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Commit c7e78cff authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

lockstat: contend with points 



We currently only provide points that have to wait on contention, also
lists the points we have to wait for.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7317d7b8

Documentation/lockstat.txt

+32 −18
Original line number Diff line number Diff line
@@ -71,34 +71,48 @@ Look at the current lock statistics: 


# less /proc/lock_stat



01 lock_stat version 0.2

01 lock_stat version 0.3

02 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

03                               class name    con-bounces    contentions   waittime-min   waittime-max waittime-total    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total

04 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

05

06               &inode->i_data.tree_lock-W:            15          21657           0.18     1093295.30 11547131054.85             58          10415           0.16          87.51        6387.60

07               &inode->i_data.tree_lock-R:             0              0           0.00           0.00           0.00          23302         231198           0.25           8.45       98023.38

08               --------------------------

09                 &inode->i_data.tree_lock              0          [<ffffffff8027c08f>] add_to_page_cache+0x5f/0x190

10

11 ...............................................................................................................................................................................................

12

13                              dcache_lock:          1037           1161           0.38          45.32         774.51           6611         243371           0.15         306.48       77387.24

14                              -----------

15                              dcache_lock            180          [<ffffffff802c0d7e>] sys_getcwd+0x11e/0x230

16                              dcache_lock            165          [<ffffffff802c002a>] d_alloc+0x15a/0x210

17                              dcache_lock             33          [<ffffffff8035818d>] _atomic_dec_and_lock+0x4d/0x70

18                              dcache_lock              1          [<ffffffff802beef8>] shrink_dcache_parent+0x18/0x130

06                          &mm->mmap_sem-W:           233            538 18446744073708       22924.27      607243.51           1342          45806           1.71        8595.89     1180582.34

07                          &mm->mmap_sem-R:           205            587 18446744073708       28403.36      731975.00           1940         412426           0.58      187825.45     6307502.88

08                          ---------------

09                            &mm->mmap_sem            487          [<ffffffff8053491f>] do_page_fault+0x466/0x928

10                            &mm->mmap_sem            179          [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d

11                            &mm->mmap_sem            279          [<ffffffff80210a57>] sys_mmap+0x75/0xce

12                            &mm->mmap_sem             76          [<ffffffff802a490b>] sys_munmap+0x32/0x59

13                          ---------------

14                            &mm->mmap_sem            270          [<ffffffff80210a57>] sys_mmap+0x75/0xce

15                            &mm->mmap_sem            431          [<ffffffff8053491f>] do_page_fault+0x466/0x928

16                            &mm->mmap_sem            138          [<ffffffff802a490b>] sys_munmap+0x32/0x59

17                            &mm->mmap_sem            145          [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d

18

19 ...............................................................................................................................................................................................

20

21                              dcache_lock:           621            623           0.52         118.26        1053.02           6745          91930           0.29         316.29      118423.41

22                              -----------

23                              dcache_lock            179          [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54

24                              dcache_lock            113          [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb

25                              dcache_lock             99          [<ffffffff802ca0dc>] d_rehash+0x1b/0x44

26                              dcache_lock            104          [<ffffffff802cbca0>] d_instantiate+0x36/0x8a

27                              -----------

28                              dcache_lock            192          [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54

29                              dcache_lock             98          [<ffffffff802ca0dc>] d_rehash+0x1b/0x44

30                              dcache_lock             72          [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb

31                              dcache_lock            112          [<ffffffff802cbca0>] d_instantiate+0x36/0x8a



This excerpt shows the first two lock class statistics. Line 01 shows the

output version - each time the format changes this will be updated. Line 02-04

show the header with column descriptions. Lines 05-10 and 13-18 show the actual

show the header with column descriptions. Lines 05-18 and 20-31 show the actual

statistics. These statistics come in two parts; the actual stats separated by a

short separator (line 08, 14) from the contention points.

short separator (line 08, 13) from the contention points.



The first lock (05-10) is a read/write lock, and shows two lines above the

The first lock (05-18) is a read/write lock, and shows two lines above the

short separator. The contention points don't match the column descriptors,

they have two: contentions and [<IP>] symbol.

they have two: contentions and [<IP>] symbol. The second set of contention

points are the points we're contending with.



