locking/lock_events: Make lock_events available for all archs & other locks (fb346fd9) · Commits · 戴 / test

arch/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -901,6 +901,16 @@ config HAVE_ARCH_PREL32_RELOCATIONS
		config ARCH_USE_MEMREMAP_PROT
		bool

		config LOCK_EVENT_COUNTS
		bool "Locking event counts collection"
		depends on DEBUG_FS
		depends on QUEUED_SPINLOCKS
		---help---
		Enable light-weight counting of various locking related events
		in the system with minimal performance impact. This reduces
		the chance of application behavior change because of timing
		differences. The counts are reported via debugfs.

		source "kernel/gcov/Kconfig"

		source "scripts/gcc-plugins/Kconfig"

arch/x86/Kconfig

+0 −8

Original line number	Diff line number	Diff line
		@@ -780,14 +780,6 @@ config PARAVIRT_SPINLOCKS

		If you are unsure how to answer this question, answer Y.

		config QUEUED_LOCK_STAT
		bool "Paravirt queued spinlock statistics"
		depends on PARAVIRT_SPINLOCKS && DEBUG_FS
		---help---
		Enable the collection of statistical data on the slowpath
		behavior of paravirtualized queued spinlocks and report
		them on debugfs.

		source "arch/x86/xen/Kconfig"

		config KVM_GUEST

kernel/locking/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

kernel/locking/lock_events.c

0 → 100644

+153 −0

Original line number	Diff line number	Diff line
		/* 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);

kernel/locking/lock_events.h

+7 −3

Original line number	Diff line number	Diff line
		@@ -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 */

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