locking/qspinlock_stat: Introduce generic lockevent_*() counting APIs (ad53fa10) · Commits · EulixOS / Software / Kernel

kernel/locking/lock_events.h

0 → 100644

+55 −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 <longman@redhat.com>
		*/

		enum lock_events {

		#include "lock_events_list.h"

		lockevent_num, /* Total number of lock event counts */
		LOCKEVENT_reset_cnts = lockevent_num,
		};

		#ifdef CONFIG_QUEUED_LOCK_STAT
		/*
		* Per-cpu counters
		*/
		DECLARE_PER_CPU(unsigned long, lockevents[lockevent_num]);

		/*
		* Increment the PV qspinlock statistical counters
		*/
		static inline void __lockevent_inc(enum lock_events event, bool cond)
		{
		if (cond)
		__this_cpu_inc(lockevents[event]);
		}

		#define lockevent_inc(ev) __lockevent_inc(LOCKEVENT_ ##ev, true)
		#define lockevent_cond_inc(ev, c) __lockevent_inc(LOCKEVENT_ ##ev, c)

		static inline void __lockevent_add(enum lock_events event, int inc)
		{
		__this_cpu_add(lockevents[event], inc);
		}

		#define lockevent_add(ev, c) __lockevent_add(LOCKEVENT_ ##ev, c)

		#else /* CONFIG_QUEUED_LOCK_STAT */

		#define lockevent_inc(ev)
		#define lockevent_add(ev, c)
		#define lockevent_cond_inc(ev, c)

		#endif /* CONFIG_QUEUED_LOCK_STAT */

kernel/locking/lock_events_list.h

0 → 100644

+50 −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 <longman@redhat.com>
		*/

		#ifndef LOCK_EVENT
		#define LOCK_EVENT(name) LOCKEVENT_ ## name,
		#endif

		#ifdef CONFIG_QUEUED_SPINLOCKS
		#ifdef CONFIG_PARAVIRT_SPINLOCKS
		/*
		* Locking events for PV qspinlock.
		*/
		LOCK_EVENT(pv_hash_hops) /* Average # of hops per hashing operation */
		LOCK_EVENT(pv_kick_unlock) /* # of vCPU kicks issued at unlock time */
		LOCK_EVENT(pv_kick_wake) /* # of vCPU kicks for pv_latency_wake */
		LOCK_EVENT(pv_latency_kick) /* Average latency (ns) of vCPU kick */
		LOCK_EVENT(pv_latency_wake) /* Average latency (ns) of kick-to-wakeup */
		LOCK_EVENT(pv_lock_stealing) /* # of lock stealing operations */
		LOCK_EVENT(pv_spurious_wakeup) /* # of spurious wakeups in non-head vCPUs */
		LOCK_EVENT(pv_wait_again) /* # of wait's after queue head vCPU kick */
		LOCK_EVENT(pv_wait_early) /* # of early vCPU wait's */
		LOCK_EVENT(pv_wait_head) /* # of vCPU wait's at the queue head */
		LOCK_EVENT(pv_wait_node) /* # of vCPU wait's at non-head queue node */
		#endif /* CONFIG_PARAVIRT_SPINLOCKS */

		/*
		* Locking events for qspinlock
		*
		* Subtracting lock_use_node[234] from lock_slowpath will give you
		* lock_use_node1.
		*/
		LOCK_EVENT(lock_pending) /* # of locking ops via pending code */
		LOCK_EVENT(lock_slowpath) /* # of locking ops via MCS lock queue */
		LOCK_EVENT(lock_use_node2) /* # of locking ops that use 2nd percpu node */
		LOCK_EVENT(lock_use_node3) /* # of locking ops that use 3rd percpu node */
		LOCK_EVENT(lock_use_node4) /* # of locking ops that use 4th percpu node */
		LOCK_EVENT(lock_no_node) /* # of locking ops w/o using percpu node */
		#endif /* CONFIG_QUEUED_SPINLOCKS */

kernel/locking/qspinlock.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -395,7 +395,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
		* 0,1,0 -> 0,0,1
		*/
		clear_pending_set_locked(lock);
		qstat_inc(qstat_lock_pending, true);
		lockevent_inc(lock_pending);
		return;

		/*
		@@ -403,7 +403,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
		* queuing.
		*/
		queue:
		qstat_inc(qstat_lock_slowpath, true);
		lockevent_inc(lock_slowpath);
		pv_queue:
		node = this_cpu_ptr(&qnodes[0].mcs);
		idx = node->count++;
		@@ -419,7 +419,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
		* simple enough.
		*/
		if (unlikely(idx >= MAX_NODES)) {
		qstat_inc(qstat_lock_no_node, true);
		lockevent_inc(lock_no_node);
		while (!queued_spin_trylock(lock))
		cpu_relax();
		goto release;
		@@ -430,7 +430,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
		/*
		* Keep counts of non-zero index values:
		*/
		qstat_inc(qstat_lock_use_node2 + idx - 1, idx);
		lockevent_cond_inc(lock_use_node2 + idx - 1, idx);