The integer part of the time values is in us.

include/linux/lockdep.h

+9 −4
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ struct lock_class_key { 
	struct lockdep_subclass_key	subkeys[MAX_LOCKDEP_SUBCLASSES];

};



#define LOCKSTAT_POINTS		4



/*

 * The lock-class itself:

 */
@@ -119,7 +121,8 @@ struct lock_class { 
	int				name_version;



#ifdef CONFIG_LOCK_STAT

	unsigned long			contention_point[4];

	unsigned long			contention_point[LOCKSTAT_POINTS];

	unsigned long			contending_point[LOCKSTAT_POINTS];

#endif

};
@@ -144,6 +147,7 @@ enum bounce_type { 


struct lock_class_stats {

	unsigned long			contention_point[4];

	unsigned long			contending_point[4];

	struct lock_time		read_waittime;

	struct lock_time		write_waittime;

	struct lock_time		read_holdtime;
@@ -165,6 +169,7 @@ struct lockdep_map { 
	const char			*name;

#ifdef CONFIG_LOCK_STAT

	int				cpu;

	unsigned long			ip;

#endif

};
@@ -355,7 +360,7 @@ struct lock_class_key { }; 
#ifdef CONFIG_LOCK_STAT



extern void lock_contended(struct lockdep_map *lock, unsigned long ip);

extern void lock_acquired(struct lockdep_map *lock);

extern void lock_acquired(struct lockdep_map *lock, unsigned long ip);



#define LOCK_CONTENDED(_lock, try, lock)			\

do {								\
@@ -363,13 +368,13 @@ do { \ 
		lock_contended(&(_lock)->dep_map, _RET_IP_);	\

		lock(_lock);					\

	}							\

	lock_acquired(&(_lock)->dep_map);			\

	lock_acquired(&(_lock)->dep_map, _RET_IP_);			\

} while (0)



#else /* CONFIG_LOCK_STAT */



#define lock_contended(lockdep_map, ip) do {} while (0)

#define lock_acquired(lockdep_map) do {} while (0)

#define lock_acquired(lockdep_map, ip) do {} while (0)



#define LOCK_CONTENDED(_lock, try, lock) \

	lock(_lock)

kernel/lockdep.c

+21 −12
Original line number Diff line number Diff line
@@ -136,16 +136,16 @@ static inline struct lock_class *hlock_class(struct held_lock *hlock) 
#ifdef CONFIG_LOCK_STAT

static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], lock_stats);



static int lock_contention_point(struct lock_class *class, unsigned long ip)

static int lock_point(unsigned long points[], unsigned long ip)

{

	int i;



	for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {

		if (class->contention_point[i] == 0) {

			class->contention_point[i] = ip;

	for (i = 0; i < LOCKSTAT_POINTS; i++) {

		if (points[i] == 0) {

			points[i] = ip;

			break;

		}

		if (class->contention_point[i] == ip)

		if (points[i] == ip)

			break;

	}
@@ -185,6 +185,9 @@ struct lock_class_stats lock_stats(struct lock_class *class) 
		for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)

			stats.contention_point[i] += pcs->contention_point[i];



		for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)

			stats.contending_point[i] += pcs->contending_point[i];



		lock_time_add(&pcs->read_waittime, &stats.read_waittime);

		lock_time_add(&pcs->write_waittime, &stats.write_waittime);
@@ -209,6 +212,7 @@ void clear_lock_stats(struct lock_class *class) 
		memset(cpu_stats, 0, sizeof(struct lock_class_stats));

	}

	memset(class->contention_point, 0, sizeof(class->contention_point));

	memset(class->contending_point, 0, sizeof(class->contending_point));

