From c46261de0d98372112d8edf16f74ce418a268d46 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 19 Jul 2007 01:48:57 -0700 Subject: lockstat: human readability tweaks Present all this fancy new lock statistics information: *warning, _wide_ output ahead* (output edited for purpose of brevity) # cat /proc/lock_stat lock_stat version 0.1 ----------------------------------------------------------------------------------------------------------------------------------------------------------------- class name contentions waittime-min waittime-max waittime-total acquisitions holdtime-min holdtime-max holdtime-total ----------------------------------------------------------------------------------------------------------------------------------------------------------------- &inode->i_mutex: 14458 6.57 398832.75 2469412.23 6768876 0.34 11398383.65 339410830.89 --------------- &inode->i_mutex 4486 [] pipe_wait+0x86/0x8d &inode->i_mutex 0 [] pipe_write_fasync+0x29/0x5d &inode->i_mutex 0 [] pipe_read+0x74/0x3a5 &inode->i_mutex 0 [] do_lookup+0x81/0x1ae ................................................................................................................................................................. &inode->i_data.tree_lock-W: 491 0.27 62.47 493.89 2477833 0.39 468.89 1146584.25 &inode->i_data.tree_lock-R: 65 0.44 4.27 48.78 26288792 0.36 184.62 10197458.24 -------------------------- &inode->i_data.tree_lock 46 [] __do_page_cache_readahead+0x69/0x24f &inode->i_data.tree_lock 31 [] add_to_page_cache+0x31/0xba &inode->i_data.tree_lock 0 [] __do_page_cache_readahead+0xc2/0x24f &inode->i_data.tree_lock 0 [] find_get_page+0x1a/0x58 ................................................................................................................................................................. proc_inum_idr.lock: 0 0.00 0.00 0.00 36 0.00 65.60 148.26 proc_subdir_lock: 0 0.00 0.00 0.00 3049859 0.00 106.81 1563212.42 shrinker_rwsem-W: 0 0.00 0.00 0.00 5 0.00 1.73 3.68 shrinker_rwsem-R: 0 0.00 0.00 0.00 633 2.57 246.57 10909.76 'contentions' and 'acquisitions' are the number of such events measured (since the last reset). The waittime- and holdtime- (min, max, total) numbers are presented in microseconds. If there are any contention points, the lock class is presented in the block format (as i_mutex and tree_lock above), otherwise a single line of output is presented. The output is sorted on absolute number of contentions (read + write), this should get the worst offenders presented first, so that: # grep : /proc/lock_stat | head will quickly show who's bad. The stats can be reset using: # echo 0 > /proc/lock_stat [bunk@stusta.de: make 2 functions static] [akpm@linux-foundation.org: fix printk warning] Signed-off-by: Peter Zijlstra Acked-by: Ingo Molnar Acked-by: Jason Baron Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/lockdep.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'kernel/lockdep.c') diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 70ca4db28af..a8dc99d9fef 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -149,6 +149,50 @@ static void lock_time_inc(struct lock_time *lt, s64 time) lt->nr++; } +static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) +{ + dst->min += src->min; + dst->max += src->max; + dst->total += src->total; + dst->nr += src->nr; +} + +struct lock_class_stats lock_stats(struct lock_class *class) +{ + struct lock_class_stats stats; + int cpu, i; + + memset(&stats, 0, sizeof(struct lock_class_stats)); + for_each_possible_cpu(cpu) { + struct lock_class_stats *pcs = + &per_cpu(lock_stats, cpu)[class - lock_classes]; + + for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) + stats.contention_point[i] += pcs->contention_point[i]; + + lock_time_add(&pcs->read_waittime, &stats.read_waittime); + lock_time_add(&pcs->write_waittime, &stats.write_waittime); + + lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); + lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); + } + + return stats; +} + +void clear_lock_stats(struct lock_class *class) +{ + int cpu; + + for_each_possible_cpu(cpu) { + struct lock_class_stats *cpu_stats = + &per_cpu(lock_stats, cpu)[class - lock_classes]; + + memset(cpu_stats, 0, sizeof(struct lock_class_stats)); + } + memset(class->contention_point, 0, sizeof(class->contention_point)); +} + static struct lock_class_stats *get_lock_stats(struct lock_class *class) { return &get_cpu_var(lock_stats)[class - lock_classes]; -- cgit v1.2.3-70-g09d2