		/*
		* Ensure that we increment the head node->count before initialising

kernel/locking/qspinlock_paravirt.h

+10 −9

Original line number	Diff line number	Diff line
		@@ -89,7 +89,7 @@ static inline bool pv_hybrid_queued_unfair_trylock(struct qspinlock *lock)

		if (!(val & _Q_LOCKED_PENDING_MASK) &&
		(cmpxchg_acquire(&lock->locked, 0, _Q_LOCKED_VAL) == 0)) {
		qstat_inc(qstat_pv_lock_stealing, true);
		lockevent_inc(pv_lock_stealing);
		return true;
		}
		if (!(val & _Q_TAIL_MASK) \|\| (val & _Q_PENDING_MASK))
		@@ -219,7 +219,7 @@ static struct qspinlock *pv_hash(struct qspinlock lock, struct pv_node *node)
		hopcnt++;
		if (!cmpxchg(&he->lock, NULL, lock)) {
		WRITE_ONCE(he->node, node);
		qstat_hop(hopcnt);
		lockevent_pv_hop(hopcnt);
		return &he->lock;
		}
		}
		@@ -320,8 +320,8 @@ static void pv_wait_node(struct mcs_spinlock node, struct mcs_spinlock prev)
		smp_store_mb(pn->state, vcpu_halted);

		if (!READ_ONCE(node->locked)) {
		qstat_inc(qstat_pv_wait_node, true);
		qstat_inc(qstat_pv_wait_early, wait_early);
		lockevent_inc(pv_wait_node);
		lockevent_cond_inc(pv_wait_early, wait_early);
		pv_wait(&pn->state, vcpu_halted);
		}

		@@ -339,7 +339,8 @@ static void pv_wait_node(struct mcs_spinlock node, struct mcs_spinlock prev)
		* So it is better to spin for a while in the hope that the
		* MCS lock will be released soon.
		*/
		qstat_inc(qstat_pv_spurious_wakeup, !READ_ONCE(node->locked));
		lockevent_cond_inc(pv_spurious_wakeup,
		!READ_ONCE(node->locked));
		}

		/*
		@@ -416,7 +417,7 @@ pv_wait_head_or_lock(struct qspinlock lock, struct mcs_spinlock node)
		/*
		* Tracking # of slowpath locking operations
		*/
		qstat_inc(qstat_lock_slowpath, true);
		lockevent_inc(lock_slowpath);

		for (;; waitcnt++) {
		/*
		@@ -464,8 +465,8 @@ pv_wait_head_or_lock(struct qspinlock lock, struct mcs_spinlock node)
		}
		}
		WRITE_ONCE(pn->state, vcpu_hashed);
		qstat_inc(qstat_pv_wait_head, true);
		qstat_inc(qstat_pv_wait_again, waitcnt);
		lockevent_inc(pv_wait_head);
		lockevent_cond_inc(pv_wait_again, waitcnt);
		pv_wait(&lock->locked, _Q_SLOW_VAL);

		/*
		@@ -528,7 +529,7 @@ __pv_queued_spin_unlock_slowpath(struct qspinlock *lock, u8 locked)
		* vCPU is harmless other than the additional latency in completing
		* the unlock.
		*/
		qstat_inc(qstat_pv_kick_unlock, true);
		lockevent_inc(pv_kick_unlock);
		pv_kick(node->cpu);
		}

kernel/locking/qspinlock_stat.h

+62 −101

Original line number	Diff line number	Diff line
		@@ -38,8 +38,8 @@
		* Subtracting lock_use_node[234] from lock_slowpath will give you
		* lock_use_node1.
		*
		* Writing to the "reset_counters" file will reset all the above counter
		* values.
		* 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
		@@ -48,27 +48,7 @@
		*
		* There may be slight difference between pv_kick_wake and pv_kick_unlock.
		*/
		enum qlock_stats {
		qstat_pv_hash_hops,
		qstat_pv_kick_unlock,
		qstat_pv_kick_wake,
		qstat_pv_latency_kick,
		qstat_pv_latency_wake,
		qstat_pv_lock_stealing,
		qstat_pv_spurious_wakeup,
		qstat_pv_wait_again,
		qstat_pv_wait_early,
		qstat_pv_wait_head,
		qstat_pv_wait_node,
		qstat_lock_pending,
		qstat_lock_slowpath,
		qstat_lock_use_node2,
		qstat_lock_use_node3,
		qstat_lock_use_node4,
		qstat_lock_no_node,
		qstat_num, /* Total number of statistical counters */
		qstat_reset_cnts = qstat_num,
		};
		#include "lock_events.h"