}



static struct lock_class_stats *get_lock_stats(struct lock_class *class)
@@ -3001,7 +3005,7 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip) 
	struct held_lock *hlock, *prev_hlock;

	struct lock_class_stats *stats;

	unsigned int depth;

	int i, point;

	int i, contention_point, contending_point;



	depth = curr->lockdep_depth;

	if (DEBUG_LOCKS_WARN_ON(!depth))
@@ -3025,18 +3029,22 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip) 
found_it:

	hlock->waittime_stamp = sched_clock();



	point = lock_contention_point(hlock_class(hlock), ip);

	contention_point = lock_point(hlock_class(hlock)->contention_point, ip);

	contending_point = lock_point(hlock_class(hlock)->contending_point,

				      lock->ip);



	stats = get_lock_stats(hlock_class(hlock));

	if (point < ARRAY_SIZE(stats->contention_point))

		stats->contention_point[point]++;

	if (contention_point < LOCKSTAT_POINTS)

		stats->contention_point[contention_point]++;

	if (contending_point < LOCKSTAT_POINTS)

		stats->contending_point[contending_point]++;

	if (lock->cpu != smp_processor_id())

		stats->bounces[bounce_contended + !!hlock->read]++;

	put_lock_stats(stats);

}



static void

__lock_acquired(struct lockdep_map *lock)

__lock_acquired(struct lockdep_map *lock, unsigned long ip)

{

	struct task_struct *curr = current;

	struct held_lock *hlock, *prev_hlock;
@@ -3085,6 +3093,7 @@ found_it: 
	put_lock_stats(stats);



	lock->cpu = cpu;

	lock->ip = ip;

}



void lock_contended(struct lockdep_map *lock, unsigned long ip)
@@ -3106,7 +3115,7 @@ void lock_contended(struct lockdep_map *lock, unsigned long ip) 
}

EXPORT_SYMBOL_GPL(lock_contended);



void lock_acquired(struct lockdep_map *lock)

void lock_acquired(struct lockdep_map *lock, unsigned long ip)

{

	unsigned long flags;
@@ -3119,7 +3128,7 @@ void lock_acquired(struct lockdep_map *lock) 
	raw_local_irq_save(flags);

	check_flags(flags);

	current->lockdep_recursion = 1;

	__lock_acquired(lock);

	__lock_acquired(lock, ip);

	current->lockdep_recursion = 0;

	raw_local_irq_restore(flags);

}

kernel/lockdep_proc.c

+19 −2
Original line number Diff line number Diff line
@@ -557,7 +557,7 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 
	if (stats->read_holdtime.nr)

		namelen += 2;



	for (i = 0; i < ARRAY_SIZE(class->contention_point); i++) {

	for (i = 0; i < LOCKSTAT_POINTS; i++) {

		char sym[KSYM_SYMBOL_LEN];

		char ip[32];
@@ -574,6 +574,23 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 
				stats->contention_point[i],

				ip, sym);

	}

	for (i = 0; i < LOCKSTAT_POINTS; i++) {

		char sym[KSYM_SYMBOL_LEN];

		char ip[32];



		if (class->contending_point[i] == 0)

			break;



		if (!i)

			seq_line(m, '-', 40-namelen, namelen);



		sprint_symbol(sym, class->contending_point[i]);

		snprintf(ip, sizeof(ip), "[<%p>]",

				(void *)class->contending_point[i]);

		seq_printf(m, "%40s %14lu %29s %s\n", name,

				stats->contending_point[i],

				ip, sym);

	}

	if (i) {

		seq_puts(m, "\n");

		seq_line(m, '.', 0, 40 + 1 + 10 * (14 + 1));
@@ -583,7 +600,7 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data) 


static void seq_header(struct seq_file *m)

{

	seq_printf(m, "lock_stat version 0.2\n");

	seq_printf(m, "lock_stat version 0.3\n");

	seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));

	seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "

			"%14s %14s\n",

kernel/mutex.c

+1 −1
Original line number Diff line number Diff line
@@ -184,7 +184,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, 
	}



done:

	lock_acquired(&lock->dep_map);

	lock_acquired(&lock->dep_map, ip);

	/* got the lock - rejoice! */

	mutex_remove_waiter(lock, &waiter, task_thread_info(task));

	debug_mutex_set_owner(lock, task_thread_info(task));