevents[lockevent_num]);
+
+/*
+ * The lockevent_read() function can be overridden.
+ */
+ssize_t __weak 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;
+
+ /*
+ * 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);
+ len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
+
+ return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+/*
+ * Function to handle write request
+ *
+ * When idx = reset_cnts, reset all the counts.
+ */
+static ssize_t lockevent_write(struct file *file, const char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ int cpu;
+
+ /*
+ * Get the counter ID stored in file->f_inode->i_private
+ */
+ if ((long)file_inode(file)->i_private != LOCKEVENT_reset_cnts)
+ return count;
+
+ for_each_possible_cpu(cpu) {
+ int i;
+ unsigned long *ptr = per_cpu_ptr(lockevents, cpu);
+
+ for (i = 0 ; i < lockevent_num; i++)
+ WRITE_ONCE(ptr[i], 0);
+ }
+ return count;
+}
+
+/*
+ * Debugfs data structures
+ */
+static const struct file_operations fops_lockevent = {
+ .read = lockevent_read,
+ .write = lockevent_write,
+ .llseek = default_llseek,
+};
+
+/*
+ * Initialize debugfs for the locking event counts.
+ */
+static int __init init_lockevent_counts(void)
+{
+ struct dentry *d_counts = debugfs_create_dir(LOCK_EVENTS_DIR, NULL);
+ int i;
+
+ if (!d_counts)
+ goto out;
+
+ /*
+ * Create the debugfs files
+ *
+ * As reading from and writing to the stat files can be slow, only
+ * root is allowed to do the read/write to limit impact to system
+ * performance.
+ */
+ for (i = 0; i < lockevent_num; i++)
+ if (!debugfs_create_file(lockevent_names[i], 0400, d_counts,
+ (void *)(long)i, &fops_lockevent))
+ goto fail_undo;
+
+ if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
+ d_counts, (void *)(long)LOCKEVENT_reset_cnts,
+ &fops_lockevent))
+ goto fail_undo;
+
+ return 0;
+fail_undo:
+ debugfs_remove_recursive(d_counts);
+out:
+ pr_warn("Could not create '%s' debugfs entries\n", LOCK_EVENTS_DIR);
+ return -ENOMEM;
+}
+fs_initcall(init_lockevent_counts);
diff --git a/kernel/locking/lock_events.h b/kernel/locking/lock_events.h
index 4009e07b474a..feb1acc54611 100644
--- a/kernel/locking/lock_events.h
+++ b/kernel/locking/lock_events.h
@@ -13,6 +13,9 @@
* Authors: Waiman Long <longman@redhat.com>
*/
+#ifndef __LOCKING_LOCK_EVENTS_H
+#define __LOCKING_LOCK_EVENTS_H
+
enum lock_events {
#include "lock_events_list.h"
@@ -21,7 +24,7 @@ enum lock_events {
LOCKEVENT_reset_cnts = lockevent_num,
};
-#ifdef CONFIG_QUEUED_LOCK_STAT
+#ifdef CONFIG_LOCK_EVENT_COUNTS
/*
* Per-cpu counters
*/
@@ -46,10 +49,11 @@ static inline void __lockevent_add(enum lock_events event, int inc)
#define lockevent_add(ev, c) __lockevent_add(LOCKEVENT_ ##ev, c)
-#else /* CONFIG_QUEUED_LOCK_STAT */
+#else /* CONFIG_LOCK_EVENT_COUNTS */
#define lockevent_inc(ev)
#define lockevent_add(ev, c)
#define lockevent_cond_inc(ev, c)
-#endif /* CONFIG_QUEUED_LOCK_STAT */
+#endif /* CONFIG_LOCK_EVENT_COUNTS */
+#endif /* __LOCKING_LOCK_EVENTS_H */
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index 1db5b375fcf4..54152670ff24 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -9,76 +9,29 @@
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
- * Authors: Waiman Long <waiman.long@hpe.com>
+ * Authors: Waiman Long <longman@redhat.com>
*/
-/*
- * When queued spinlock statistical counters are enabled, the following
- * debugfs files will be created for reporting the counter values:
- *
- * <debugfs>/qlockstat/
- * pv_hash_hops - average # of hops per hashing operation
- * pv_kick_unlock - # of vCPU kicks issued at unlock time
- * pv_kick_wake - # of vCPU kicks used for computing pv_latency_wake
- * pv_latency_kick - average latency (ns) of vCPU kick operation
- * pv_latency_wake - average latency (ns) from vCPU kick to wakeup
- * pv_lock_stealing - # of lock stealing operations
- * pv_spurious_wakeup - # of spurious wakeups in non-head vCPUs
- * pv_wait_again - # of wait's after a queue head vCPU kick
- * pv_wait_early - # of early vCPU wait's
- * pv_wait_head - # of vCPU wait's at the queue head
- * pv_wait_node - # of vCPU wait's at a non-head queue node
- * lock_pending - # of locking operations via pending code
- * lock_slowpath - # of locking operations via MCS lock queue
- * lock_use_node2 - # of locking operations that use 2nd per-CPU node
- * lock_use_node3 - # of locking operations that use 3rd per-CPU node
- * lock_use_node4 - # of locking operations that use 4th per-CPU node
- * lock_no_node - # of locking operations without using per-CPU node
- *
- * Subtracting lock_use_node[234] from lock_slowpath will give you
- * lock_use_node1.