		#ifdef CONFIG_QUEUED_LOCK_STAT
		/*
		@@ -79,99 +59,91 @@ enum qlock_stats {
		#include <linux/sched/clock.h>
		#include <linux/fs.h>

		static const char * const qstat_names[qstat_num + 1] = {
		[qstat_pv_hash_hops] = "pv_hash_hops",
		[qstat_pv_kick_unlock] = "pv_kick_unlock",
		[qstat_pv_kick_wake] = "pv_kick_wake",
		[qstat_pv_spurious_wakeup] = "pv_spurious_wakeup",
		[qstat_pv_latency_kick] = "pv_latency_kick",
		[qstat_pv_latency_wake] = "pv_latency_wake",
		[qstat_pv_lock_stealing] = "pv_lock_stealing",
		[qstat_pv_wait_again] = "pv_wait_again",
		[qstat_pv_wait_early] = "pv_wait_early",
		[qstat_pv_wait_head] = "pv_wait_head",
		[qstat_pv_wait_node] = "pv_wait_node",
		[qstat_lock_pending] = "lock_pending",
		[qstat_lock_slowpath] = "lock_slowpath",
		[qstat_lock_use_node2] = "lock_use_node2",
		[qstat_lock_use_node3] = "lock_use_node3",
		[qstat_lock_use_node4] = "lock_use_node4",
		[qstat_lock_no_node] = "lock_no_node",
		[qstat_reset_cnts] = "reset_counters",
		#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
		*/
		static DEFINE_PER_CPU(unsigned long, qstats[qstat_num]);
		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
		*
		* The following counters are handled specially:
		* 1. qstat_pv_latency_kick
		* 1. pv_latency_kick
		* Average kick latency (ns) = pv_latency_kick/pv_kick_unlock
		* 2. qstat_pv_latency_wake
		* 2. pv_latency_wake
		* Average wake latency (ns) = pv_latency_wake/pv_kick_wake
		* 3. qstat_pv_hash_hops
		* 3. pv_hash_hops
		* Average hops/hash = pv_hash_hops/pv_kick_unlock
		*/
		static ssize_t qstat_read(struct file file, char __user user_buf,
		static ssize_t lockevent_read(struct file file, char __user user_buf,
		size_t count, loff_t *ppos)
		{
		char buf[64];
		int cpu, counter, len;
		u64 stat = 0, kicks = 0;
		int cpu, id, len;
		u64 sum = 0, kicks = 0;

		/*
		* Get the counter ID stored in file->f_inode->i_private
		*/
		counter = (long)file_inode(file)->i_private;
		id = (long)file_inode(file)->i_private;

		if (counter >= qstat_num)
		if (id >= lockevent_num)
		return -EBADF;

		for_each_possible_cpu(cpu) {
		stat += per_cpu(qstats[counter], cpu);
		sum += per_cpu(lockevents[id], cpu);
		/*
		* Need to sum additional counter for some of them
		* Need to sum additional counters for some of them
		*/
		switch (counter) {
		switch (id) {

		case qstat_pv_latency_kick:
		case qstat_pv_hash_hops:
		kicks += per_cpu(qstats[qstat_pv_kick_unlock], cpu);
		case LOCKEVENT_pv_latency_kick:
		case LOCKEVENT_pv_hash_hops:
		kicks += per_cpu(EVENT_COUNT(pv_kick_unlock), cpu);
		break;

		case qstat_pv_latency_wake:
		kicks += per_cpu(qstats[qstat_pv_kick_wake], cpu);
		case LOCKEVENT_pv_latency_wake:
		kicks += per_cpu(EVENT_COUNT(pv_kick_wake), cpu);
		break;
		}
		}

		if (counter == qstat_pv_hash_hops) {
		if (id == LOCKEVENT_pv_hash_hops) {
		u64 frac = 0;

		if (kicks) {
		frac = 100ULL * do_div(stat, 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", stat, frac);
		len = snprintf(buf, sizeof(buf) - 1, "%llu.%02llu\n",
		sum, frac);
		} else {
		/*
		* Round to the nearest ns
		*/
		if ((counter == qstat_pv_latency_kick) \|\|
		(counter == qstat_pv_latency_wake)) {
		if ((id == LOCKEVENT_pv_latency_kick) \|\|
		(id == LOCKEVENT_pv_latency_wake)) {
		if (kicks)
		stat = DIV_ROUND_CLOSEST_ULL(stat, kicks);
		sum = DIV_ROUND_CLOSEST_ULL(sum, kicks);
		}
		len = snprintf(buf, sizeof(buf) - 1, "%llu\n", stat);
		len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
		}

