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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

5 files changed, 82 insertions, 37 deletions

diff --git a/Documentation/lockstat.txt b/Documentation/lockstat.txt
index 02f36f5c64fe..9cb9138f7a79 100644
--- a/Documentation/lockstat.txt
+++ b/Documentation/lockstat.txt
@@ -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.
 
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 0aa657aa8a1e..fc9f8e88123b 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -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)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index dbda475b13bd..234a9dccb4be 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -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);
 }
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 8d3a6eba8d5a..13716b813896 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -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",
diff --git a/kernel/mutex.c b/kernel/mutex.c
index 12c779dc65d4..39a3816b68d9 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -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));