- *
- * Writing to the special ".reset_counts" file will reset all the above
- * counter values.
- *
- * These statistical counters are implemented as per-cpu variables which are
- * summed and computed whenever the corresponding debugfs files are read. This
- * minimizes added overhead making the counters usable even in a production
- * environment.
- *
- * There may be slight difference between pv_kick_wake and pv_kick_unlock.
- */
#include "lock_events.h"
-#ifdef CONFIG_QUEUED_LOCK_STAT
+#ifdef CONFIG_LOCK_EVENT_COUNTS
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
/*
- * Collect pvqspinlock statistics
+ * Collect pvqspinlock locking event counts
*/
-#include <linux/debugfs.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/fs.h>
#define EVENT_COUNT(ev) lockevents[LOCKEVENT_ ## ev]
-#undef LOCK_EVENT
-#define LOCK_EVENT(name) [LOCKEVENT_ ## name] = #name,
-
-static const char * const lockevent_names[lockevent_num + 1] = {
-
-#include "lock_events_list.h"
-
- [LOCKEVENT_reset_cnts] = ".reset_counts",
-};
-
/*
- * Per-cpu counters
+ * PV specific per-cpu counter
*/
-DEFINE_PER_CPU(unsigned long, lockevents[lockevent_num]);
static DEFINE_PER_CPU(u64, pv_kick_time);
/*
- * Function to read and return the qlock statistical counter values
+ * Function to read and return the PV qspinlock counts.
*
* The following counters are handled specially:
* 1. pv_latency_kick
@@ -88,8 +41,8 @@ static DEFINE_PER_CPU(u64, pv_kick_time);
* 3. pv_hash_hops
* Average hops/hash = pv_hash_hops/pv_kick_unlock
*/
-static ssize_t lockevent_read(struct file *file, char __user *user_buf,
- size_t count, loff_t *ppos)
+ssize_t lockevent_read(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
{
char buf[64];
int cpu, id, len;
@@ -150,78 +103,6 @@ static ssize_t lockevent_read(struct file *file, char __user *user_buf,
}
/*
- * Function to handle write request
- *
- * When id = .reset_cnts, reset all the counter values.
- */
-static ssize_t lockevent_write(struct file *file, const char __user *user_buf,
- size_t count, loff_t *ppos)
-{
- int cpu;
-
- /*
- * Get the counter ID stored in file->f_inode->i_private
- */
- if ((long)file_inode(file)->i_private != LOCKEVENT_reset_cnts)
- return count;
-
- for_each_possible_cpu(cpu) {
- int i;
- unsigned long *ptr = per_cpu_ptr(lockevents, cpu);
-
- for (i = 0 ; i < lockevent_num; i++)
- WRITE_ONCE(ptr[i], 0);
- }
- return count;
-}
-
-/*
- * Debugfs data structures
- */
-static const struct file_operations fops_lockevent = {
- .read = lockevent_read,
- .write = lockevent_write,
- .llseek = default_llseek,
-};
-
-/*
- * Initialize debugfs for the qspinlock statistical counters
- */
-static int __init init_qspinlock_stat(void)
-{
- struct dentry *d_counts = debugfs_create_dir("qlockstat", NULL);
- int i;
-
- if (!d_counts)
- goto out;
-
- /*
- * Create the debugfs files
- *
- * As reading from and writing to the stat files can be slow, only
- * root is allowed to do the read/write to limit impact to system
- * performance.
- */
- for (i = 0; i < lockevent_num; i++)
- if (!debugfs_create_file(lockevent_names[i], 0400, d_counts,
- (void *)(long)i, &fops_lockevent))
- goto fail_undo;
-
- if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
- d_counts, (void *)(long)LOCKEVENT_reset_cnts,
- &fops_lockevent))
- goto fail_undo;
-
- return 0;
-fail_undo:
- debugfs_remove_recursive(d_counts);
-out:
- pr_warn("Could not create 'qlockstat' debugfs entries\n");
- return -ENOMEM;
-}
-fs_initcall(init_qspinlock_stat);
-
-/*
* PV hash hop count
*/
static inline void lockevent_pv_hop(int hopcnt)
@@ -260,8 +141,10 @@ static inline void __pv_wait(u8 *ptr, u8 val)
#define pv_kick(c) __pv_kick(c)
#define pv_wait(p, v) __pv_wait(p, v)
-#else /* CONFIG_QUEUED_LOCK_STAT */
+#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+
+#else /* CONFIG_LOCK_EVENT_COUNTS */
static inline void lockevent_pv_hop(int hopcnt) { }
-#endif /* CONFIG_QUEUED_LOCK_STAT */
+#endif /* CONFIG_LOCK_EVENT_COUNTS */
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-17 01:29:43 +0000