		return simple_read_from_buffer(user_buf, count, ppos, buf, len);
		@@ -180,11 +152,9 @@ static ssize_t qstat_read(struct file file, char __user user_buf,
		/*
		* Function to handle write request
		*
		* When counter = reset_cnts, reset all the counter values.
		* Since the counter updates aren't atomic, the resetting is done twice
		* to make sure that the counters are very likely to be all cleared.
		* When id = .reset_cnts, reset all the counter values.
		*/
		static ssize_t qstat_write(struct file file, const char __user user_buf,
		static ssize_t lockevent_write(struct file file, const char __user user_buf,
		size_t count, loff_t *ppos)
		{
		int cpu;
		@@ -192,14 +162,14 @@ static ssize_t qstat_write(struct file file, const char __user user_buf,
		/*
		* Get the counter ID stored in file->f_inode->i_private
		*/
		if ((long)file_inode(file)->i_private != qstat_reset_cnts)
		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(qstats, cpu);
		unsigned long *ptr = per_cpu_ptr(lockevents, cpu);

		for (i = 0 ; i < qstat_num; i++)
		for (i = 0 ; i < lockevent_num; i++)
		WRITE_ONCE(ptr[i], 0);
		}
		return count;
		@@ -208,9 +178,9 @@ static ssize_t qstat_write(struct file file, const char __user user_buf,
		/*
		* Debugfs data structures
		*/
		static const struct file_operations fops_qstat = {
		.read = qstat_read,
		.write = qstat_write,
		static const struct file_operations fops_lockevent = {
		.read = lockevent_read,
		.write = lockevent_write,
		.llseek = default_llseek,
		};

		@@ -219,10 +189,10 @@ static const struct file_operations fops_qstat = {
		*/
		static int __init init_qspinlock_stat(void)
		{
		struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL);
		struct dentry *d_counts = debugfs_create_dir("qlockstat", NULL);
		int i;

		if (!d_qstat)
		if (!d_counts)
		goto out;

		/*
		@@ -232,39 +202,31 @@ static int __init init_qspinlock_stat(void)
		* root is allowed to do the read/write to limit impact to system
		* performance.
		*/
		for (i = 0; i < qstat_num; i++)
		if (!debugfs_create_file(qstat_names[i], 0400, d_qstat,
		(void *)(long)i, &fops_qstat))
		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(qstat_names[qstat_reset_cnts], 0200, d_qstat,
		(void *)(long)qstat_reset_cnts, &fops_qstat))
		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_qstat);
		debugfs_remove_recursive(d_counts);
		out:
		pr_warn("Could not create 'qlockstat' debugfs entries\n");
		return -ENOMEM;
		}
		fs_initcall(init_qspinlock_stat);

		/*
		* Increment the PV qspinlock statistical counters
		*/
		static inline void qstat_inc(enum qlock_stats stat, bool cond)
		{
		if (cond)
		this_cpu_inc(qstats[stat]);
		}

		/*
		* PV hash hop count
		*/
		static inline void qstat_hop(int hopcnt)
		static inline void lockevent_pv_hop(int hopcnt)
		{
		this_cpu_add(qstats[qstat_pv_hash_hops], hopcnt);
		this_cpu_add(EVENT_COUNT(pv_hash_hops), hopcnt);
		}

		/*
		@@ -276,7 +238,7 @@ static inline void __pv_kick(int cpu)

		per_cpu(pv_kick_time, cpu) = start;
		pv_kick(cpu);
		this_cpu_add(qstats[qstat_pv_latency_kick], sched_clock() - start);
		this_cpu_add(EVENT_COUNT(pv_latency_kick), sched_clock() - start);
		}

		/*
		@@ -289,9 +251,9 @@ static inline void __pv_wait(u8 *ptr, u8 val)
		*pkick_time = 0;
		pv_wait(ptr, val);
		if (*pkick_time) {
		this_cpu_add(qstats[qstat_pv_latency_wake],
		this_cpu_add(EVENT_COUNT(pv_latency_wake),
		sched_clock() - *pkick_time);
		qstat_inc(qstat_pv_kick_wake, true);
		lockevent_inc(pv_kick_wake);
		}
		}

		@@ -300,7 +262,6 @@ static inline void __pv_wait(u8 *ptr, u8 val)

		#else /* CONFIG_QUEUED_LOCK_STAT */

		static inline void qstat_inc(enum qlock_stats stat, bool cond) { }
		static inline void qstat_hop(int hopcnt) { }
		static inline void lockevent_pv_hop(int hopcnt) { }

		#endif /* CONFIG_QUEUED_LOCK_STAT */